Finding a bad neutral on a Service - Raw footage
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- Опубликовано: 29 сен 2024
- Hey all!
I wanted to show a couple shots of this job because we receive flickering light calls quite often. There can be dozens of reasons as to why the lights are flickering but there are two main categories:
- Loose "hot" connection.
or
- Bad neutral.
It's important to figure out what exactly you're looking for first. A bad neutral can harm customer equipment, so it's important to rectify that problem before leaving.
A bad/loose hot connection - voltage will always go down. If voltage goes up on one side, you have a bad neutral. it's literally as simple as that.
That being said, there are the occasional transformer or tap changer problems that can result in high voltage.. If that's the case the voltage will be consistently high as opposed to high/normal as load is removed.
I just grabbed this footage quick, as usually the customer is hanging around a lot more when I respond to these calls (Inappropriate for filming). Today, the customer left for a dinner so I figured I grab a couple quick shots. I apologize for the bad camera angles on this one :(... I literally just took my phone out without any planning or lighting.
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You did it the hard way. You could have measured the voltage on each side of the junction. Should have been basically 0V. You had 3V there.
Yes and no. The initial test of the meter socket determines what exactly I'm looking for... A bad neutral or a loose connection, maybe even a bad tap clamp.
Once you've determined that there's a bad neutral you could definitely move forward by checking across each neutral connection for a voltage drop.
The only other problem with that method is; if you've missed a connection or somehow skipped one you won't realize it. When using voltage on each leg if you suddenly start seeing good voltage you will know you have gone too far down the line.
The way the test was done was the fastest way to find the open . once you find the open point you cam measure across that crimp. you keep going to the source of power until you get normal voltage. it is much quicker that way. this way you do not have to test every crimp for voltage drop.
Yes, this method allows bisection. Divide the line into segments until you find the fault.
Not a lineman, but wouldn't something like a thermal camera have shown this immediately? A drop of 4V with 1A going through that crimp means 4W- so heat is being generated.
@@MattAtHazmat 4W is a very, very small amount of heat in a large piece of aluminium wire open to air. It's not likely to show up well.
Hey all!
I wanted to show a couple shots of this job because we receive flickering light calls quite often. There can be dozens of reasons as to why the lights are flickering but there are two main categories:
- Loose "hot" connection.
or
- Bad neutral.
It's important to figure out what exactly you're looking for first. A bad neutral can harm customer equipment, so it's important to rectify that problem before leaving.
A bad/loose hot connection - voltage will always go down. If voltage goes up on one side, you have a bad neutral. it's literally as simple as that.
That being said, there are the occasional transformer or tap changer problems that can result in high voltage.. If that's the case the voltage will be consistently high as opposed to high/normal as load is removed.
** I should have also show in that last clip, that if you check voltage across a bad connection you will see that 4/5 volt drop.
Super helpful thank you
Great video I was working ina foreclosure house some lights were very bright I tried using an air compressor it would only buzz. I measured two outlets one had180 the other had only 60 volts great job explaining what happened
I see that a lot in automotive or HVAC work. Checking the voltage drop to find the resistance, aka the bad connection.
why does the voltage go up?
should show what house lights look like in a call like this so the rest of us know what to look for before calling the power company
Had a bad neutral in my six unit townhome building a few years back. I watched a number of videos trying to understand how to locate the fault but never found as clear of an explanation and demo as this one. Thanks Aaron!
I called the power company who claimed they came out and checked the pad mount and didn't find a problem (I work from home and *never* saw a utility truck show)... Then called the HOA who called out the electrician. Never learned where the fault was, but I'm guessing it must have been the building main disconnect.
I agree with thephantom1492. Test each hot leg to ground. If you get an imbalance put jumpers in the channel and read across the neutral connection in the channel. If that connection is bad you will read the imbalance voltage. If it reads zero do the same thing at the weatherhead. If it reads zero there now you have to go to the pole. Where ever you read voltage across the neutral connection that is your bad connection. If there is an inline splice half way between the house and the pole which is not a normal electrical splice that also could be where the problem is. Most of the time this kind of problem will cause dim and bright lights. I've seen it high enough on the high side to do damage to electronic equipment.
I learned something today! Thanks, Bob!
Nice explanation. Thanks for sharing your knowledge
IMHO, if you're going to try to test by turning on an unbalanced load, what you should do is actually _turn off all breakers_ except for the one going to the microwave (or whatever), then turn it on. That way, if the other side goes up dramatically in voltage due to a bad neutral, there's nothing actually connected to that side which could end up being damaged in the process.
@eDoc2020 Keeping track of the circuit's paths is an indicator of ones troubleshooting skills. I always endeavored to know the circuits under test. Like computers, the brain suffers the same issues of "garbage in = garbage out" syndrome. If you do not know the actual circuit, your techniques may seem irrational.
Informative, good video !
This must be a real PITA for buried wires.
you check the same way... at each end, then call the underground crew if it's in the middle.
I had this problem about 2 months ago, It took me more than 10 phone calls within the 3 weeks period and finally a random day the lineman show up to fix the problem. btw I am in Chicagoland area the most corrupted city in the US.
When you start at the customer's meter and search back towards the transformer for the bad neutral, can the bad neutral be past the transformer even a half mile away?
