I have "center drilled" houses to run home runs to the panel before. Starting with a 3/4" hole at the far end of the house and increasing it to 1 1/4' and 2' as I got closer to the panel. The inspector was quite impressed with my work and complemented me on how neat and clean my work was.
Dang Dustin, you nailed it again. Man I love this show and your truly a mentor of mine. I have been a general contractor for 30+ years and I still find a ton of value in your teachings.
Like he said, it depends on your local inspector. With 4 conductors in a 1" hole, my inspector said I could only have 2. --- Drilled a new 3/4" hole and re-ran the conductors. All about getting signed off. ---
Bundling has absolutely zero negative effect on wires/cables. I have examined thousands of cables that spent their lives being bundled and stuffed through holes. The number of failures or installed of damed were....zero. I spent decades replacing services in AZ. By the time I retired I had done several thousand. Every service is outdoors here and all the cables enter though a hole in the back. It has been done that way way before my time and continues to this day. Why? Because it is a simple and safe installation.
One commentor here mentioned the possibility of INDUCTANCE coupling. If a supposedly dead conductor is not bonded or grounded properly, enough voltage can be induced into it that it can become a problem. (Commentor said he saw someone get electrocuted, although it was in the thousands of volts.)
Hey Swedish electrician here, damn you guys have a easy job. Here in Sweden you have to draw all wires in plastic pipes (when the installation are in walls). But that can also be very useful when you need to change wires/cabels.
@@davidsherrill375 those rules have nothing to do with the covering of the conductors in metal - it’s a partnership with the pipe fitters union to have metal conduit and metal pipes. Numerous “union” cities were like that. Electrical was and in some cases still is “conduit only” with flex only allowed in limited length or conditions.
I would argue that wall insulation has more effect on the temperature of the conductors than bundling does. Wires in open cavity walls can dissipate heat far easier than having a bat of fiberglass insulation or spray-in insulation around them.
Well that would fall under the ambient temperature adjustments that you should be considering. If you are an electrician, then you should be factoring it with insulation ratings.
310.15(B)(3)(a) provides a clear definition of multiple cables in a “bundle”. As a general rule, I stick to 3 which derates the conductors by 80%. This allows for other adjustments that might be applied in addition to bundling such as ambient temperature. Thanks for the video.
Agree... I too stick to two cables per 3/4" hole. Occasionally, I have to run three through and just up the hole size to 1". Just makes pulling the cable easier.
@@ericthered9655 that much man I really haven't used it much but I picked up a used Milwaukee hole hawg the smaller on with just 1 speed but it works great but I got it used off eBay for like $120 or something I don't remember but it wasn't near $500
I had an inspector tell me the limit on the amount of romex in the hole was "There wasn't enough room for thermal expansion". I had to stifle a laugh. In his mind I think he expects copper to expand by orders of magnitude when it gets hot.
Not relevant to this electric issue, but when I learned blacksmithing, I was shocked to learn how important thermal expansion was to the work. I assumed it could be ignored because it would be so small, but not so when dealing with the high temps of smithing. When you heat up steel to a typical (yellow hot) forging temp of around 2000 F, a 1 ft length of steel will expand in length about 1/8". So when we are punching holes in hot metal, the expansion becomes very important to compensate for. If you need two holes 12" apart when cold if we measure when hot we will be 1/8" off. So often we mark the metal when cold to deal with this. Because of the very high temps, the expansion becomes significant and important to understand and workaround. Of course, with loose wires, they never got hot enough for the expansion to create any effect we need to deal with, at least not in residential wiring. It's all about how heat gets trapped and causes temps to rise more. forcing us to derate the current capacity of the wires,
@@CurtWelch you're right, not relevant, but cool nonetheless. I never thought about how much metal expands and contracts on that scale, I'm usually reminded of it when mile long sections of rail kink in the hot sun because they've expanded so much.
2:42 I have seen an electrician get killed from that issue, it was actually inductive coupling. The new wire run wasn't grounded running next to a live 7.2KV 3 phase run, which induced enough voltage and current into the new "dead" cable. He grabbed the cable to work on it, not verifying that there was a ground in place, and was electrocuted. That was preventable for sure. 😢
Yeah, I think the major issue is inductive coupling, not capacitive. In AC inductive coupling can look an awful lot like capacitive coupling until you realize that the capacitive plate sized of two conductors running in parallel is so tiny that really only noise will transfer. Inductive coupling can transfer significant power. Two conductors run in parallel is a simple transformer with a single winding on both the primary and secondary.
well, yeah. you shouldn't run anything close to a High Voltage cable. there used to be a thing- you could run conductors from different voltage systems in the same raceway, as long as everything was rated for the highest voltage present.
@@larrystuder8543 It's still allowed if the voltages are identified as different, but I don't have the code reference. Usually, it's not a problem since most wire we use is rated for 600 volts. This much higher voltage is naturally more dangerous. I'm not sure what precaution is effective, but it doesn't hurt to ALWAYS test with a non-contact voltage tester.
I think some of the limitations are because we used to run 14/2-3 (or even smaller) through walls, while today it’s more common to see 12/2-3 run through walls for additional safety and capacity when needed. The margin of safety between 14 and 12 awg wires is significant, and running 12 awg limits the heat, capacitive resistance, inductive resistance, and expansion those wires might otherwise experience with smaller wires. Running 12 awg is like future-proofing the home. I always recommend running 12 awg, as well as running CAT-6 to every room in the house (and 2-4 runs to every possible media location). CAT-6 is useful in so many ways that it just makes sense to run it before the drywall goes up.
While we're on the subject of romex running, can you make a video on techniques to rolling out home runs? I've done it now twice, and it just seems like I'm missing some very simple tricks because it takes me FOREVER. Also, what staples do you use and how do you install them? The ones I've tried are a nuisance to put in, and I always end up smashing my thumb multiple times. Would love a video on BASIC techniques of pulling romex, drilling holes; hammering staples and boxes. Just can't seem to find a groove you know
The best way to hammer the staple in without smashing your thumb is by using the Mr Miagi technique. Gently tap with hammer to start staple. Breathe in, breathe out, swing once, thumb no get squish like grape!
do you mean actually uncoiling the wire? you need some kind of spooling device. for the absolute simplest, make a platform out of some kind of scrap material. make a cone in the middle that the coil of romex will fit over, and hang it from the ceiling joist or truss with some kind of swivel so it turns freely. or if you are going to be doing a lot, there are dozens of spooling devices you can buy.
Well in Canada, our equivalent of roomex comes on reels already, which I am guessing is not always the case in the US. This means any sturdy rod, pipe or whatever is all one needs. That and a stand for the pipe to rest on.
Capacitance is not an issue for 60Hz wires. As stated by another commenter, the capacitance between the hot and ground conductors in a Romex cable is greater than the capacitive coupling between arbitrary pairs of Romex cable. The reason for limiting conductors in shared holes in the rules must be some of the other things you mentioned besides the capacitance. If we assume that Romex has about 20pF per foot, 100' gives about 2000pF, which has a capacitive impedance of about 1 Meg Ohms at 60Hz. That would give about 100 micro-Amps of current flow. If we consider another Romex cable as close as it could be for that same 100' length, the capacitance would probably be ten times less. The result would be insignificant.
The capacitance is not in series with the conductor, so it does not impede the current flow in any way. The capacitance is BETWEEN conductors and results in tiny amount of ADDITIONAL current (leakage current). The conductor derating table is there for heat dissipation reasons due to the cables being bundled. Notice that the derating table references ambient temperature, which is a huge hint that they are concerned about temperature rise in the cable.
@@njnear Yes, and the total capacitance is related to total length, so even though there would be a larger capacitance in an exceptionally long run, the capacitance per unit length is only about 20pF (virtually no effect). The resistive losses are also related to unit length, so the heat produced (per unit length) is the key factor. Any time the conductors (and heat) are concentrated into a small area with restricted thermal paths, the temperature rise concern is valid. It is more important for multiple cables in longer enclosed paths because a 2" long hole in a stud may generate more local heat, but the copper conductors will help conduct this heat away from the tight area, spreading the heat out over several more inches, lowering the peak temperature of the conductors (and more importantly, the insulators) in the hole.
Capacitance or inductance is very possible in a 60 hz application. It’s depends on the voltage levels. At normal residential voltage level (ie: 220/120) I will agree it’s not an issue. But, In industrial applications where you have full line voltage (kV) to a switch gear it is a concern that must be keep in mind.
