Great job Ryan. I see time from time several NM cables entering through a nipple, typically at the back of cabinet. Seems that it has been allowed by the AHJ's in some areas, but I always thought it violated 312.5.
Greetings Ryan, Excellent training as always. I just wanted to add that I find it easier when working with elliptical shaped cables to use "A = (π/4) × D2" ...sorry cant do a little 2...LOL.. To show Diameter squared but you get the point. As long as they know the diameter ter of the cable they are good to go. Guess all these work as well: π (Pi) times the Radius squared: A = π r2 or, when you know the Diameter: A = (π/4) × D2 or, when you know the Circumference: A = C2 / 4π Now if I can just figure out how to show a small 2 I am all set...LOL...but again great training fella and keep up the great work.
Convention is to use the symbol above the 6 on the keyboard, to indicate exponents. A = pi*r^2 is the way to write it, without resorting to the character map or special formatting.
Let me shake things up a bit. There is nothing in 312.5(C) that states that cables rated for wet locations cannot enter from the back of an outdoor surface mount panel through a chase nipple, for example. "312.5(C) Cables. Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure." That requirement is followed by an exception: "Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met: ..." . Maybe someone is thinking: "but they have to be secured to the panel and you are not using a cable clamp if you run through a chase nipple!" But, 312 does not say how they have to be secured to the panel, and as such it appears that the method does not even have to be with listed equipment. 312 simply states that it has to be secured. Therefore, after passing into the panel, apparently the cable can be securely tied down/clamped within the box. Also the chase nipple must protect against abrasion per 312. Although knockout clamps are the standard for indoor panels for obvious reasons, I do not believe that they are required per NEC. So for example, 312 does not prevent running SER and UF through the back and securing it inside the panel. Please tell me why I'm wrong. Fire away!
Here's a question. In my garage I have some 1/2in EMT coming from the ceiling to standard surface mounted boxes, handy boxes and 4x4's. I run #12 Romex from the panel or an accessible J-box in garage the attic to the EMT stub using a Romex clamp connector via a threaded bushing. At the point where the Romex enters the EMT, I strip the jacket all the way into the end box. Remember it is clamped at the start of the EMT stub. Is this legal? I always thought you weren't allowed to run jacketed cable including Romex inside EMT. And most Romex these days is just THHN under the outer jacket although it's not labeled as such.
I see this application used on existing cabinets at the back of houses all the time in Florida. Conduit coming down from soffit. Many code violations in one. The conduit being stopped inside the soffit would be one, another would be strapping within 6 inches because you wouldn't be able to physically get to that point where the pitch of the roof is while at the same time, keeping the conduit inside the soffit to keep your romex from weather and or physical damage. Always overfilled and never having a fitting on the end inside of the soffit... Not once have I had an inspector pick on it though... Just curious as to what other electricians would do in this scenario? Have the contractor build something around the top of the cabinet? Tear out the inside wall and run the cables in behind the panel? (I've done this before where the wall was already being replaced) I've never been called out for using the existing sleeve to add circuits but I'm sure it is bound to happen sooner or later. I would say making sure fill is met and fittings are at least installed on the end as well as filling the end would be well enough but you'd still have some criteria not met at that point. Worried about a current install on an old house in Florida. Appreciate the advice.
Subscribed!!! Big question! What NM connector is listed for multiple wires? The problem I keep having is is blasting a surface meter main, when there are limited knock outs on the back. To keep it looking clean, we want to come through the back of the enclosure where they have 2 in knockouts. Any suggestions? Or what NM connectors do you recommend?
Ryan, this was an old video of yours but relevant and explained so well. Using the conversion to determine the area of a cable based on it’s width is overlooked or maybe ignored at times. This is related to pulling NM in conduit (permitted but why would you do it?). And it is permitted so long as you meet all other NEC rules related to conduit including “fill limitations.” Multiple flat and neatly stacked NM cables entering or exiting a conduit may look fine but an inspector can spoil your day.
Idk if anybody noticed but on you multiplied wrong, you had said that there was 7 12/2s and 11 14/2s and you actually did it the other way. Either way, great video!
What about surface mounted panels on the outside of a residential home, can NM cable from inside the wall behind the panel enter into the back of the surface mounted panel if the panel is outside?