Typically the problem will only go as far back as the transformer
Does the neutral come from the transformer or the electric company? I only have 2 wires coming from the electric company to the transformer, one wire is at the top of pole and other wire about 3 ft lower.@@Bobsdecline
I think I finally found my bad neutral, got tired of sitting in the dark and eating sardines out of the can, so like you said search back towards the transformer, is I put my latter up on the transformer pole I do tree work so the height doesn't bother me, and I see fire crackling in the neutral lug on the transformer when I wiggle the neutral wire, so I was wondering why I am see fire crackling, could it be charged.?
I finally found it, it was where it bolted to the transformer, thanks for all your help.
I have been having problems for a couple of weeks things are normal at other times I can turn a lamp on and my box fan doubles in speed and other times it slows down when I turn on the lamp. Could that be a bad neutral?
It could be... If you have a multimeter/volt meter, you can stick the prongs in the socket and check the voltage. While monitoring the voltage, try turning some random items on/off. 120v items like toaster, microwave, coffee maker especially. If you have a bad neutral, you should see a fairly drastic increase or decrease in voltage.
@@Bobsdecline Thanks so much, I will try to find a deal on a meter and give it a try.
If it does show a bad neutral, I'd definitely recommend hiring a professional to investigate further.
I work at a LU and lineman always says never disconnect the neutral by itself (leaving both hots connected) because there would be no return path and would damage electronics also
When disconnecting at a transformer if a meter still plugged in .one of the hot lead would be energized ? Can someone explain
Using the scenario in this video; The neutral, although bad, was still carrying some current. If it was completely cut off the voltage fluctuation would be much more drastic. Cutting a neutral clear off is a good way to send 150+ voltage through half the customers home.
For the second question (a disconnected hot lead being energized) it's pretty simple. Power can flow from the remaining leg, through any 240v loads in the house (or even the meter's own internal circuitry) and back on the disconnected leg.
Do you work for nspi
I learned about a loose neutral at a house I once owned. Every time I turned on a toaster the kitchen lights got brighter. I went to an electrical self help blog and a user said it was most likely a loose neutral. In the main panel I found the previous owner/builder had cut the neutral too short, bent the conductor to a 90 degree angle to get it into the lug, then failed to torque it properly. The aluminum wire had heated and corroded over time. I repaired it and the problem went away.
Love the troubleshooting very interesting to watch for me being a HVAC tech. I deal with lots of electrical troubleshooting so very interesting seeing others doing a different job doing other types of electrical troubleshooting.
When the power goes out at night and we're all just sitting around thinking, 'somebody's working on it right now.', - this is the guy! Bravo Bob!
The problem with turning appliances and other loads on u can burn appliances and other equipment up
Absolutely. Typically, the problem has been on going for a day or two before it gets to the point that we're called. It's kind of one of those "the damage has already been done" scenarios. Using a slight off balance (under 130v) to help trouble shoot won't hurt anything for that short period of time.... Voltages any higher, just pull the meter and try and find it visually. Pretty much change anything that looks bad at all. Once done re-check voltage and hope it's good. Definitely have to confirm voltage before leaving.
Most utilities have a device called a super beast that plugs right into the meter socket, which simulates the load you would get from a hair dryer or a microwave. Quickly tells us if it's the customer's problem or an issue with our stuff, without risking damaging the customers equipment.
I work at the local telco, and I probably run about 10-20 calls a year due to a BROKEN neutral line causing our coax service line to melt at our tap or at the ground block, since we bond to the ground. I'll inform the customer to call into the power company right away. I normally can spot the break! Now you have me thinking of what issues a bad neutral can cause for our internet customers. Have you ever seen this issue (melted coax) yourself?
Another comment literally just landed at the exact same time as yours, describing exactly this!
Next time I come across it, I will definitely document it.
It can be very dangerous and difficult to detect and understand what exactly is happening.
But yeah... That coax or telephone drop (next) carrier can definitely attempt to BECOME the neutral 😧
That was probably me! Unlike most techs, it really piqued my interest, so I wanted to figure out why (Yay inquiring minds! I think I have undiagnosed ADHD or autism...and I'm not poking fun at those who have it!)
@@grabasandwich I find this video explains things very well: ruclips.net/video/LJvyb_WujZg/видео.html
Just remember that "the ground" has really nothing to do with this problem, because the voltages are not high enough to actually push much current through the earth. But anything grounded can try to become a path for the neutral back to the transformer.
@@jovetj yeah, I've seen that one! I wish I was good at making videos like these guys!
A long time ago, early 1990's, living with my parents, every so often the lights would go brighter or dimmer. Sometimes they would get so bright the 100 watt incandescent lightbulbs would POP and I would have to use a potato to get it out. JUST KIDDING! I turned the power OFF and took it out safely. Often, our floor model TV's built in circuit breaker would trip.
When I took transformer power transmission theory and they taught us what happens when a neutral is loose I realized what was happening.
One night it happened and my bedroom light became REALLY BRIGHT.
I grabbed my Fluke 73 True RMS multimeter and checked the voltage from neutral to line at my receptacle and I measured 194 VOLTS!!! 😮 That only leaves 46 Vac on the other line! THAT'S a serious imbalance. Looking back on it now I'm amazed that only the odd light burned out. Today's CHEAP electronic crap wouldn't stand up to that kind of abuse.
I went to the basement and checked the breaker panel for heat and it was so HOT I couldn't touch it for more than a fraction of a second. I took the cover off and found the main neutral connection was loose. I tightened it up and never had that problem again. That burned into my mind just how dangerous a loose neutral or disconnecting a neutral that is BEING USED can be!