@@sparky_oo1955 Yes, for the power companies with hundreds of miles of transmission lines, they need to be concerned about inductance and capacitance in their designs and controls, but for residential or commercial applications (normal people), the effects at 60Hz can be ignored. Also, the inductance and capacitance don't depend on voltage, but the currents that flow are always Voltage/Impedance.
After a solid year of trying to find an answer to this question. Thank you. You sir, are a saint. Thank you for taking the time to explain in detail the why’s of everything electrical. I can’t count the many times this has informed or helped me on my daily job as a solar electrician.. coming from residential they’re were a lot of commercial-grade codes or utility code I was unaware of. I appreciate you since this is the best way I go about not forgetting. it’s just my learning style. It’s gotta be showed and explained to me, can’t always just read from a book 🤣
Your "heat not an issue" argument works fine in typical inside walls, but it's worth considering in outside walls that are insulated. Many years ago, when I was in college, I worked at the local electric utility, and one of the things they asked me to do was to test various types of insulation and their effects on wires. We built a 4-segment wall, ran several conductors through it (14-2 WG Romex, 12-2 Romex, 12 AWG in conduit, 14 AWG in conduit, 14 AWG post and knob) through it, insulated the various sections with different insulating materials (none, fiberglass, cellulose, foam), installed thermocouples to measure the temperatures, and then ran each circuit at various increasing current levels. When we got to 20 amps on the 14-2 Romex circuit (yes, that exceeds NEC but can be a common mistake if 14-2 is connected to a 20A circuit breaker; the utility was aware that some service/panel upgrades used 20A breakers connected to 12 AWG wire at the panel that then connected to existing 14 AWG wire elsewhere in the house), the wall started smoking and caught fire after just 5 minutes of continuous load. The fire started in the foam section, then spread to the cellulose. Needless to say, the test was quickly terminated. The test results were shared with several organizations, and led to some of the electrical and building and insulation code changes we see today.
You make a good point, it's not all about heat. I assumed inductive effects were more prominent, but as you say there is a parallel capacitive effect as well. I'm guessing this could play havoc with the charge on ground wires, and maybe even cause nuisance tripping of AFCI's.
I doubt AFCIs would trip, they're looking for the high frequency characteristics of arcing, and need to ignore the line frequency as it is omnipresent. The more capacitance you have, the lower the resonant frequency will be..
I have a common practice of drilling a 3/4 hole, and if another run is needed, drill another hole. You can fit comfortably 3 runs of 12/2 and 14/3, and 4 runs of 14/2. My biggest concern of overcrowding is not the breathing factor, but drywall screws skewering the run! Though nail plates are used for some reason, a lot of people think longer screws are better to hang drywall, or put up siding.....in my own home, I replaced a junky GE Slimline panel with a nice Square D. The original panel had no main cutoff, though it was installed in 1981, and passed inspe tion (?), and when I purposely forced tripped a Slimline breaker the damn breaker did not trip...so I could have just replaced all the breakers, but with that expense, decided a new panel was needed. Anyway, there was a siding nail stuck inside the service conductor leading to the panel from the meter. I replaced that wire bundle, opened the cover and saw the neutral was indeed poked. Yes, could have energized my whole house exterior....anyway, catch your " act" on the next video!
@@AndrewBrowner The holes are not straight. Switching directions averages the angles out so the wire has less friction. Try it. The difference is obvious.
I would raise two points. First, capacitive leakage causes some heating. Second, you should wiring not for average use, but for the worst case, because it only takes once for the house to burn down.
Couple years ago, I ran a wood screw into a stud for a shelf bracket…pop went breaker Opened the wall to find the screw went directly thru the hole, thru the Romex…. No slack to fix it with a wire nut, so I used a crimp butt connector, after crimping I soldered the connector to be safe and covered with heat shrink.
Omg it's such an breath of fresh air bro to see someone not try and overcompljcate these codes and try and act like they're some sort of electrical guru : /
an independent lab ran testing on how many wires can be jammed in a hole without overheating them, so they put various numbers of cables in a hole, foamed the hole, like insulators now always do, and their determination was that you pretty much couldn't exceed 3 cables before you started overheating wires. and capacitance between wires? not a thing I've ever heard of. induced voltage, yes. never capacitance. and if capacitance is the issue in the wire bundling charts, why is ambient temperature a factor?
You are right, capacitance would be so low with 60 cycle, 240v lines as to be difficult to measure. Even inductance would cancel out as cables tend to twist over distance.
Fwiw, I always carry 3/4 and 1 inch bits. If I know I need to put anything more than a 12/3 and 12/2 in a hole (6/3 alone or 10-3 with 12/2 etc) I always just use the 1 incher. Makes the pulls so much faster, I feel like it saves my customers money. Same logic for anticipating 2 romex per hole. I only do 3+ if there's weird framing that only gives me a single path, but again in those spots I use a 1 inch and ream it if it needs it.
AFAIK, the heat thing is about insulated walls. With the 2020 NEC requiring GFCIs for almost everything, you may want to limit bundling so coupling between cables doesn't cause nuisance trips.
I have worked in a data center environment. Heat in residential isn't likely to be an issue unless the runs involved have heavy use or as others pointed out, insulation. In bundles in a data center, they tend to be running full tilt. The capacitive and inductive effects also tend to cancel out and are more of an issue with interference between sensitive systems. We use ferrites where that is a concern but generally the bus strips already handle that. Ferrites and capacitors are used to filter noise from a/c systems. Bus strips filter noise to a rack. But back to the original point, heat is the limiting factor for bundles. In a data center you even have engineered runs with integral cooling. But this is industrial not residential.
You’re right, the typical home uses do not generate much heat, but you can’t bet on them being low all of the time. Shielding has little to do with capacitance. The biggest issue I see is drilling too big a hole and weakening the structure. Overall, a good summary.
I think there is a reason this is not addressed in code because there is no problem with the wires in close proximity. The effects of capacitance at 60 Hz is virtually nill. However, high frequency noise often created by power supplies and brushes can be coupled more easily. This is still not typically a problem as these emissions are regulated. Heat is a mild concern, but as you stated total current in a group of wires of a residence is typically very low and further 12 gauge wire is extremely conservatively protected.
I use to work for a telecom company. I can tell you right now that the sheathing on shielded anything doesn’t do crap unless it’s bonded and grounded properly. If you get out in the sticks, especially aerial plant, inductance will light you up. Been there, done that.
Comparing your terminology to mine is fun. My expertise is in electronic design, not electrician. To me a "conductor" is only a single current carrying element. This includes not only wires, but also individual traces on a printed circuit board. A bundle of wires held together with an external jacket (for example romex or NM wire) is always called a cable. A bundle of wires held together in intervals (with, for example zip-ties) is a bundle, more specifically a wire bundle. A bundle of cables held together in intervals is also a bundle, more specifically a cable bundle. You keep referring to a single segment of romex as a conductor and it keeps sounding "wrong" to my ears, but is probably just a jargon difference between two similar looking (from the outside layperson) industries. This example of jargon differences (and my lack of training on electrical code) is why I'll never claim to be an electrician. Keep up the good videos. I'm learning a lot of useful information as a new home owner.
Your use is actually correct for electrician jargon also. NM is a cable, inside it are conductors. You terminate the conductors after all, not the cables. That's certainly how the NEC uses "conductor". But you do also hear electricians say conductor to refer to cables. But then again, those same electricians also just say wire to refer to cables which is actually really annoying when it's completely unclear sometimes what someone is looking for. Oh, you need 12 AWG wire, yes I have some right here for you. What's that, you're looking for 12/2 MC actually? Maybe you should have said that instead of asking for "wire".
I ran into this when I was fixing the wiring in my home. I killed the circuit and then went to work on the outlet and was shocked by the white wire. I was surprised and read the voltage from it. It was about 2 volts dc and quickly went to 0. As a tech who works with capacitors daily recognised this as the white wire getting a charge built on it. Not only is the Capacitve a reality but also Inductance can play a role too.
You probably got shocked from the neutral wire because it was part of a 3 wire circuit and the other circuit was still on and it was sending voltage back on the neutral. Always put a 2 pole breaker on circuits that are sharing a neutral
@@ryanm2084 no, that is what surprised me. it was a singe line. the shock was mor like a large static shock, maybe it was, but in 30 years of wiring it is the first it happened. i investigated and found bundles of wires running together. I put it down to an inductive transformer effect
I think the biggest concern is if the hole is large enough, then it should be protected by a nail plate. Also, if it's too large, construction code might require to reinforce the stub for structural reasons.