Great video, thanks Ryan I have a question for you , what is your take on these AC mini split systems . The circuit is run out to the condensing unit outside and then a cable (TC cable art 336) is run between the outside condenser and the evaporator inside I work in a local jurisdiction here in Colorado and I have brought this up to the attention of the other inspectors in the team because the cable runs 220 volts to operate the inside unit thru an additional control wire they don’t seam to think that this is big deal in that this cable is being installed by mechanical technicians and not getting inspected and no permits being pulled what is your take
The HVAC company I work for uses 14/4 SOOW cable for mini split indoor unit power and control. Mitsubishi units only need L1 and L2 for 230 volt power plus a third 30V dc conductor for communication plus the ground. It may be that power control cables for these mini split units are considered as part of the total system and while they are field installed, are covered under the equipment listing. LG specifies 4C/18 wire for some indoor unit com and power wiring which is basically alarm wire. Indoor units are rated at around 1.8 -2 amps RLA so I assume this is OK since it is listed. I still use the SO cord for LG installs (it's far more rodent proof).
@@MrGuitguy sorry. Was always taught that so called extension cords such as type SO SOOW SJO etc can never be used as permanent wiring. Better off using type MC AC cable for this.
All older type NM ( before around 1985 ) and newest type NMB cable since at least 1970 were all made with a bare EGC wire. No such thing as Romex in any edition of NEC. Romex like wire nut are brand names. Forget what size NMB cable starts using a reduced EGC. Think #6 & larger has the reduced EGC. Did only industrial electrical work last 35 years before I retired so did not work with. "Romex" much but tons of MC cable & conduit.
I engineer broadcast facilities and data centers. A trick I have used for years and has always been approved in several states is as follows. We use 225a flush mounted main breaker panels. From that we run three or four 3in conduits stubbing out under raised flooring terminating to 12x12x6 or 12x12x4 pull boxes. From here we run Sealtite or MC spliced to THHN wire in the pull box to equipment rack power strips or outlets. The idea here is future power upgrades or changes are very easy without having to open the wall.
Hi Ryan, In 7:33 you showed a graph showing the diameters I noticed that 12/3 has .345 diameter while 12/2 has .450 in this situation how would you figure this out because you’d think it would be bigger if there was a extra wire. Thank you for explaining this tough subject so I can understand it I really appreciate it.
Hi Connor. When this was made, 12-3 was a round cable and 12-2 was flat. I'm sure if found a newer version it would show a larger diameter, based on 12-3 being flat once again.
Ok finally got it, the diameter would’ve been wider if 12-3 was flat because the extra wire would have been placed beside the others. But seeing how it is round they are stacked more like two on top of the other making the diameter not as wide. It took me a second, cause I couldn’t figure why there is more wires but less diameter but now I do. Thank you Ryan
Actually subject to local electrical jurisdiction, that supercedes the NEC. And the reason you don't use pvc electrical pipe exposed is because if it catches on fire, it becomes toxic. You should never used pvc exposed, it can terminate underneath switchgear where it is totally enclosed.
Yes. You can use the 90 degree C column of Table 310.16 for ampacity correction, but if you have more than nine current carrying conductors it is going to be a problem. HOWEVER, we can also use 310.14(A)(2)'s Exception [310.15(A)(2) in older books] and make the issue go away completely.
@@RyanJacksonElectrical I thought there was also an exception for that for a nipple (under 24"), and as long as at least one of the ends were open. The idea being that a nipple with at least one open end will not build up a big bunch of heat. The end of the nipple outside of the enclosure still has to be sealed, like in this example video.
Ryan Jackson I had 48 12 thhn in a 2 1/2 pvc they made me remove them down to 20 wires and increase the size to 10 which I argued that was would stop someone from then installing 30 amp breakers on those circuits your opinion would be very welcomed
Yeah, the exception I posted woukd get you out of it. As far as changing the breakers, that is true anytime we increase for voltage drop too. We can't possibly make rules based on people changing the rating of an overcurrent device.
@@RyanJacksonElectrical we can also label/note on the wires on the inside as well as the outside of the panel why the wires are oversized and not to increase the breaker size. Even if there was something in the code stressing something like this,, we all know the trunk slammers and weekend warriors go by"it works, it must be right" thought. Collectively an amendment to the NEC for a change listing that issue can be submitted as well.
28,000 views over a years time and only 2 people mention the blatantly obvious miscalculations. Yet so many give thanks and congratulate his good work. Not to say his explanation is not well put together or his formulas are not sound. Just he made a simple human error when plugging his values into the equations.
Your calculations are wrong.... Your initial wire count was (11) 14-2 and (7) 12-2. How ever when calculating your area you calculated for (11) 12-2 and (7) 14-2
Good except areas are expressed in SQUARE inches, and volumes are expressed in CUBIC inches…not just “Inches”. 2.58” is a linear quantity not an area, or a volume. I know what you were saying but I guarantee there were a bunch of watchers of this who were confused. Those code sections deal with AREA… square inches. So say that.