As a non-lineman homeowner my only experience with this was years ago when my lights suddenly got real bright when it was windy then returned to normal. Got out my meter next time it happened and I was getting 188 volts on that circuit. Don't remember what the other leg was, but it was quite low. Had to head to work, and didn't know what was causing it so turned off all breakers except my fridge before leaving. When I returned in the evening I saw that my neighbors line (triplex) was brand new. Haven't had that issue since.
We had this exact problem like 25 years ago in an old house my parents had. The neutral connection had basically rotted right off on the house side of the service drop. It was an old house so everyone assumed it was faulty wiring inside the house and wasted a day or two going through all the wiring in the house. In that time we lost a few appliances, electronic devices, etc. before one of us happened to look up at the service and see the neutral wire either wasn't attached or was barely hanging on. (I was young then so I cant remember exactly now.) Power company came out and re did the service connections and everything was fine after that.
Great video as usual!
If the neutral was grounded to a water pipe in your house and also another adjacent house, the unbalanced load would have 'found its way' back to the transformer through the common water pipe. This is why smart people are careful with their ground lug lifting and reconnecting. You may find 120 volts between the lifted ground wire and the lug and if the pipe is wet you can get quite a shock.
@@rickhawkins218 I was maybe 10-12 years old when all this went on so I'm probably leaving out some details. but like I said it was an old house (150~ years old) with old wiring lol not knob and tube old but it was still an old system.
The house changed hands a few times after we left and was eventually torn down about 5~ years ago and a new building was constructed.
If that old house was on a well instead of city water, the ground wouldn’t make it to the next house.
You should be able to measure that ~4-volt difference across the bad connection on the neutral. That's an easy way to confirm a poor connection.
Definitely another easy way to check!
I should add, still requires the same off balance load.
@@Bobsdecline what, you don't carry one of those load testers that plugs into the meter socket? Hmmm, maybe when Milwaukee makes one?
You can also just check for that resistance with the load isolated. Especially if you have a meter with a proper high current continuity range, which will let you read down into the low tens of milliohms. Not sure how readily available those are in NA.
Really good description of the problem and diagnosis! Did you have to cut power to the home in order to change the neutral clamp? (I assume yes)
If he did a disconnect on the neutral to clean and install a new crimp, the voltage would have gone nuts / imbalanced while he was working. Always do repairs without a load.
Yessir 🙌 Thanks guys! And great answer as always Rupert!
Doh! I was about to say: "Sure: but put a conductor strap between the supply and service sides of the N during the repair." Not sure how feasible this is or if it's agains the co. rules.
@@AlanTheBeast100 Job only takes a minute or two. Just kill the power.
I'd be worried about placing a large enough load on it to raise voltage to 150 volts, that sounds like enough to risk damage to devices or appliances in the house. (maybe enough to trip some sensitive surge suppressors?) And there are probably a few items here and there that could be damaged by applying too little voltage as well.
I answered this in more depth on another thread... But basically it's already been going on for days and the damage has been done. Voltage has to be checked to confirm. As you as you see those extreme voltages. Pull the meter! Don't use those voltages to help trouble shoot.
Voltage must then be re-checked before leaving...
This is amazing. My energy monitor claims to be able to detect this and I've always wondered how. Thanks for this amazing video
For anyone still confused why this happens, normally the neutral is referenced to ground, by being connected to it. So the neutral is the 0 volt point that the +120 and -120 are measured from. If the neutral isn't making a good connection it will be pulled above or below ground by the leg that has more load. The bad connection is basically moving the 0 point in relation to the 2 legs. That's also why the 240 isn't affected, they're still the same relative to one another. That's kind of an oversimplification, but its more or less how it works.
This explanation works perfect with a vector diagram of a three phase setup with a floating neutral too.
Keep in mind that the neutral being grounded has nothing to do with this circuit. The neutral is the center-tap of the transformer's secondary winding, which splits the 240V of the full winding into two halves. The neutral back to the transformer normally only carries the imbalance of the two 120V legs anyways. Whether it is grounded, or not, changes nothing.
I had this lesson early in my sound-guy career. I plugged-in a sweet small PA system on a familiar campus. It sounded extra good! For 15 minutes, and then FWOOMP! Mushroom cloud to the ceiling. I fetched my meter: 160V, where we always had 117V. I asked in the office if they were having power trouble and she said no, but the MrCoffee was taking forever to get hot. That outlet was down below 80V (it was a Line Meter not made to show small volts). Ceiling lights steady, musta been a different circuit. Already I had a glimmer but the campus electrician came right over (the FWOOMP! scared people) and explained in detail. A Neutral wire had come right off (low-bid contract). My 30W PA and the 1500W MrCoffee were splitting the 208V, UN-equally. (It was a 3-phase job so there is a root-3 in there, but whatever.)
The smoke was a main filter capacitor the size of a soup can. Over-volt it a while and the guts boil out. What a mess inside!
@@jovetjThat is incorrect. By not grounding the tap it is not neutral. If not grounded you have 3 hot legs on a single phase tapped transformer. You would still get 120/240 from leg to leg or leg to center. If not grounded though depending on loads your voltage from l1 to ground and l2 to ground will not be 120 it will acually flucuate hope that helps
@@1xXCoLeXx1MC But it is neutral...it's in the middle between the two other legs. You're correct, if not grounded it's a "hot" one, but it's still neutral. Same applies to Y 3ɸ.
Do you guys perfer to have electricans always look on the other side first? I am fairly certain I have a bad netural but dont know if I should call an electrician first or the power company.