@@wim0104 For structural stuff like load-bearing walls, you want to keep holes near the center-line as it is the outside that contributes most to stiffness.
When I saw the 3 Recepticals, "More Cow Bell" came to mind(Wlll Farrell, SNL)Good Video When I Drill holes, I like to drill around a 45 angle to reduce the sharp turn. I do it with Smurff as well. Some helpers won't, I refuse to pull through, they can. Nothing Negative about it, Less Smurf(ENT), Less Wire
Good video. I didn’t hear you mention if the borings are thermally insulated or not. When it comes to quantity of cables in a hole, that plays a big factor. While I agree that most residential/ commercial installs using romex won’t see more than a few amps, you still need to derate them accordingly. The code is clear on that - 334.80. Curious if you see it another way
As an electrical engineering STUDENT I would say the capacitance would be really low... however the inductance could pose a problem if enough cables are grouped together while all being used... they could possibly induce a current in a nearby metal object, possibly hanging or up against the wall and cause a shock to someone who touches it, it could cause the nearby object to heat up from the induced current or cause electrical items nearby to act faulty to name a few... this happens to vehicles as well where sensor wires in a motor are too close to alternator wires or alternating current wires and start acting erratic and throw codes or those sensors (I'm also a mechanic 😅)
Wanna argue all day long - I don’t have that type of time. But De-rating in 310.15 doesn’t have anything to do with capacitance… Back to heat… romex in insulation is about heat. Stacked and bundled also about heat… Environment and ambient temperature heat. Wet vs dry location, heat. Proximity to roof - heat. Current capacity- heat. Inductive heating- heat. So - How many do I put into holes on some of my projects. Outlets and appliances the magic number is 9 CCC’s before having to upgrade the wire size. 1” holes. It was only a few years ago the section for romex added the wording about romex in the same holes in insulation, to refer back to derating in 310.15 - and the magic number is still - 9. On my lighting control Homeworks projects - 8-12/2’s in 1.5” holes - and a handy spreadsheet of load calcs for each conductor pair and each bundle for the 16 CCC’s On my commercial project depending on the cost of wire and conduit these days - it can be cheaper to run daisy chains of subpanels in aluminum with local circuits to keep runs short. But back in the day when copper and pipe were cheap- 16-10’s for 20A circuits in 1.25” conduit half way around the world to the other side of a building. Nothing to do with capacitance, heat.
At some point, drilling larger holes will get to a point where you need nail-plates on every stud because the hole is too close to the edge and now you need to protect the wires.
I like it when you explane code. Look at your table, why would you have to "adjust for ambient temperature" if it has to do with capacitance? Not to argue but a very large effect of transmission lines is the inductance of a 20 mile peace of wire. Yes if you place two 20 mile long wires next to each other you can have a lot of inductive coupling.
Heat dissipation is a real thing. Saw someone once that had a window a/c running on a 100ft extension cord wound on one of those round orange holders. The inner wraps had been melted to a single mass of plastic
I don't think capacitive coupling is going to matter here, because you're going to get much bigger capacitive coupling between the hot and neutral or ground of a single cable. The effect of each additional cable would also get smaller. Going from 10 cables in a bundle to 100 cables in a bundle would have very little effect on the center cables. Heat on the other hand, even if only one conductor is running at max current, having a bunch of extra junk around it can make it harder to dissipate that heat. As the diameter gets bigger, the surface area available to dissipate heat also grows more slowly than the volume of conductor generating heat. If you double the bundle diameter, the surface area doubles, but the number of conductors increases to 4x the original number.
I agree, it is about max current on a single cable/conductor, crowded by other cables/conductors. The jacket/sleeve is why bundling is down to 2 cables for romex, as opposed to many more separate conductors in a conduit?
you can also use this as a reference for anything that uses a bunch of electrical wires since this is a major problem in major audio setups and intricate pc setups, when cross talk or noise is present it can become a major pain to figure out where its coming from so best to set up in such a way where this just cant happen.
Omg capacitive coupling is actually real. Yes the derating tables are excessive but heavy bundling can lead to roasted conductors. I've seen it personally, and I've heard tales of tighly bundled romex gets too hot... its not just a few amps
If there would NEVER be enough current flowing through the NM cable, then we wouldn't run 12 ga on a 20A circuit. Don't forget the customer in the house. What usually doesn't happen...like a house fire...CAN happen if we don't follow code. We usually don't consider the 20 conductor bundling rule except with MC cable in commercial. We also have to consider the hole size if it's a load bearing wall. The NEC cannot be the only book we reference.
I rarely do residential anymore, but when I do, I normally like to use a small paddle bit or auger bit and drill center of the stud to eliminate the need for using nail plates. In a 2x4, that usually means you’re not getting more than 3 cables of 12-2 in there. If I need more wires, I just drill multiple holes and keep them spaced, not only for conductor separation, but for structural purposes as well.
I have scene more and more tract homes using cable stackers and mailing blocks of wood and separating and neatly stapling the wire 1 or 2 or even 3 on top. Looks neater. Nice to see some better quality work. And I have scene bundled wire that was way to hot. Almost to much to touch without gloves. In both commercial and residential work.
The way it was explained to me by one of the engineers in a company I worked for the heat and capacitance could adversely effect arc fault breakers. We were limited to 3 14-2 or 2 12-2 to a 7/8" hole and no sharp,creased bends and staples just holding the jacket.
You appear to miss one important code requirement. Protection of NM Cables. By having a large number of cables (more then 3) they will most likely be too close to the edge of the studs and will require protection with a metal plate. Also by only having just a couple of cables allow some movement or flexibility if a screw or nail did penetrate the hole for the cables.
My house is 123 yrs old and has been rewired twice. The original was knob and tube, most likely done in the early 1900's a good decade after the house was built. Then, probably in the 40's or 50's, rag wire. About 6 years ago, that was updated with 14/2 (with the exception of one circuit.) And, this should piss you all off... on 20 amp breakers. Additionally, 4 bedrooms and a bathroom upstairs are running on one 20 amp breaker. Keep in mind that this was done by a licensed local electrician. I'm trying to find out who that f@#$er is. But the previous owner, who I know well, will not tell me who. She's afraid of getting sued. The kitchen is on one 20 amp breaker, again with 14/2 the rest of the downstairs is also on one 20 amp circuit with 14/2. Insane. The house is a electricians dream with a basement and huge attic and a nice run from basement all the way to attic. Real easy access to everything and, obviously, easy wire pulls. My thought is, why? The crew that did that shit job would litterally have had to work harder to do such a crapy job vs doing it right. Now, I'm not a professional electrician. My experience was a electricians helper when I was taking am electronics course in vocational school in Ohio. The comapny i was working for did residential and commercial and I learned a lot. In new/rewire construction, every room got 20 amp service and was a home run to the panel, the kitchen 2 20 amp circuits. Am i wrong to be pissed off about this? Also, I'm about to run 5 12/2 cables from the basement to the attic to take care of the second floor rooms. Am I hearing this right? In that i don't have to worry about induced voltage from one circuit to another?
Can you make a video on what can happen if you leave conductors damaged? Say you accidentally nicked outside jacket with your drill, or when pulling you stripped outside jacket etc..
as a rule I try to only put 3 wires in a hole. now however it is good practice to let the 10/2 and 10/3 in their own holes. not say you can't put a 14/2 in with them but try not too. also watch the space between holes building codes might have something to say if they are too close to each other.
I'm an electrician apprentice in NH. From what I have been told you can put as many as you can reasonably fit without damaging the insulation for a horizontal run but for vertical holes no more than 5 in a 7/8 hole. we do mostly 7/8 holes because when centered in a 2x4 that just gives you your 1 1/4" spacing. Iv been told the inspector will fail you if you put more than 5 in a 7/8 hole but realistically you cant fit more than 5in a 7/8 hole anyway and 4 is really best. Also I try not to bundle more than 8 conductors in a run.
Here's a question re THHN, not really the romex shown here - is the outer clear plastic sheathing just an expendable layer, expected to be damaged during a pull, or is it actually part of the functionality of the wire?
So just to argue with you for a sec. The capacitance argument you're making is probably why the heat argument is a factor: If a conductor is being impeded by a capacitance issue, that energy has to go somewhere, and the only place any energy ever truly goes is heat. I'm not super familiar with how capacitance actually functions, but if it's acting as any form of resistance in the line, the more the problem increases the more waste heat you'd have / foot. So then having a bundle of lines acting as a blanket over top of the lines in the middle would become a force multiplier for the problem.