@@BattleToads1990 yes, especially considering they are different in all state lol and they are made by people that have never worked a minute in the field
The only difference state to state is which version NEC is currently adopted. Its still the NEC, the minimum that we follow that comes with doing electrical work safely, consistently. There's no whining in electrical work either, do it right or don't do it at all...
@@NA0533 be sure to pick up a copy of the NEC. You will find a form that in the back that you can submit any changes or additions to the code. Most people on the code panels started out in the field and worked there way onto one of the commitees. Like everything else, you can be part of a change if you want to!
![Raceways Exposed to Different Temperatures [300.7, 2020 NEC]](/img/1.gif)
Excellent explanation. Would be nice to see videos like these for each code in the NEC, but it would probably take forever. I just subscribed.
Excellent videos. Clear and concise explanations.
Thank you for clearly explaining this section, well done!
Thank you , As a Houston master electrician this is the kind of things we due if the field all the time .
Great job Ryan. I see time from time several NM cables entering through a nipple, typically at the back of cabinet. Seems that it has been allowed by the AHJ's in some areas, but I always thought it violated 312.5.
Greetings Ryan,
Excellent training as always. I just wanted to add that I find it easier when working with elliptical shaped cables to use "A = (π/4) × D2" ...sorry cant do a little 2...LOL.. To show Diameter squared but you get the point. As long as they know the diameter ter of the cable they are good to go.
Guess all these work as well:
π (Pi) times the Radius squared: A = π r2
or, when you know the Diameter: A = (π/4) × D2
or, when you know the Circumference: A = C2 / 4π
Now if I can just figure out how to show a small 2 I am all set...LOL...but again great training fella and keep up the great work.
Convention is to use the symbol above the 6 on the keyboard, to indicate exponents. A = pi*r^2 is the way to write it, without resorting to the character map or special formatting.
@@carultch LOL....OK..Thanks
Does doing this reduce the ampacity? Or do i have to debate conductors?
Thanks for the information 👍,grateful.
Let me shake things up a bit. There is nothing in 312.5(C) that states that cables rated for wet locations cannot enter from the back of an outdoor surface mount panel through a chase nipple, for example. "312.5(C) Cables. Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure." That requirement is followed by an exception: "Cables with entirely nonmetallic sheaths shall be permitted to
enter the top of a surface-mounted enclosure through one or more
nonflexible raceways not less than 450 mm (18 in.) and not more than
3.0 m (10 ft) in length, provided all of the following conditions are
met: ..." . Maybe someone is thinking: "but they have to be secured to the panel and you are not using a cable clamp if you run through a chase nipple!" But, 312 does not say how they have to be secured to the panel, and as such it appears that the method does not even have to be with listed equipment. 312 simply states that it has to be secured. Therefore, after passing into the panel, apparently the cable can be securely tied down/clamped within the box. Also the chase nipple must protect against abrasion per 312. Although knockout clamps are the standard for indoor panels for obvious reasons, I do not believe that they are required per NEC. So for example, 312 does not prevent running SER and UF through the back and securing it inside the panel. Please tell me why I'm wrong. Fire away!
Here's a question. In my garage I have some 1/2in EMT coming from the ceiling to standard surface mounted boxes, handy boxes and 4x4's. I run #12 Romex from the panel or an accessible J-box in garage the attic to the EMT stub using a Romex clamp connector via a threaded bushing. At the point where the Romex enters the EMT, I strip the jacket all the way into the end box. Remember it is clamped at the start of the EMT stub. Is this legal? I always thought you weren't allowed to run jacketed cable including Romex inside EMT. And most Romex these days is just THHN under the outer jacket although it's not labeled as such.
I see this application used on existing cabinets at the back of houses all the time in Florida. Conduit coming down from soffit. Many code violations in one. The conduit being stopped inside the soffit would be one, another would be strapping within 6 inches because you wouldn't be able to physically get to that point where the pitch of the roof is while at the same time, keeping the conduit inside the soffit to keep your romex from weather and or physical damage. Always overfilled and never having a fitting on the end inside of the soffit... Not once have I had an inspector pick on it though... Just curious as to what other electricians would do in this scenario? Have the contractor build something around the top of the cabinet? Tear out the inside wall and run the cables in behind the panel? (I've done this before where the wall was already being replaced) I've never been called out for using the existing sleeve to add circuits but I'm sure it is bound to happen sooner or later. I would say making sure fill is met and fittings are at least installed on the end as well as filling the end would be well enough but you'd still have some criteria not met at that point. Worried about a current install on an old house in Florida. Appreciate the advice.