We definitely prefer an electrician checks it out first...but that can also be costly for you. Some cases the power company will not come out until and electrician has checked things out first. It's about 50/50 that the problem is on our side vs customer side. If you have an older home/panel... It might be worth having an electric loan come by anyhow to check things over.
Power company is free. Call them first.
I had a failing neutral but it was on my side. Electrician came out, and recommended changing out the neutral, as well as the meter base, panel, and leads from the mast head down. Reason for replacement of meter base and panel was extreme corrosion on the neutral lugs. My home is 35 years old.
After the work was done, problem was resolved. Emergency repair bill in Newfoundland, Canada April 2024 was $8k
While the electrician was writing up the quote, he notice the lights dimming, so he put a volt meter on both hot lines in the panel. With only baseboard heaters and lights providing load, he saw a voltage difference between 100-150 volts. He immediately ordered emergency power shutoff, and work was completed the next day.
2 weeks before calling in the electrician, turning on the dryer almost caused an electrical fire on a power strip with only a Roger’s modem plugged in. At the time, I thought it was just an old power strip that failed.
2 weeks later, turning on the microwave caused lights to blow, then lights started flickering, TV shut off, and modem keep restarting.
$8k was a huge unexpected expense, in an emergency situation. That includes an upgrade to add a surge protector at the panel, so I could have saved a few hundred dollars by not doing that upgrade. This work was to replace the existing 150 amp panel. If I wanted to upgrade to a 200 amp panel, the bill would have been over $10k. I almost fainted. lol.
I still have 20-30 amps reserve in the panel if I ever need to do any additions, like a mini split. So there was no real need to spend an extra 2-3k.
Probably could have got it cheaper by shopping around, but in an emergency situation with a reputable company with availability next day, I just went with it. Electrician did a clean install and government inspectors approved the work. Ed Budgell at Mr. Electric in St. John’s did the work. Super nice guy, answered all my questions, explained everything, and was very humble. He takes pride in his work, and wants it to look good too
I've been chasing some odd power issues at my place for a few years. I redid the breaker panel to balance the legs better and that helped a lot, but thinking back, I think one leg was going up when the other went down. Maybe it's been a bad neutral all this time. I'll have to check next time I'm back home. Never knew you could check for a bad neutral like this, but it totally makes sense why that would work.
If your lights are flickering intermittently (or like others have said, some going bright) I'd get that looked at ASAP! Could be a serious fire hazard. Good luck!
when there's a bad neutral, I generally find the CATV coax carrying current back to the street(scary!), especially when you find it's smoking hot, melting and carrying over 15amps of current.
always clamp on ammeter test! don't go playing and handling it directly unless your geared up.
I've also found current flowing back out city water supply lines via the ground bonding to older metal service lines.
some buildings with the neutral completely ripped off and still working seemingly perfect, no signs of problems, stable voltages and nobody had a clue. other than I've started to check the alternate grounding paths by default.
We have a tool called The SuperBeast that finds open neutrals….it takes the place of the meter and puts a load on the service….….It’s a troubleman’s best friend and it narrows down if its a customer problem or a utility probem….
That neutral is wanting to take a long vacation from delivery of the proper voltage to the customer 😡😡
Would a DIY homeowner see this voltage difference across the legs of their dryer or stove outlet? Or at the fuse panel. The same as you showed at the meter? Most power companies frown on people removing their meters, of course.
Yes, and if you remove a "smart" meter, the power company will be immediately notified.
You can check safely at an electrical outlet if the user is competent in doing so. From that test point, the problem could be anywhere from the outlet itself, to the breaker/panel and right out onto our system.
This is a Job you want to make sure your Head is in the Game at ALL Times. Thanks for doing a Consistently Solid Job. 👍🙏
I wonder if it would be possible to have a test apparatus that plugs into the meter socket that allows applying a loads without energizing the customer equipment, with voltage and current measurement points. Take the guesswork out and prevent a bad case like this one from doing more damage.
The st800 or beast puts artificial load on the conductors.
Once my service totally lost the neutral, that can be very destructive to some of the 120v devices as the voltage can swing very unbalanced line to neutral depending on the running line to neutral devices. Thanks for the video and explanation.
Nice video Aaron. Sometimes you can use a voltmeter across both sides of a splice connector and see the voltage difference. In your case it might have been anywhere from 1-10 volts. This can also work for a Main breaker or individual SP or DP or Three phase circuit breaker and fuses too. Stay safe!
Wish you worked for my provider. Had the same issue intermittently lights would get super bright for a moment then dim. Guy came out around lunchtime and said bad neutral no biggie which I knew was the usual suspect. Guy went to the pole and found what he visually suspected was a bad crimp. Changed it out and assumed it was good, didnt even say anything to us after, he just punched the meter back in and split.
Problems came back quickly and it was getting worse so we called again and they sent the guy back out, now just after dinner. Finally put a meter on it and had 142 on one side and 109 on the other with power on. Decided it had to be at the service connection on the house, but now it was dark so he couldnt use a ladder without calling someone else because of the SOPs. Told us he wouldnt call cause the company doesnt like to pay a second guy OT. Say he can leave it or he can back across our lawn and use the bucket, but we have to sign a release for any damages that did to our lawn. Im a firefighter, and the thought of 142 volts with an older home and some things ive found from past DIwhy owners- and what i havent found and wasnt going to have it left that way.