As a norwegian electrician. I cant understand why cabel is put in the walls with metal square boxes.. cant u understand that the use of flexible pvc conduit and ROUND pvc boxes is miles smarter and better? It gives u the oppertunity to rewire when walls are closed. Its saves u the time of stripping every cabel to every box by haveing only wires straight in the box. Its way easier for the drywaller cutting out boxes with a roundsaw. U dont have to earth every box, because their pvc.
Would be very helpful to quote code references for everything. The more the actual code is referenced the more likely we will learn. I know this takes time but anyone can just give advice and electricians just think this is true. Quote the code this will make your site better than others
Your video is accurate but there is in fact a code article that says how far from an edge can wires be and that measurement is 2". So, if you bore through a 3 and a 1/2 inch stud a 2" Hole and pack it full of wires, the inside diameter of that hole will be less than 2". A drywall screw could make contact and Pierce the wire This is usually the reason why inspectors say don't have too many wires in the hole without putting nail plates on. In Massachusetts this measurement is reduced 1-1/4 quarter because most sheetrock screws are 1-5/8' long atop half inch sheet rock
Cont. From last message And the other reason is a 2/4 stud is not 4", so there's no place in the middle of the stud you can go and still have 2" from the edge. If the other side of the stud is not getting sheetrocked, like against a basement wall, then bore holes further back.
Bundling too many wires can distort the circuit voltage: A wire running AC will create a time-changing magnetic field around the conductor (Ampere Circuital Law) and nearby CCC's in the presence of a varying EMF will have an opposing voltage induced upon them (Faradays Law). If significant, the voltage could drop low enough to the point where equipment does not work or excess current/heat builds up on conductor and greatly reduces lifespan, i.e. degrading insulation and eventually a fault.
Awesome video, thanks for the great content! Do you have any tips on securing cable in rework situations, like adding 1 gang boxes to an existing residence, and it's supposed to be secured to the nearby stud, but is impractical to nail in due to drywall in the way?
Hey, could you do a video about neutrals. It baffles me why a voltage detector can't pick it up but if you get between two neutrals with a load on it you get hit. I've dealt with this a lot and really is the only time I've gotten hit. I have asked guys in our trade and I don't get many answers. Love your videos keep up the good work!
You should never be separating neutrals with circuits energized....period. If you don't understand why then that should be telling you all you need to know. Study the subject, work under a properly educated and experienced tradesman. Do not underestimate the deadly power of 120 volts, sounds like you have already used up some luck. Study. Go beyond the video like this one, this guy goes off half-cocked on many topics and there are gaps in what is covered which is somewhat dangerous to the inexperienced.
It's been a few years since trade school where we learned a lot of theory but hear me out😄 I thought that having the neutral ran with the hot(or the 2 hots on a 240) kept the load balanced so inductance shouldn't be an issue with others wires near by. Any thoughts? I really like learning and refreshing info from your videos and these comments, thank you!
Current in a wire creates a magnetic field around the wire. The return current in the neutral creates an equal and opposite field which exactly cancels the first. Well not exactly because the two current carrying wires in Romex do not occupy the same physical space but they are very close to each other and the field remaining is very very small. Not true for knob and tube where the wires are separate. Also a big problem in conduit if the two current carrying wires are in different conduits. You can get serious inductive heating if so. The capacitive effect drops off very rapidly with distance and is negligible with Romex. Anything more than a few thousands of an inch of separation pretty much ends any capacitive effect at low frequencies. Capacitors are made with 2 large flat surfaces like metal foil with an ultra thin insulator between them, rolled up and put in a can. Network and audio cables are sheathed with grounded foil because they are very low voltage signals that do not tolerate electrical noise that can be picked up from very high frequency electricity like fluorescent tubes or electronic dimmers. My opinion is the exactly opposite to this video. Bundling rules are all about heat dissipation. I agree most wires in residential carry little current most of the time. But the code is all about houses burning down and if your house doesn't burn down MOST of the time, it only burns down occasionally, that is not good enough. Romex carrying rated load will approach 70 deg C on the wire after 5 minutes in free air. Worse in a wooden hole foamed in. Bundling them together could easily reach the 90 deg C insulation rating even if only one is at full load. Here's an example. You have a space heater plugged in by your TV and electronics on the same circuit so you are running close to 15 Amp rated load. No problem, the thermal circuit in the breaker will never trip. Unfortunately for you, a different cable in the same bundle experiences a dead short when someone plugs in a faulty appliance. Now you've got 1500 amps ( #12=1.6 ohms/1000 ft, say 50 feet of wire @ 120v) but it's only for about 20 mSec or so before the magnetic circuit in the breaker trips. I would guess, seeing how cutting a live #12 Romex will vaporize enough of the metal in my cutters that I need another pair of cutters, this is going to be a problem and at least melt the insulation in some of the Romex.
@@JamesAllen-tj5nu good insight. Would be great if someone could run the scenario as an experiment. See how much it takes before a #12 or #10 give out and melt some insulation. I can see it happening but having solid evidence changes the entire argument
Okay buddy. 334.80 clearly states two or more nm cables sealed with thermal insulation or caulk ampacity adjustment shall be made. So pretty much the nec board made it simple for residential guys to understand code. Simplified it. As an industrial electricians we look at three things voltage drop, adjustment factor and ambient temperature correction factor. So as I see it people at committee made stupid proof for residential electricians two cables and no more. If you want add more Follow 310.15(b)(1) or 310.15(b)(2), 310.15(c)(1) table 310.16 most important factor 334.80 ampacity rule for nm cable. After you follow everything you will realize it cheaper just to run two cables in one whole.
Only time you will see capitance coupling happen is when engineers will provide specifications for specific equipment. Special type of cable will be provided.
I have "center drilled" houses to run home runs to the panel before. Starting with a 3/4" hole at the far end of the house and increasing it to 1 1/4' and 2' as I got closer to the panel. The inspector was quite impressed with my work and complemented me on how neat and clean my work was.
Dang Dustin, you nailed it again. Man I love this show and your truly a mentor of mine. I have been a general contractor for 30+ years and I still find a ton of value in your teachings.
I'm 72 still at it. Great trade to be in. Always something to learn
Like he said, it depends on your local inspector. With 4 conductors in a 1" hole, my inspector
said I could only have 2. --- Drilled a new 3/4" hole and re-ran the conductors. All about getting signed off. ---
I wish this channel was around when I was a first year. I've learned so much in just a few of your videos. Thank you, Sir.
Mostly this is where I learn. More clear than the school I’m attending
Bundling has absolutely zero negative effect on wires/cables. I have examined thousands of cables that spent their lives being bundled and stuffed through holes. The number of failures or installed of damed were....zero.
I spent decades replacing services in AZ. By the time I retired I had done several thousand. Every service is outdoors here and all the cables enter though a hole in the back. It has been done that way way before my time and continues to this day. Why? Because it is a simple and safe installation.
One commentor here mentioned the possibility of INDUCTANCE coupling. If a supposedly dead conductor is not bonded or grounded properly, enough voltage can be induced into it that it can become a problem. (Commentor said he saw someone get electrocuted, although it was in the thousands of volts.)
Hey Swedish electrician here, damn you guys have a easy job. Here in Sweden you have to draw all wires in plastic pipes (when the installation are in walls). But that can also be very useful when you need to change wires/cabels.
It varies. For example, Chicago, IL requires metal conduit in the walls.
@@taylorlightfoot that sucks
@@taylorlightfoot just use MC cable then, no problem.
@@davidsherrill375 those rules have nothing to do with the covering of the conductors in metal - it’s a partnership with the pipe fitters union to have metal conduit and metal pipes. Numerous “union” cities were like that.
Electrical was and in some cases still is “conduit only” with flex only allowed in limited length or conditions.
Remodeling is awesome in the US compared to many places.
I would argue that wall insulation has more effect on the temperature of the conductors than bundling does. Wires in open cavity walls can dissipate heat far easier than having a bat of fiberglass insulation or spray-in insulation around them.
100%
Your right, ive had Home runs goin
Threw the same Hole, and the sheathing has turned brown from
Heat, and Yes after insulator does his Foam
You are both right and wrong.
@@stephenballard2560 care to elaborate?
Well that would fall under the ambient temperature adjustments that you should be considering. If you are an electrician, then you should be factoring it with insulation ratings.