You made this crystal clear . . . thanks!
Glad I heard about this channel. Subscribed!
Thanks brother!
Subscribed!!!
Big question! What NM connector is listed for multiple wires? The problem I keep having is is blasting a surface meter main, when there are limited knock outs on the back. To keep it looking clean, we want to come through the back of the enclosure where they have 2 in knockouts. Any suggestions? Or what NM connectors do you recommend?
Ryan, this was an old video of yours but relevant and explained so well. Using the conversion to determine the area of a cable based on it’s width is overlooked or maybe ignored at times. This is related to pulling NM in conduit (permitted but why would you do it?). And it is permitted so long as you meet all other NEC rules related to conduit including “fill limitations.” Multiple flat and neatly stacked NM cables entering or exiting a conduit may look fine but an inspector can spoil your day.
Where did you find the NM-B chart?
All your free videos are fun to watch.
Nice job explaining the calculation
Idk if anybody noticed but on you multiplied wrong, you had said that there was 7 12/2s and 11 14/2s and you actually did it the other way. Either way, great video!
Great video .. just have one question .. how would you calculate cables that are not elliptical like 10/3 8/3 6/3 ? TIA
PI times radius sqaured.
What about surface mounted panels on the outside of a residential home, can NM cable from inside the wall behind the panel enter into the back of the surface mounted panel if the panel is outside?
Good job , I wish I had your math skills
Excellent video.
Hi.ryan.i got question.what is the minimun clearance of de box????.abel.miami
Is wire fill in pipe a “getting damaged when pulling” issue? Or is it a “ambient heat” issue
Mostly the latter, but a tiny bit of the former. (if you're stuffing so much cable in there it becomes hard to pull, you may want to rethink it.)
So. You cant just jam 30 cables in a 2" TA and enter the back of a 3r panel.
LOL right?
Great video, thanks Ryan
I have a question for you , what is your take on these AC mini split systems . The circuit is run out to the condensing unit outside and then a cable (TC cable art 336) is run between the outside condenser and the evaporator inside I work in a local jurisdiction here in Colorado and I have brought this up to the attention of the other inspectors in the team because the cable runs 220 volts to operate the inside unit thru an additional control wire they don’t seam to think that this is big deal in that this cable is being installed by mechanical technicians and not getting inspected and no permits being pulled what is your take
The HVAC company I work for uses 14/4 SOOW cable for mini split indoor unit power and control. Mitsubishi units only need L1 and L2 for 230 volt power plus a third 30V dc conductor for communication plus the ground. It may be that power control cables for these mini split units are considered as part of the total system and while they are field installed, are covered under the equipment listing. LG specifies 4C/18 wire for some indoor unit com and power wiring which is basically alarm wire. Indoor units are rated at around 1.8 -2 amps RLA so I assume this is OK since it is listed. I still use the SO cord for LG installs (it's far more rodent proof).
@@MrGuitguy Was aleays taught that
@@MrGuitguy sorry. Was always taught that so called extension cords such as type SO SOOW SJO etc can never be used as permanent wiring. Better off using type MC AC cable for this.
Never was any good at math but I like most pies. So I usually up size the pipe 😁
Loving it
So you can ignore the ampacity derating altogether?
Is there somewhere in the code giving you the area for nm cables? That was a question on the exam I had and was like whaaaattt?
No. It would vary by manufacturer.
Ryan, can you tell me why is it commun to use ROMEX 2-14 or 2-12, don´t you use EGC in those circuits?
You must use the bare wire for grounding in ALL 14/2 14/3 12/2 12/3 10/2 in NM cable.
All older type NM ( before around 1985 ) and newest type NMB cable since at least 1970 were all made with a bare EGC wire. No such thing as Romex in any edition of NEC. Romex like wire nut are brand names. Forget what size NMB cable starts using a reduced EGC. Think #6 & larger has the reduced EGC. Did only industrial electrical work last 35 years before I retired so did not work with. "Romex" much but tons of MC cable & conduit.
thinking you figures 11 12-2 , 7 14-2 when in video around 6: 45 mark you said 11 14-2 and 7 12-2 , but thanks
Great video Ryan! As always. ;)
Oh and excellent video BTW!!
I engineer broadcast facilities and data centers. A trick I have used for years and has always been approved in several states is as follows. We use 225a flush mounted main breaker panels. From that we run three or four 3in conduits stubbing out under raised flooring terminating to 12x12x6 or 12x12x4 pull boxes. From here we run Sealtite or MC spliced to THHN wire in the pull box to equipment rack power strips or outlets. The idea here is future power upgrades or changes are very easy without having to open the wall.