I did protest some and point out that he could have fixed it the first time and therefore asking for a second person or not asking us to sign a waiver wasnt unreasonable considering it was a safety issue and it was his second attempt. His response was to threaten to cut all power and come back tomorrow as a 'screw you', which he may have done had I not pointed out that we were standing in front of my ring doorbell and that as bad as all that would already look, and as much as I despise people who use it, there's law about cutting power when there's a disabled child that he would be violating.
Amazing how fast he reacted to the realization he had admitted on video that he had made an assumption, not tested anything before or after and then found that he left an unsafe condition which he refused to ask for a second tech or not drive a line truck across my lawn to fix then topped it with a threat to cut my power and have no heat or water if I didnt let him tear up my yard to save himself getting chewed out by his super for needing the second guy... A second guy was rolling up 5 minutes after he called dispatch...
Have had 2 TVs die and the power supply caps on the main board on a fridge burn out soon after...but im sure its pure coincidence...
The situation with sop's is somewhat reasonable except for one major problem! (As you pointed out). He was already there earlier and messed up! Him/the company should have been rolling out the red carpet at that point!!
Also imo, a bad neutral on company side, should have been fixed regardless of o.t costs.
@@Bobsdecline agreed on all counts... but I think he knew if he had to call then he couldn't avoid telling his super that he screwed up. If he pressured us into the waiver then he could fix the second issue and nobody would know that he screwed up.
It's always nice to see voltage drop testing done in a completely different context. Ultimately it's the same lesson, don't expect to see much unless you get electrons moving.
This is a GREAT video that shows the electrical theory of why the neutral is important to 120V circuits in a home: ruclips.net/video/LJvyb_WujZg/видео.html
Yeah it's no wonder it has 750k views! I wish I made good content like these guys so I could make a little supplemental income 😊
I'm an engineer who has worked on industrial projects my whole career. I pays to have electricians who understand wiring in an industrial facility. On my very first project a bottling/canning plant for Ocean Spray, yes I was very green, we had electricians who had only performed residential work wire the plant. Oh my. Hot neutrals all over the place. As in 480VAC hot. They couldn't read the drawings. It was that simple. And the drawings were just fine. I got the job of fixing all of their mistakes on the automation end of things. Really surprised nobody was hurt.
If you lose your neutral all together then things go from bad to worse real quick.
I've seen around 220Vac on one leg before which means everything not being protected behind a surge protector gets destroyed instantly 🤢
It all depends on how the 120Vac legs are loaded because with the Neutral (transformer center-tap) disconnected the circuit becomes a voltage-divider hence the voltage across each leg is based solely on the resistive loads. Unless the loads on each 120Vac legs are balance then you'll have more voltage on one 120Vac leg compared to the other.
I've seen linemen remove the service meter and plug a device into the meter base to simulate an unbalanced load to find the problem so there is no need to bother the customer with turning on appliances.
Just wondering if it was re-crimped with "anti-oxidant joint compound" to prevent the cable from oxidizing again due to heat which is why that connection was failing to begin with.
It's not rocket science 😊
Checkout "Open Neutral" on Dave Gordon's channel which perfectly illustrates this problem 😉
By the way, this is exactly how to check for bad wire or connections on a 12-24Vdc system using the "LoadPro" probe. Open voltage won't show the problem until you put a load across it then the voltage drop becomes obvious 🤠
That happened to me and my neighbor in 2005, power company transformer lost its neutral connection to the distribution neutral ,both legs went wild ! Power company bought us new televisions and microwaves .
I saw this when it was '7 minutes ago' and it already had 140 views. That's a view every 3 seconds!
I have a long thin Neutral. The less-load side WILL go up, but less than the load side sags. Work it out on paper, or with resistors and two batteries. You observed 4V+4V or 8V at about 1A unbalance. There's 8 Ohms in that Neutral. My house will show 0.2 Ohms in the Neutral (500'+ #2 Al). The microwave causes 4V drop in one leg and 1-2V rise in the other leg, tolerable. (The place was wired for a trailer, this house just happened.) Your 8 Ohms is certainly too much.
Now 1,000 views in 47 minutes, more than every 4 seconds. (Had a dog walk in the middle.)
Lol glad the dog had a good walk 😄. That's an interesting scenario you described... It's basically not preforming %100 as it should with today's standards, but like you said - still acceptable and not really anything wrong! Those ones are tricky to come across and always want to double check that everything is ok.
Remember that, under normal circumstances, the neutral from the main disconnect back to the transformer only carries the imbalance difference of the two 120V legs. If the loads on both legs are perfectly balanced, the neutral will carry zero current. But, that situation is really hard to actually find.
@@Bobsdecline " not performing %100 as it should..... double check that everything is ok." The so-called Home Inspector, when we bought, was clearly confused about almost everything. The 115V submersible well-pump IS unusual, and does dim the lights. (CFL/LED are self-regulation and much better about that). But a 230V pump won't pump at 120V, and the catalog we found in the house shows a 115V pump as the lowest model.
There's always losses. 2% to 10% at full load is reasonable. Less than 2% at rated load, a short would be dangerous. 10% loss at nominal 100Amps makes my 125V at street into 112V in house, and most stuff is fine (even the PC does not burp). The oven has to pre-heat a little longer, the water heater is a little slower than rating, fine. And we never get near 100A even laudry day.
I did take it seriously looking for hot joints or baked breakers. And cuz the fusebox was a mess I added a box at the meter and a new box down cellar. And did find screws never tightened right. But the long feeder-drop figures to be my sag, almost exactly.
@jovetj My 120V loads are never perfectly balanced, but it is interesting that they are never very far off-balance (except the 44A start-surge on the 115V pump). I didn't obsess about balance when I wired the new box.