310.15(B)(3)(a) provides a clear definition of multiple cables in a “bundle”. As a general rule, I stick to 3 which derates the conductors by 80%. This allows for other adjustments that might be applied in addition to bundling such as ambient temperature. Thanks for the video.
Well if it’s more than 12 inches hole, conduit then you have to derrate. But for a hole that small you don’t need to derrate at all(12 length
Carpenters sometimes call electricians and plumbers termites.
Agree... I too stick to two cables per 3/4" hole. Occasionally, I have to run three through and just up the hole size to 1". Just makes pulling the cable easier.
Right? Why would you want to fight overstuffed holes to begin with?
Ya at some point it's not practical just dril another hole
@@james10739 And I love getting my money's worth out of my $500 DeWalt hole hog.
@@ericthered9655 that much man I really haven't used it much but I picked up a used Milwaukee hole hawg the smaller on with just 1 speed but it works great but I got it used off eBay for like $120 or something I don't remember but it wasn't near $500
@@james10739 I bought the big flexvolt 60V Max cordless with spare battery. It's really a wonderful drill.
I had an inspector tell me the limit on the amount of romex in the hole was "There wasn't enough room for thermal expansion". I had to stifle a laugh. In his mind I think he expects copper to expand by orders of magnitude when it gets hot.
It expands exponentially..... just with negative exponents. 😂
Not relevant to this electric issue, but when I learned blacksmithing, I was shocked to learn how important thermal expansion was to the work. I assumed it could be ignored because it would be so small, but not so when dealing with the high temps of smithing. When you heat up steel to a typical (yellow hot) forging temp of around 2000 F, a 1 ft length of steel will expand in length about 1/8". So when we are punching holes in hot metal, the expansion becomes very important to compensate for. If you need two holes 12" apart when cold if we measure when hot we will be 1/8" off. So often we mark the metal when cold to deal with this. Because of the very high temps, the expansion becomes significant and important to understand and workaround.
Of course, with loose wires, they never got hot enough for the expansion to create any effect we need to deal with, at least not in residential wiring. It's all about how heat gets trapped and causes temps to rise more. forcing us to derate the current capacity of the wires,
@@CurtWelch you're right, not relevant, but cool nonetheless. I never thought about how much metal expands and contracts on that scale, I'm usually reminded of it when mile long sections of rail kink in the hot sun because they've expanded so much.
yeah, ANYONE is good enough to be an electrical inspector LOL
2:42 I have seen an electrician get killed from that issue, it was actually inductive coupling. The new wire run wasn't grounded running next to a live 7.2KV 3 phase run, which induced enough voltage and current into the new "dead" cable. He grabbed the cable to work on it, not verifying that there was a ground in place, and was electrocuted. That was preventable for sure. 😢
Yeah saw that happen on transmission lines before too. Literally adjacent towers. But it was enough to induce and kill
That's really sad
Yeah, I think the major issue is inductive coupling, not capacitive. In AC inductive coupling can look an awful lot like capacitive coupling until you realize that the capacitive plate sized of two conductors running in parallel is so tiny that really only noise will transfer. Inductive coupling can transfer significant power. Two conductors run in parallel is a simple transformer with a single winding on both the primary and secondary.
well, yeah. you shouldn't run anything close to a High Voltage cable. there used to be a thing- you could run conductors from different voltage systems in the same raceway, as long as everything was rated for the highest voltage present.
@@larrystuder8543 It's still allowed if the voltages are identified as different, but I don't have the code reference. Usually, it's not a problem since most wire we use is rated for 600 volts. This much higher voltage is naturally more dangerous. I'm not sure what precaution is effective, but it doesn't hurt to ALWAYS test with a non-contact voltage tester.
I think some of the limitations are because we used to run 14/2-3 (or even smaller) through walls, while today it’s more common to see 12/2-3 run through walls for additional safety and capacity when needed. The margin of safety between 14 and 12 awg wires is significant, and running 12 awg limits the heat, capacitive resistance, inductive resistance, and expansion those wires might otherwise experience with smaller wires. Running 12 awg is like future-proofing the home. I always recommend running 12 awg, as well as running CAT-6 to every room in the house (and 2-4 runs to every possible media location). CAT-6 is useful in so many ways that it just makes sense to run it before the drywall goes up.
Currently waiting for my coworkers , thanks for being awesome with these videos ! Very nice way to kill time and obtain knowledge 🤟
Me too
@@Attmallard helo
@@Attmallard hello
While we're on the subject of romex running, can you make a video on techniques to rolling out home runs? I've done it now twice, and it just seems like I'm missing some very simple tricks because it takes me FOREVER. Also, what staples do you use and how do you install them? The ones I've tried are a nuisance to put in, and I always end up smashing my thumb multiple times. Would love a video on BASIC techniques of pulling romex, drilling holes; hammering staples and boxes. Just can't seem to find a groove you know
The best way to hammer the staple in without smashing your thumb is by using the Mr Miagi technique. Gently tap with hammer to start staple. Breathe in, breathe out, swing once, thumb no get squish like grape!
do you mean actually uncoiling the wire? you need some kind of spooling device. for the absolute simplest, make a platform out of some kind of scrap material. make a cone in the middle that the coil of romex will fit over, and hang it from the ceiling joist or truss with some kind of swivel so it turns freely. or if you are going to be doing a lot, there are dozens of spooling devices you can buy.
Use needle nose to hold the staple until you get the movement down. No more hulk smashing.
Use a spinner. The white plastic staples are a lot better than the old type.
Well in Canada, our equivalent of roomex comes on reels already, which I am guessing is not always the case in the US. This means any sturdy rod, pipe or whatever is all one needs. That and a stand for the pipe to rest on.
Good video. Something worth mentioning is the derating requirement in 334.80 should the holes be filled with caulk, foam, etc..
Capacitance is not an issue for 60Hz wires. As stated by another commenter, the capacitance between the hot and ground conductors in a Romex cable is greater than the capacitive coupling between arbitrary pairs of Romex cable. The reason for limiting conductors in shared holes in the rules must be some of the other things you mentioned besides the capacitance.
If we assume that Romex has about 20pF per foot, 100' gives about 2000pF, which has a capacitive impedance of about 1 Meg Ohms at 60Hz. That would give about 100 micro-Amps of current flow. If we consider another Romex cable as close as it could be for that same 100' length, the capacitance would probably be ten times less. The result would be insignificant.
Totally screenshotting this!
The capacitance is not in series with the conductor, so it does not impede the current flow in any way. The capacitance is BETWEEN conductors and results in tiny amount of ADDITIONAL current (leakage current). The conductor derating table is there for heat dissipation reasons due to the cables being bundled. Notice that the derating table references ambient temperature, which is a huge hint that they are concerned about temperature rise in the cable.
@@njnear Yes, and the total capacitance is related to total length, so even though there would be a larger capacitance in an exceptionally long run, the capacitance per unit length is only about 20pF (virtually no effect). The resistive losses are also related to unit length, so the heat produced (per unit length) is the key factor. Any time the conductors (and heat) are concentrated into a small area with restricted thermal paths, the temperature rise concern is valid. It is more important for multiple cables in longer enclosed paths because a 2" long hole in a stud may generate more local heat, but the copper conductors will help conduct this heat away from the tight area, spreading the heat out over several more inches, lowering the peak temperature of the conductors (and more importantly, the insulators) in the hole.
Capacitance or inductance is very possible in a 60 hz application. It’s depends on the voltage levels. At normal residential voltage level (ie: 220/120) I will agree it’s not an issue. But, In industrial applications where you have full line voltage (kV) to a switch gear it is a concern that must be keep in mind.
@@sparky_oo1955 Yes, for the power companies with hundreds of miles of transmission lines, they need to be concerned about inductance and capacitance in their designs and controls, but for residential or commercial applications (normal people), the effects at 60Hz can be ignored. Also, the inductance and capacitance don't depend on voltage, but the currents that flow are always Voltage/Impedance.
After a solid year of trying to find an answer to this question. Thank you.
You sir, are a saint. Thank you for taking the time to explain in detail the why’s of everything electrical. I can’t count the many times this has informed or helped me on my daily job as a solar electrician.. coming from residential they’re were a lot of commercial-grade codes or utility code I was unaware of.