Hi Ryan, In 7:33 you showed a graph showing the diameters I noticed that 12/3 has .345 diameter while 12/2 has .450 in this situation how would you figure this out because you’d think it would be bigger if there was a extra wire. Thank you for explaining this tough subject so I can understand it I really appreciate it.
Hi Connor. When this was made, 12-3 was a round cable and 12-2 was flat. I'm sure if found a newer version it would show a larger diameter, based on 12-3 being flat once again.
Ok finally got it, the diameter would’ve been wider if 12-3 was flat because the extra wire would have been placed beside the others. But seeing how it is round they are stacked more like two on top of the other making the diameter not as wide. It took me a second, cause I couldn’t figure why there is more wires but less diameter but now I do. Thank you Ryan
Actually subject to local electrical jurisdiction, that supercedes the NEC. And the reason you don't use pvc electrical pipe exposed is because if it catches on fire, it becomes toxic. You should never used pvc exposed, it can terminate underneath switchgear where it is totally enclosed.
352.10(F)
Ok but now about wire current reduction with more than 3 current carrying conductors in a raceway?
You have to address that, for sure, although the exception to 310.15(A)(2) [310.14 in 2020] will often get you out of it.
This guy is the real MVP!
The conduit has too many current carrying conductors also, that is another issue correct ?
Yes. You can use the 90 degree C column of Table 310.16 for ampacity correction, but if you have more than nine current carrying conductors it is going to be a problem. HOWEVER, we can also use 310.14(A)(2)'s Exception [310.15(A)(2) in older books] and make the issue go away completely.
@@RyanJacksonElectrical I thought there was also an exception for that for a nipple (under 24"), and as long as at least one of the ends were open. The idea being that a nipple with at least one open end will not build up a big bunch of heat. The end of the nipple outside of the enclosure still has to be sealed, like in this example video.
Is it against the electricians code of conduct to say you are a better teacher than Mike Holt?
"Probably should have been in the code for 100 years because that is how long we have been doing it." - This made me laugh because it is very true.
In the video you mentioned a connector listed for multiple cables. Can you provide a manufacturer or PM me? @Kevin Muller. Thanks Bud
What about derating than 3 current caring conductor I got nail by using the table but then not derating as well does
Use the exception to 310.15(A)(2) to get out of it.
Ryan Jackson I had 48 12 thhn in a 2 1/2 pvc they made me remove them down to 20 wires and increase the size to 10 which I argued that was would stop someone from then installing 30 amp breakers on those circuits your opinion would be very welcomed
Yeah, the exception I posted woukd get you out of it.
As far as changing the breakers, that is true anytime we increase for voltage drop too. We can't possibly make rules based on people changing the rating of an overcurrent device.
Ryan Jackson thank you
@@RyanJacksonElectrical we can also label/note on the wires on the inside as well as the outside of the panel why the wires are oversized and not to increase the breaker size. Even if there was something in the code stressing something like this,, we all know the trunk slammers and weekend warriors go by"it works, it must be right" thought.
Collectively an amendment to the NEC for a change listing that issue can be submitted as well.
28,000 views over a years time and only 2 people mention the blatantly obvious miscalculations. Yet so many give thanks and congratulate his good work. Not to say his explanation is not well put together or his formulas are not sound. Just he made a simple human error when plugging his values into the equations.
Maybe only two people mentioned it because it was inconsequential?
Your calculations are wrong....
Your initial wire count was (11) 14-2 and (7) 12-2. How ever when calculating your area you calculated for (11) 12-2 and (7) 14-2
Good except areas are expressed in SQUARE inches, and volumes are expressed in CUBIC inches…not just “Inches”. 2.58” is a linear quantity not an area, or a volume. I know what you were saying but I guarantee there were a bunch of watchers of this who were confused. Those code sections deal with AREA… square inches. So say that.
Why anyone would ever try this install in the first place is beyond me.
So many stupid nec rules....as usual
The NEC rules exist to save lives.
@@BattleToads1990 yes, especially considering they are different in all state lol and they are made by people that have never worked a minute in the field
The only difference state to state is which version NEC is currently adopted. Its still the NEC, the minimum that we follow that comes with doing electrical work safely, consistently. There's no whining in electrical work either, do it right or don't do it at all...
@@NA0533 be sure to pick up a copy of the NEC. You will find a form that in the back that you can submit any changes or additions to the code. Most people on the code panels started out in the field and worked there way onto one of the commitees. Like everything else, you can be part of a change if you want to!
@@JM-iz3fr I was talking about state amendments that make changes to NEC. Many items including raceway fills are different from NEC
All your free videos are fun to watch.