The voltage drop in this video is actually only 4 volts, you don't count it twice. Other than that you're definitely right.
This situation is all to common in old services in the USA.
So the Neutral joint was high resistance then?
In short, yes
@@Bobsdecline Great learning video 🙃
if you are half empty glass kind of a person, then it was low conductance joint ;p
Lol
@@griffon2-6 Like it
I received a call out to a residence that recently had a new service pole and pole light from the supplier…flickering occasionally…went thru the typical checks, loose something here or there, finally got suspicious and went to the service disconnect…incoming lines were 150 something and 80 something as I recall…wowzer! quick call to the service center and had them out shortly after…the pole well off the road had the transformer mounted and it was their baby from there…they had to cut trees, all sorts of bs to get to it….they never indicated what exactly was the culprit..I suspect it was from the transformer to the triplex..as they needed to head back for wire…
The voltage difference wasn't as drastic as your explanation. 5 or 6 volts is enough of a red flag?
Absolutely. The customer shut most everything off once arrived. The symptoms they described were much worse than what we see in the video. I didn't want to unnecessarily expose their system to those extreme voltages.
Yes. It still shows that the neutral connection has a bad connection. Like Aaron explained, the load was small and almost balanced. Higher overall load or a greater imbalance will read a higher voltage difference.
@@mxslick50 using a resistance heater or toaster on one leg (10 - 15 amps) will dramatically increase the difference between the leg voltage and spikes generally won't bother them. That 4-5 amps showing in the video isn't really enough, unless you know where to look. The power company has a tester that plugs into the meter socket to do exactly that. It's basically 2 hair drier elements and a fan. You can run one or both for testing. Some have volt meters built in as well.
@@rupe53 Thanks, I am aware of that already. The tester you refer to is called The Beast or Super Beast, my old local utility used them. I've been an electrician for over 40 years now, and have used the toaster trick to help diagnose a bad neutral.
@@mxslick50 never heard that name in my neck of the woods. Since I retired a few years ago, I will probably never have to deal with it again either. Still in all, good stuff to know... and pass on to the younger guys.
When the current is really low like in this case, it probably doesn't take much difference to cause a noticeable voltage difference. If the house had been drawing 30A + 32A the voltage difference might have been in the noise. All due to the winding resistance at the Xformer.
I like trouble shooting videos. A few months ago one of my UPS' signalled a ground fault. Took me many hours to find it. (Was in a ceiling light box at the other end of the house that also fed the bedroom end of the house where my office is). I figure that open ground has been there for many years. Only when I moved the UPS did I see the GF light. Hard to find, but easy fix.
Great Work!!
-Master Electrician (inside wireman) from Wisconsin
Ohms law!
The first house I owned had a bad neutral. Back in the days of incandescent bulbs, when the motor in the dishwasher started, a nearby lamp got brighter. Now, the challenge was getting the utility to make a visit. No one had lived in the house before i bought it, it had been the office for a few model homes. The neutral to water meter seemed OK, as did the neutral inside the meter pedestal, which i could open about an inch without breaking the seal.
I called ComEd to report the problem, and of course, they wanted me to call an electrician first. I exaggerated my credentials, and told them i was an electrical engineer, while I had only taken a few Electrical Engineering courses as part of my Computer Engineering degree. This was enough for the person taking the call to dispatch someone. When i got home from work, there were no more lights getting bright as I ran the dishwasher.
I know the utility wants to be sure the problem isn't on the customer side before dispatching someone, but that would have cost me real money. I did as much debugging as i could without pulling the meter.
We use the super beast tester
Best way to test. It took us forever to finally get them.
That's certainly ideal!
A loading meter (Lo-Z) might have found the problem without having to turn on loads inside the residence
Yes and no. There was still a few ohms across the bad connection so the few thousand ohms of a Lo-Z meter would not do much. You'd need a specialized test device which does exist.
How did the voltage jump up from Service side of 123 volts to 128 volts on the customer service side, by simply passing thru a splice ?
🤔....?
It's because the reference point is not transformer ground. Relative to transformer ground the no-load voltage on all three wires was 123-0-123, under load it was 123-5-123. The voltage comes from the other phase drawing more current and causing voltage drop.
I hate neutral problems... Thanks for the troubleshooting vid... I check up to the meter and then call the line guys...learn something on all your videos... Thanks...
This is the clue I was looking for. Now, I know where to check. That voltage imbalance was driving us crazy.
Very Interesting video!! I'm surprised you didn't talk about the customer's ground, (driven or water pipe). With a defective service neutral you will get return voltage on the house ground. (If it's the easiest return path) You could also amp probe the customer's ground.
Keep the videos coming, very enjoyable!
Here i lost about 10k worth of equipment and time at least due to a lost neutral. It took EIGHT months for the power company to go up on the pole and replace a 4 ft piece of wire from transformer bank neutral lug to the neutral wire on the pole.
All this started with hurricane Zeta around a Halloween ie end on October..
The only reason the power company camenin June was their system on a windy day had my TWO service entrance smart meters freaking out with the lost neutral
The green new guy was disappointed that the meters looked ok and two service heads and secondary wires to the transformers..
Only the old guy would listen. I told he he had a loose neutral at the pole.
The guy balked at even checking it.
So i asked the guy what are the odds your stance is correct that both meter curcuits magically loose the neutral exactly the same time on a windy day?