I appreciate you since this is the best way I go about not forgetting. it’s just my learning style. It’s gotta be showed and explained to me, can’t always just read from a book 🤣
Your "heat not an issue" argument works fine in typical inside walls, but it's worth considering in outside walls that are insulated. Many years ago, when I was in college, I worked at the local electric utility, and one of the things they asked me to do was to test various types of insulation and their effects on wires. We built a 4-segment wall, ran several conductors through it (14-2 WG Romex, 12-2 Romex, 12 AWG in conduit, 14 AWG in conduit, 14 AWG post and knob) through it, insulated the various sections with different insulating materials (none, fiberglass, cellulose, foam), installed thermocouples to measure the temperatures, and then ran each circuit at various increasing current levels. When we got to 20 amps on the 14-2 Romex circuit (yes, that exceeds NEC but can be a common mistake if 14-2 is connected to a 20A circuit breaker; the utility was aware that some service/panel upgrades used 20A breakers connected to 12 AWG wire at the panel that then connected to existing 14 AWG wire elsewhere in the house), the wall started smoking and caught fire after just 5 minutes of continuous load. The fire started in the foam section, then spread to the cellulose. Needless to say, the test was quickly terminated. The test results were shared with several organizations, and led to some of the electrical and building and insulation code changes we see today.
You make a good point, it's not all about heat. I assumed inductive effects were more prominent, but as you say there is a parallel capacitive effect as well. I'm guessing this could play havoc with the charge on ground wires, and maybe even cause nuisance tripping of AFCI's.
I doubt AFCIs would trip, they're looking for the high frequency characteristics of arcing, and need to ignore the line frequency as it is omnipresent. The more capacitance you have, the lower the resonant frequency will be..
I have a common practice of drilling a 3/4 hole, and if another run is needed, drill another hole. You can fit comfortably 3 runs of 12/2 and 14/3, and 4 runs of 14/2. My biggest concern of overcrowding is not the breathing factor, but drywall screws skewering the run! Though nail plates are used for some reason, a lot of people think longer screws are better to hang drywall, or put up siding.....in my own home, I replaced a junky GE Slimline panel with a nice Square D. The original panel had no main cutoff, though it was installed in 1981, and passed inspe tion (?), and when I purposely forced tripped a Slimline breaker the damn breaker did not trip...so I could have just replaced all the breakers, but with that expense, decided a new panel was needed. Anyway, there was a siding nail stuck inside the service conductor leading to the panel from the meter. I replaced that wire bundle, opened the cover and saw the neutral was indeed poked. Yes, could have energized my whole house exterior....anyway, catch your " act" on the next video!
Huge tip. Flip your drilling direction every 2 or 3 studs and the wire will pull much easier.
I’ll have to try this. Thanks for the tip!
can you elaborate on how/why this works?
@@AndrewBrowner The holes are not straight. Switching directions averages the angles out so the wire has less friction. Try it. The difference is obvious.
I would raise two points. First, capacitive leakage causes some heating. Second, you should wiring not for average use, but for the worst case, because it only takes once for the house to burn down.
Couple years ago, I ran a wood screw into a stud for a shelf bracket…pop went breaker
Opened the wall to find the screw went directly thru the hole, thru the Romex….
No slack to fix it with a wire nut, so I used a crimp butt connector, after crimping I soldered the connector to be safe and covered with heat shrink.
A perfect example of why nail guards are important.
Omg it's such an breath of fresh air bro to see someone not try and overcompljcate these codes and try and act like they're some sort of electrical guru : /
an independent lab ran testing on how many wires can be jammed in a hole without overheating them, so they put various numbers of cables in a hole, foamed the hole, like insulators now always do, and their determination was that you pretty much couldn't exceed 3 cables before you started overheating wires. and capacitance between wires? not a thing I've ever heard of. induced voltage, yes. never capacitance.
and if capacitance is the issue in the wire bundling charts, why is ambient temperature a factor?
You are right, capacitance would be so low with 60 cycle, 240v lines as to be difficult to measure. Even inductance would cancel out as cables tend to twist over distance.
Have the sauce for the study/test?
@@Merescat my code update instructor about 14 years ago.
@@kenbrown2808 No way to verify. I wanted to read it.
@@Merescat sorry. I don't maintain a library for other people. it's not in my scope of practice.
Fwiw, I always carry 3/4 and 1 inch bits. If I know I need to put anything more than a 12/3 and 12/2 in a hole (6/3 alone or 10-3 with 12/2 etc) I always just use the 1 incher. Makes the pulls so much faster, I feel like it saves my customers money. Same logic for anticipating 2 romex per hole. I only do 3+ if there's weird framing that only gives me a single path, but again in those spots I use a 1 inch and ream it if it needs it.
AFAIK, the heat thing is about insulated walls. With the 2020 NEC requiring GFCIs for almost everything, you may want to limit bundling so coupling between cables doesn't cause nuisance trips.
I have worked in a data center environment. Heat in residential isn't likely to be an issue unless the runs involved have heavy use or as others pointed out, insulation. In bundles in a data center, they tend to be running full tilt. The capacitive and inductive effects also tend to cancel out and are more of an issue with interference between sensitive systems. We use ferrites where that is a concern but generally the bus strips already handle that. Ferrites and capacitors are used to filter noise from a/c systems. Bus strips filter noise to a rack. But back to the original point, heat is the limiting factor for bundles. In a data center you even have engineered runs with integral cooling. But this is industrial not residential.
Thanks for the help.
and the comments are gold too.
You’re right, the typical home uses do not generate much heat, but you can’t bet on them being low all of the time.
Shielding has little to do with capacitance. The biggest issue I see is drilling too big a hole and weakening the structure.
Overall, a good summary.
Yes you don't want to weaken the structure. But what weakens the structure more two small holes or one big hole?
I think there is a reason this is not addressed in code because there is no problem with the wires in close proximity. The effects of capacitance at 60 Hz is virtually nill. However, high frequency noise often created by power supplies and brushes can be coupled more easily. This is still not typically a problem as these emissions are regulated. Heat is a mild concern, but as you stated total current in a group of wires of a residence is typically very low and further 12 gauge wire is extremely conservatively protected.
I use to work for a telecom company. I can tell you right now that the sheathing on shielded anything doesn’t do crap unless it’s bonded and grounded properly. If you get out in the sticks, especially aerial plant, inductance will light you up. Been there, done that.
Especially C wire that wasn't twisted when installed, had a co worker yell when he grabbed ends.
Comparing your terminology to mine is fun. My expertise is in electronic design, not electrician. To me a "conductor" is only a single current carrying element. This includes not only wires, but also individual traces on a printed circuit board. A bundle of wires held together with an external jacket (for example romex or NM wire) is always called a cable. A bundle of wires held together in intervals (with, for example zip-ties) is a bundle, more specifically a wire bundle. A bundle of cables held together in intervals is also a bundle, more specifically a cable bundle. You keep referring to a single segment of romex as a conductor and it keeps sounding "wrong" to my ears, but is probably just a jargon difference between two similar looking (from the outside layperson) industries. This example of jargon differences (and my lack of training on electrical code) is why I'll never claim to be an electrician.
Keep up the good videos. I'm learning a lot of useful information as a new home owner.
Your use is actually correct for electrician jargon also. NM is a cable, inside it are conductors. You terminate the conductors after all, not the cables. That's certainly how the NEC uses "conductor". But you do also hear electricians say conductor to refer to cables. But then again, those same electricians also just say wire to refer to cables which is actually really annoying when it's completely unclear sometimes what someone is looking for. Oh, you need 12 AWG wire, yes I have some right here for you. What's that, you're looking for 12/2 MC actually? Maybe you should have said that instead of asking for "wire".
I ran into this when I was fixing the wiring in my home. I killed the circuit and then went to work on the outlet and was shocked by the white wire. I was surprised and read the voltage from it. It was about 2 volts dc and quickly went to 0. As a tech who works with capacitors daily recognised this as the white wire getting a charge built on it. Not only is the Capacitve a reality but also Inductance can play a role too.
You probably got shocked from the neutral wire because it was part of a 3 wire circuit and the other circuit was still on and it was sending voltage back on the neutral. Always put a 2 pole breaker on circuits that are sharing a neutral
@@ryanm2084 no, that is what surprised me. it was a singe line. the shock was mor like a large static shock, maybe it was, but in 30 years of wiring it is the first it happened. i investigated and found bundles of wires running together. I put it down to an inductive transformer effect
Thanks for your videos. I'm retired but still fun to watch.
The NEC codes are 310.15(B)(3)(a) and 310.15(B)(16). Up 9 currect carrying conductors. Don't forget to check with your local codes as well.