So i showed the old guy two sets of 4 bulb neutral testers on my 2 meters circuits
2 pairs bulbs in series across 240 volts. One set has a connection to the neutral. The set connected to the neutral has a super bright bulb and super dim bulb on windy days.
All 8 bulbs can be seen at a central place in my building.
During a loose neutral event both service entrance meter circuits have the bulbs going bright and dim exactly the same time.
So this sank the local power companies stance that it is wiring problem in my building
Both power company guys actually told me i need an electrician. As a registered engineer in EE i told them the were wrong and one of you need to go inspect the poles neutral to transformer connections.
So the older guy went on on the bucket and touched the neutral wire with a pole and saw sparks.
So he came down and said i was right. He installed crimped a new wire from transformer to neutral wire that is on the poles and problem went away.
The power company came out orginally after i complained after zeta. The arrived with a super brute and declared not their problem. It has to be my wiring.
They came out on a still day. So their neutral load tester did not have show bad with an intermittent connection
After that 1st test by a super brute a vile lady in customer service barked that they already have been there and not their problem
So because the power co did not know what they were doing i had to buy several dry 0.5 to 2 kva 240 to 120 step down transformers.
Ie act like 3rd world stuff. Run computers credit card machines. Ups. Printers. Phones any critical 120 volt stuff on my step down transformers.
That way the 120 volt stuff is not effected by a loose neutral.
The local power co had many lawsuits due to zeta. That is why the vile customer service lady barked it is your problem not ours
When Disney on ice travels they use stepdown transformers since they have had show equipment all blown due to a lost neutral
Lost about 20 plus surge protector plug strips due to that lost neutral after Zeta..
Lost a ups. Two credit card machines. Dozens led bulbs. Computers.
Giant mess
Yikes! that was high resistance. Glad it was found and corrected. What is the process if the bad neutral was feeding multiple homes?
Pretty much same process for trouble shooting. Have to check other meters of course to confirm.
Usually if it's a connection feeding multiple homes, I'll just open the transformer once detected. (Until repairs are completed)
I recall seeing my first bad neutral at a house we managed -- Randomly, appliances in the house would start smoking without being touched. Voltmeter read fine, until I set it to hold on max, and then saw that it was briefly spiking to ~190. Was a windy day by the ocean, and over time the neutral loosed within the meter, most of the time making decent contact except during gusts. Love seeing your step-by step of diagnosing problems!
I'm curious what amount of voltage deviation would be considered normal or acceptable? Like I haven't fully quantified it but I know if there's say 30-50 amps of imbalance current they're becomes a measurable amount of imbalanced voltage...but it doesn't seem significantly different than the amount of sag like when the auxiliary heat kicks on with 60-100 amp 240V draw and the entire house panel voltage dropped by 5V or so
Well I have been trying to find my bad neutral for over a month now, I appreciate you, is there a such thing as a neutral that only acts up every now and again? I check L-1 and L-2 every day at the meter box almost every day it's 122 on both legs I can turn on the space heater it goes 120 on one leg 124 on the other but once in a while it will be 132 on one leg 114 or close on the other.
Assuming you have one on you, would this be a situation where you might be able to use a thermal camera to speed up the process of locating the bad connection?
Sometimes... In this case, I double there was much heat if any at all. I've definitely seen bad neutrals get hot or even have the neutral take another path through a pipe, meter box or bond and glow red hot!
Actually I posted footage of this on my Instagram if ya scroll through to one of the earliest posts
I love it - very well explained - clear and logical. I troubleshoot computer programs, and the thought process is identical, as different as the steps may be.
We use the Super Beast to test our line side neutral(HJ ARNETT SUPER BEAST-D HJA-469-SD SERVICE CONDUCTOR TESTER). You have to disconnect the line side neutral from the meter base socket and hook up the beast. If the beast runs at normal fast speed its usually a sign its good. If it doesnt run at all or very slow the neutral is most likely bad and the tell tale sign of unbalanced load is usually a good indicator as well.
Very interesting. Learn something new today. Electricity is a funny little monster so cute but has a bite. Thanks for explaining how to troubleshoot the issue.
Sounds partially like a problem I have, but then not so much. I have a decent APC model UPS unit. It generally shows 120v. However, when I use my microwave oven on partial power, the UPS beeps and shows over 200 V for a moment, then drops back to ~120V. I can't figure this out! No lights flicker, TV doesn't show any sign of anomaly, nor does anything else. Does anyone have any suggestions as to a possible cause? (I'm in USA)
A 4V drop at ~100A would mean that connector is dissipating 400W. You should be able to feel the heat coming off of it!
GREAT VIDEO!
This is exactly what happened to my house a few years ago. The lineman had me put a bowl of water in my microwave while he took readings. He re terminated the neutral connection at the transformer. No problems after that. It had been like that for a while. The spikes killed one of my UPS's and I had scorch marks on my light switches.
This is one of those uncommon (but not rare) situations that homeowners need to be aware of.
Does your utility use a load tester that plugs into the meter socket? The tester puts a ~20A load selectively on each side of the service while displaying the voltage on both side. I had this exact problem on our service. An unbalanced 20A load would pull the neutral up about 20 volts. The culprit was a corroded connection on the buried service entrance.
Reminds me when my neighbors and I lost one of the hot leads off the transformer. It was happening during the daytime when most people were not home. Because we were the only ones home, we thought it was due to the old wiring of the house.
Yes, go for a microwave NOT a dryer, oven or stove element as they are all 240V load or "balanced loads. As Bob said "Unbalanced or phase to neutral loads." Ungrounded to grounded conductor.
Ground current can also go up. Fun fact - when the neutral is breaks on Triplex, the #6 grounding wire tries to carry the load and will burn vinyl siding.
Not a lineman, just a guy who likes watching your videos. I've seen this happen a few times. I was told bad neutral and the voltage swings were really crazy. 40v on one side and 200v on the other. Some people's stuff was getting really hot and smoking.
An open neutral on the service equals UNKNOWN series/parallel loads on all the 120V lines in your house. There is no way to calculate or determine the destruction if the refrigerator kicks on on a different phase than your delicate electronics. I once did a service call for a lady who lost 2 TV sets, a DVD player and her kids game console for a open neutral. I did not charge her a dime.
Great video. Years ago I lived in the basement suite of a house where the neutral was damaged by corrosion and it blew out all of my electronics. I never understood until now how a bad neutral fried my stuff but if the actual line voltage changes it would definitely cook everything.
All of the incandescent lights in the suite were glowing blood red (low voltage) and there was smoke coming out of my AV gear. Sucked.
Some of it was repaired (not replaced) by the utility but was never quite right ever again.
Call me whatever about this (I'm not lineman trained)--but why is NO-OX or something NOT used in those connections but required in residential panel connections indoors? And why not some sort of sealant around the neutral connections?
This happen to me 4 years ago. Took 4 calls to the electric company. I told them I was seeing 136 volts on one side and 108 volts on the other. They changed the meter and never tightened the screw on the neutral. Melted the screw and the aluminum wire. Amazing people like I had come out never checked it.
40 years ago I was a renter and one evening the lights were glowing very bright and the fridge would run quiter so i check with my meter and saw the voltage fluctuated between 130 and 175 on a receptacle so I called the local power company and they came and cheched and said there was nothing wrong, Two weeks later they had to come work on the transformer during a storm, well after that intervention the voltage was stable at 123.
I had a bad neutral between the transformer in my yard and the meter socket.
The power company showed up in less than an hour.
It took months to get them to show up at my commercial building.
Oh crazy 😧 A suspected bad neutral should always be treated as a "low priority emergency". Basically responded to ASAP as long as there are no large outages, fires or any other safety related calls.
I'm trying to picture this schematically.
So if the neutral is bad, it becomes higher in resistance. With an even load, the resistance on either hot leg is equal to the other, so it reads normal even voltage split. Lower the resistance on a leg by turning on a microwave on that leg, and there is now an uneven split. Since there is now resistance on the neutral back to the source, voltage flows along the other hot back to the source. So am I correct that the hot leg that sees the overvoltage would be the opposite hot leg as the hot leg with the microwave? If damage occurs, would we expect to see it on those circuits?
One leg goes up and the other goes down. (higher load leg goes down) You can read it anywhere in the house but easier at a 240 point because you don't need to run around checking both legs.
Yes exactly!
It might not be a bad idea to explain to casual viewers that you don’t pull meters without local utility permission. I’m a licensed general electrician and I do occasionally pull meters- but always get permission from AHJ first.
They have a tendency to get a little crabby if you make that decision unilaterally 😅
Do you have a video or could you do one on phase balancing, my lhase supply (direct 3 phase TT from transformer) is imbalanced and my neighbourhood suffers regular blackouts, i am worried we have too many people on one phase any suggestions what to do and what to ask from our supplier?
A bad neutral cost me over $500 due to smart switches, fridge circuit, and kitchen appliances.
A great example of Kirchhoff’s law. I learned about it the hard way when the neutral in my generator inlet box became disconnected. Fried a few LED lights when I switched on an unbalanced load.
Does voltage drop across the wire work on AC systems? We use this on DC such as starter circuits. To check the ground we connect volt meter to bat ground and the other to the starter. If the meter shows voltage above about 1/2 volt when starter is energized it means too much resistance. Just curious if this would indicate the same thing on AC systems?
I would not use the unknown customer loads to test for a loose neutral. Aside from putting their equipment at risk, you do not know how much load is actually on the neutral. Connect a known load across one line and neutral, and by measuring the line to line voltage with and without load, and the line to neutral voltage with load, you can quantify the relative resistance of the neutral conductor to the line resistance. Switch the load to the other line, then you can also determine the relative resistance of the lines themselves.
i wish this guy had a playlist of the videos based off of the work where we hear a 60/50 hz hum:(
Surprised you didn’t measure across the crimp connector to show the voltage drop across it!
Great and very thorough work as always. Don't mind those in the comment section critiquing you for being thorough.
Bob, 3V on 1A load is a SERIOUS ohmic resistive loss at the bad contact crimp!! about 1/3 ohm.. which mean for each 10A unbalance load there is 30W heat loss . Btw You could also simply measure the low voltage loss each side of the bad crimp.
my line crews carriy the "beast of burden" and they can load test the nuke without putting overvoltage on the house system.
homeowners: if you ever turn on a light and another light gets brighter, that's the warning sign of a bad neutral.
Why are the crimps at the service connections so exposed? Couldn't some kind of grommet filled with grease aid in the degradation of these?
Do you not carry a Beast on your rig? Demonstration of using one would be good content. A load device is far better than relying on the customer loads and potentially causing damage.
Is corosion the cause of the bad connection? Or was it not clamped right from the start?
My lights are flickering in my house and I've gone through and checked with a tester and everything seems to be correct and I'm wondering if it would be correct if there was a bad neutral on the service side or if the tester would show bad inside the house.
5:20 just measure the voltage drop across the crimp!