I think the biggest concern is if the hole is large enough, then it should be protected by a nail plate. Also, if it's too large, construction code might require to reinforce the stub for structural reasons.
It's the distance to the drywall side that counts; which also leads to a max size for a given 2by size (1" hole in a 2by4 ?)
@@wim0104 For structural stuff like load-bearing walls, you want to keep holes near the center-line as it is the outside that contributes most to stiffness.
Bravo. Master class.
When I saw the 3 Recepticals, "More Cow Bell" came to mind(Wlll Farrell, SNL)Good Video
When I Drill holes, I like to drill around a 45 angle to reduce the sharp turn.
I do it with Smurff as well. Some helpers won't, I refuse to pull through, they can. Nothing Negative about it, Less Smurf(ENT), Less Wire
I love your love for “crazy people” ;)
Good video. I didn’t hear you mention if the borings are thermally insulated or not. When it comes to quantity of cables in a hole, that plays a big factor. While I agree that most residential/ commercial installs using romex won’t see more than a few amps, you still need to derate them accordingly. The code is clear on that - 334.80. Curious if you see it another way
As an electrical engineering STUDENT I would say the capacitance would be really low... however the inductance could pose a problem if enough cables are grouped together while all being used... they could possibly induce a current in a nearby metal object, possibly hanging or up against the wall and cause a shock to someone who touches it, it could cause the nearby object to heat up from the induced current or cause electrical items nearby to act faulty to name a few... this happens to vehicles as well where sensor wires in a motor are too close to alternator wires or alternating current wires and start acting erratic and throw codes or those sensors (I'm also a mechanic 😅)
Very informative video! Exactly what I wanted to know!
Wanna argue all day long - I don’t have that type of time. But De-rating in 310.15 doesn’t have anything to do with capacitance…
Back to heat… romex in insulation is about heat. Stacked and bundled also about heat… Environment and ambient temperature heat. Wet vs dry location, heat. Proximity to roof - heat. Current capacity- heat. Inductive heating- heat.
So - How many do I put into holes on some of my projects. Outlets and appliances the magic number is 9 CCC’s before having to upgrade the wire size. 1” holes. It was only a few years ago the section for romex added the wording about romex in the same holes in insulation, to refer back to derating in 310.15 - and the magic number is still - 9.
On my lighting control Homeworks projects - 8-12/2’s in 1.5” holes - and a handy spreadsheet of load calcs for each conductor pair and each bundle for the 16 CCC’s
On my commercial project depending on the cost of wire and conduit these days - it can be cheaper to run daisy chains of subpanels in aluminum with local circuits to keep runs short. But back in the day when copper and pipe were cheap- 16-10’s for 20A circuits in 1.25” conduit half way around the world to the other side of a building. Nothing to do with capacitance, heat.
I work in UT, typically use a 7/8" Bosch bit and my master electrician says he doesn't want to see more than three wires per hole.
Same
NEAT and WORKMANLIKE manner... that's the goal! Your work practices dictate installing a safe install for the end user.
At some point, drilling larger holes will get to a point where you need nail-plates on every stud because the hole is too close to the edge and now you need to protect the wires.
Everyone: “How many wires can you fit in each hole????”
Dustin: “All of them.”
"How many you got?"😉
Excellent topic Dustin, thanks bro!
I like it when you explane code. Look at your table, why would you have to "adjust for ambient temperature" if it has to do with capacitance? Not to argue but a very large effect of transmission lines is the inductance of a 20 mile peace of wire. Yes if you place two 20 mile long wires next to each other you can have a lot of inductive coupling.
Question: getting ready to wire a shop - Better to use Romex or single wires? Your opinion?
Could you do a video on various staple? Lengths, types etc.?
Thank you for sharing your knowledge.
Great video Dustin keep them coming great information!!!
Heat dissipation is a real thing. Saw someone once that had a window a/c running on a 100ft extension cord wound on one of those round orange holders. The inner wraps had been melted to a single mass of plastic
Thanks again for all u do … it’s incredible how much u share
As usual excellent video. . A happy inspector is an easier day for any electrician. Give those conductors some space .
I don't think capacitive coupling is going to matter here, because you're going to get much bigger capacitive coupling between the hot and neutral or ground of a single cable. The effect of each additional cable would also get smaller. Going from 10 cables in a bundle to 100 cables in a bundle would have very little effect on the center cables.
Heat on the other hand, even if only one conductor is running at max current, having a bunch of extra junk around it can make it harder to dissipate that heat. As the diameter gets bigger, the surface area available to dissipate heat also grows more slowly than the volume of conductor generating heat. If you double the bundle diameter, the surface area doubles, but the number of conductors increases to 4x the original number.
I agree, it is about max current on a single cable/conductor, crowded by other cables/conductors.
The jacket/sleeve is why bundling is down to 2 cables for romex, as opposed to many more separate conductors in a conduit?
...and leaving gaps between cable assemblies in open busway and wire-tray/basket?
you can also use this as a reference for anything that uses a bunch of electrical wires since this is a major problem in major audio setups and intricate pc setups, when cross talk or noise is present it can become a major pain to figure out where its coming from so best to set up in such a way where this just cant happen.
I agree with this. I always do 2-3 wires per 7/8 hole if it’s 14/2 almost always 2 per hole for 12/2
Omg capacitive coupling is actually real. Yes the derating tables are excessive but heavy bundling can lead to roasted conductors. I've seen it personally, and I've heard tales of tighly bundled romex gets too hot... its not just a few amps
If there would NEVER be enough current flowing through the NM cable, then we wouldn't run 12 ga on a 20A circuit. Don't forget the customer in the house. What usually doesn't happen...like a house fire...CAN happen if we don't follow code. We usually don't consider the 20 conductor bundling rule except with MC cable in commercial. We also have to consider the hole size if it's a load bearing wall. The NEC cannot be the only book we reference.
I rarely do residential anymore, but when I do, I normally like to use a small paddle bit or auger bit and drill center of the stud to eliminate the need for using nail plates. In a 2x4, that usually means you’re not getting more than 3 cables of 12-2 in there. If I need more wires, I just drill multiple holes and keep them spaced, not only for conductor separation, but for structural purposes as well.
nice video thanks for the info!
All them can fit, but code depicts the correct answer
I have scene more and more tract homes using cable stackers and mailing blocks of wood and separating and neatly stapling the wire 1 or 2 or even 3 on top. Looks neater. Nice to see some better quality work. And I have scene bundled wire that was way to hot. Almost to much to touch without gloves. In both commercial and residential work.
I really enjoy your channel! You are truly professional and I’m always learning something new from you. Thanks for sharing!
Awesome looking service loops.
The way it was explained to me by one of the engineers in a company I worked for the heat and capacitance could adversely effect arc fault breakers. We were limited to 3 14-2 or 2 12-2 to a 7/8" hole and no sharp,creased bends and staples just holding the jacket.
I've never had that affect arc fault breakers and I usually run 3 wires per hole
If the bend in the romex is too sharp it's actually a code violation
You appear to miss one important code requirement. Protection of NM Cables. By having a large number of cables (more then 3) they will most likely be too close to the edge of the studs and will require protection with a metal plate. Also by only having just a couple of cables allow some movement or flexibility if a screw or nail did penetrate the hole for the cables.
Another great video Dustin .
My house is 123 yrs old and has been rewired twice. The original was knob and tube, most likely done in the early 1900's a good decade after the house was built.
Then, probably in the 40's or 50's, rag wire. About 6 years ago, that was updated with 14/2 (with the exception of one circuit.) And, this should piss you all off... on 20 amp breakers. Additionally, 4 bedrooms and a bathroom upstairs are running on one 20 amp breaker. Keep in mind that this was done by a licensed local electrician. I'm trying to find out who that f@#$er is. But the previous owner, who I know well, will not tell me who. She's afraid of getting sued.
The kitchen is on one 20 amp breaker, again with 14/2 the rest of the downstairs is also on one 20 amp circuit with 14/2. Insane.
The house is a electricians dream with a basement and huge attic and a nice run from basement all the way to attic. Real easy access to everything and, obviously, easy wire pulls.
My thought is, why? The crew that did that shit job would litterally have had to work harder to do such a crapy job vs doing it right.
Now, I'm not a professional electrician. My experience was a electricians helper when I was taking am electronics course in vocational school in Ohio. The comapny i was working for did residential and commercial and I learned a lot. In new/rewire construction, every room got 20 amp service and was a home run to the panel, the kitchen 2 20 amp circuits.
Am i wrong to be pissed off about this? Also, I'm about to run 5 12/2 cables from the basement to the attic to take care of the second floor rooms.
Am I hearing this right? In that i don't have to worry about induced voltage from one circuit to another?
This was never covered in any electrical class I've ever had. Thanks.
Yes, I'm very open to more training.
Can you make a video on what can happen if you leave conductors damaged? Say you accidentally nicked outside jacket with your drill, or when pulling you stripped outside jacket etc..
Great insight by the so called NERDS : ) Outstanding!!
Good point.
Thank you.
as a rule I try to only put 3 wires in a hole. now however it is good practice to let the 10/2 and 10/3 in their own holes. not say you can't put a 14/2 in with them but try not too. also watch the space between holes building codes might have something to say if they are too close to each other.
I'm an electrician apprentice in NH. From what I have been told you can put as many as you can reasonably fit without damaging the insulation for a horizontal run but for vertical holes no more than 5 in a 7/8 hole. we do mostly 7/8 holes because when centered in a 2x4 that just gives you your 1 1/4" spacing. Iv been told the inspector will fail you if you put more than 5 in a 7/8 hole but realistically you cant fit more than 5in a 7/8 hole anyway and 4 is really best. Also I try not to bundle more than 8 conductors in a run.
Great video 👍👍 I truly agree with you! Keep pumping those videos out you're an awesome teacher!
THANK YOU 🙏!! Another great video!!
Can you put 2 12-2 wires in a 1/2" hole in a stud? Great vid.
Here's a question re THHN, not really the romex shown here - is the outer clear plastic sheathing just an expendable layer, expected to be damaged during a pull, or is it actually part of the functionality of the wire?
👍Great video as always👍
Thank you
You're awesome. Really enjoy these videos.
So just to argue with you for a sec. The capacitance argument you're making is probably why the heat argument is a factor: If a conductor is being impeded by a capacitance issue, that energy has to go somewhere, and the only place any energy ever truly goes is heat. I'm not super familiar with how capacitance actually functions, but if it's acting as any form of resistance in the line, the more the problem increases the more waste heat you'd have / foot. So then having a bundle of lines acting as a blanket over top of the lines in the middle would become a force multiplier for the problem.
Good to know!
As a norwegian electrician. I cant understand why cabel is put in the walls with metal square boxes.. cant u understand that the use of flexible pvc conduit and ROUND pvc boxes is miles smarter and better?
It gives u the oppertunity to rewire when walls are closed.
Its saves u the time of stripping every cabel to every box by haveing only wires straight in the box.
Its way easier for the drywaller cutting out boxes with a roundsaw.
U dont have to earth every box, because their pvc.
Thanks for sharing 👍🏼
The most I’ve seen is 3 and that was impressive
Would be very helpful to quote code references for everything. The more the actual code is referenced the more likely we will learn. I know this takes time but anyone can just give advice and electricians just think this is true.
Quote the code this will make your site better than others
Your video is accurate but there is in fact a code article that says how far from an edge can wires be and that measurement is 2". So, if you bore through a 3 and a 1/2 inch stud a 2" Hole and pack it full of wires, the inside diameter of that hole will be less than 2". A drywall screw could make contact and Pierce the wire This is usually the reason why inspectors say don't have too many wires in the hole without putting nail plates on. In Massachusetts this measurement is reduced 1-1/4 quarter because most sheetrock screws are 1-5/8' long atop half inch sheet rock
Cont. From last message
And the other reason is a 2/4 stud is not 4", so there's no place in the middle of the stud you can go and still have 2" from the edge. If the other side of the stud is not getting sheetrocked, like against a basement wall, then bore holes further back.
Bundling too many wires can distort the circuit voltage: A wire running AC will create a time-changing magnetic field around the conductor (Ampere Circuital Law) and nearby CCC's in the presence of a varying EMF will have an opposing voltage induced upon them (Faradays Law). If significant, the voltage could drop low enough to the point where equipment does not work or excess current/heat builds up on conductor and greatly reduces lifespan, i.e. degrading insulation and eventually a fault.
Why isn’t there more funny comments! One in a hole is more than enough when the wire is the proper size
What is that orange cable with a black stripe?
Awesome video, thanks for the great content! Do you have any tips on securing cable in rework situations, like adding 1 gang boxes to an existing residence, and it's supposed to be secured to the nearby stud, but is impractical to nail in due to drywall in the way?
I believe the code says you don't have to staple in that scenario because it would be impractical to.
Hey, could you do a video about neutrals. It baffles me why a voltage detector can't pick it up but if you get between two neutrals with a load on it you get hit. I've dealt with this a lot and really is the only time I've gotten hit. I have asked guys in our trade and I don't get many answers. Love your videos keep up the good work!
Jake...good idea and true!
You should never be separating neutrals with circuits energized....period. If you don't understand why then that should be telling you all you need to know. Study the subject, work under a properly educated and experienced tradesman. Do not underestimate the deadly power of 120 volts, sounds like you have already used up some luck. Study. Go beyond the video like this one, this guy goes off half-cocked on many topics and there are gaps in what is covered which is somewhat dangerous to the inexperienced.
It's been a few years since trade school where we learned a lot of theory but hear me out😄 I thought that having the neutral ran with the hot(or the 2 hots on a 240) kept the load balanced so inductance shouldn't be an issue with others wires near by. Any thoughts? I really like learning and refreshing info from your videos and these comments, thank you!
Current in a wire creates a magnetic field around the wire. The return current in the neutral creates an equal and opposite field which exactly cancels the first. Well not exactly because the two current carrying wires in Romex do not occupy the same physical space but they are very close to each other and the field remaining is very very small. Not true for knob and tube where the wires are separate. Also a big problem in conduit if the two current carrying wires are in different conduits. You can get serious inductive heating if so.
The capacitive effect drops off very rapidly with distance and is negligible with Romex. Anything more than a few thousands of an inch of separation pretty much ends any capacitive effect at low frequencies. Capacitors are made with 2 large flat surfaces like metal foil with an ultra thin insulator between them, rolled up and put in a can. Network and audio cables are sheathed with grounded foil because they are very low voltage signals that do not tolerate electrical noise that can be picked up from very high frequency electricity like fluorescent tubes or electronic dimmers.
My opinion is the exactly opposite to this video. Bundling rules are all about heat dissipation. I agree most wires in residential carry little current most of the time. But the code is all about houses burning down and if your house doesn't burn down MOST of the time, it only burns down occasionally, that is not good enough. Romex carrying rated load will approach 70 deg C on the wire after 5 minutes in free air. Worse in a wooden hole foamed in. Bundling them together could easily reach the 90 deg C insulation rating even if only one is at full load.
Here's an example. You have a space heater plugged in by your TV and electronics on the same circuit so you are running close to 15 Amp rated load. No problem, the thermal circuit in the breaker will never trip. Unfortunately for you, a different cable in the same bundle experiences a dead short when someone plugs in a faulty appliance. Now you've got 1500 amps ( #12=1.6 ohms/1000 ft, say 50 feet of wire @ 120v) but it's only for about 20 mSec or so before the magnetic circuit in the breaker trips. I would guess, seeing how cutting a live #12 Romex will vaporize enough of the metal in my cutters that I need another pair of cutters, this is going to be a problem and at least melt the insulation in some of the Romex.
@@JamesAllen-tj5nu well said good sir had no idea the wires in free air could heat up so much and quickly on rated load.
@@JamesAllen-tj5nu good insight. Would be great if someone could run the scenario as an experiment. See how much it takes before a #12 or #10 give out and melt some insulation. I can see it happening but having solid evidence changes the entire argument
Okay buddy.
334.80 clearly states two or more nm cables sealed with thermal insulation or caulk ampacity adjustment shall be made.
So pretty much the nec board made it simple for residential guys to understand code. Simplified it.
As an industrial electricians we look at three things voltage drop, adjustment factor and ambient temperature correction factor.
So as I see it people at committee made stupid proof for residential electricians two cables and no more. If you want add more
Follow 310.15(b)(1) or 310.15(b)(2), 310.15(c)(1) table 310.16 most important factor 334.80 ampacity rule for nm cable. After you follow everything you will realize it cheaper just to run two cables in one whole.
Only time you will see capitance coupling happen is when engineers will provide specifications for specific equipment. Special type of cable will be provided.
Well said.