Troubleshooting ~ elusive neutral ???

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celtic

celtic

Senior Member
Location
NJ
Looking for some tips locating a broken/loose neutral..here's the story:

Customer has an a CCO inspection due for sale of property (multiple code violations). I get 90% of the "tough" jobs done, hit the bathroom to see why the GFCI doesn't trip/reset - 1 old BX in - line/load reversed...simple fix, right? Guess again!

I reverse the wires, put the CB back on...and it hits the fan. Half the apartment is w/o "power" -no lights, no recepts., etc. WTF? :confused:

Ok, I'll just put the wires BACK the way they were...still NFG.
Let the tracing begin...finding buried boxes, dropping fixtures, opening devices & splices, etc. Still no luck...between H/N I have continuity, between H or N I have 110 to G.


The home is probably 60 - 80 years old(I guess?), no K&T BUT the HO's BIL fancied himself as an electrician - you know the type, running BX into plastic boxes, using ANY available circuit for power, etc. This has become, quite literally, a needle in a hay stack - and the cost is rising, something I am not looking forward to (telling the HO the "FINAL" tab ~ although he is aware of the T&M nature of the trouble shooting).

Does anyone have tips on finding the elusive neutral?

Thanks in advance - not only from me (so I can move onto the next job), but also from the HO.
 
Re: Troubleshooting ~ elusive neutral ???

Originally posted by hardworkingstiff:
I'm sorry, but I'm not smart enough to follow what you are saying.
Click to expand...
I doubt that :D

Can you try some more with different wording?
Click to expand...
Yes... I just got back and the mind was still moving faster than the fingers.

Here we go....
Doing a job in multi-family property. The Home Owner (HO), stated that the GFCI in the 3rd flr "was not working properly". I removed the GFI, noticed the wiring was on the "LOAD" side - and proceeded to put the wires on the "LINE" side". After switching the CB back on, here's what I found:
- tester shows Hot is on ground
- lights do NOT work in the apt. (they are on same circuit)
- readings across L1 to N = 0v - but show continuity
- readings across either L1 or N to ground show 120v

I began the task of tracing the line back to the panel, and discovered the HO's brother-in-law(BIL) "once worked for an EC"...that would explain the buried boxes, BX run into plastic boxes, etc. The complete path has NOT been established.

What I am asking is for any tips on actually locating a loose/broken neutral. The home is 80 or so years old, no knob & tube wiring - old cloth covered BX is used. I know I am basically asking the impossible - but any help is help nontheless.

The GFI I removed had 1 12/2 BX entering the box. Very strange that disturbing THIS particular device would affect the whole apt.

Is that bit clearer? I know I have slowed down since I just ate.
 
Re: Troubleshooting ~ elusive neutral ???

Celtic If this is the only receptacle in the bathroom then there shouldnt be a load circuit on the GFCI receptacle?

try putting the line and load together on the line side of the GFCI and see if your neutral returns? If it does then you have a multiwire circuit running through the GFCI receptacle and needs to be pig tailed. to line side only. Remember a GFCI receptacle opens both hot and neutral when it opens. :D

Edited to add:
300.13(B) Device Removal. In multiwire branch circuits, the continuity of a grounded conductor shall not depend on device connections such as lampholders, receptacles, and so forth, where the removal of such devices would interrupt the continuity.
Click to expand...
This is why the pig taile to the device is needed. ;)

[ July 07, 2005, 09:51 PM: Message edited by: hurk27 ]
 
Re: Troubleshooting ~ elusive neutral ???

I understand what you are saying hurk...BUT...even w/the device removed, the condition (L1 to N = 0v; L1 or N to G = 120v; no lights, etc) remains.

The box where this device is contains ONLY 1(one) 12/2.
 
Re: Troubleshooting ~ elusive neutral ???

Guess I should have read more?
If there is only 1 hot and 1 neutral in this box then the only explaination is the neutral was making connection to the box or BX for return path. I have a Green Lee tracer that will find it but it cost about $550.00. I would be lost with out it. A toner can trace it also, after maping out the circuit. If you only turn on that circuit then check which outlets have the hot then place a toner and follow each outlet(this includes lights also) untill you find either a outlet with tone but no neutral or outlet with no neutral or tone. Then go back to last outlet and check neutral connection. Check at the lights first, this is where most circuits are fed to first. :)
 
Re: Troubleshooting ~ elusive neutral ???

$550 would save the HO about the same in T&M - and add a nice tool to my arsenal :) What is the model number?
 
Re: Troubleshooting ~ elusive neutral ???

I've used the Greenlee 2008 for years now.

The device turns what it is connected to into an RF antenna, and the handheld sniffs the RF field.

The transmitter doesn't like driving conductors that are energized. It still works, after a fashion, and indicates the presence of the voltage on the circuit, but the handheld sniffer's field following is less ambiguous when the circuit is de-energized.

Lastly, because the sender is broadcasting an RF signal, a conductor (as antenna) inside an metal shield, such as BX, will have little to no traceable signal for the handheld sniffer.

One can put the RF on the BX metal sheath and thereby trace the cable route, but if the sheath is laying up against other metal, say a water pipe, the RF will take off on the water pipe as well and yield a false route. You have to keep your wits about you with metal sheathed wiring methods.

The Greenlee 2008 is a wonder with nonmetallic methods and K & T.
 
Re: Troubleshooting ~ elusive neutral ???

the question remains about the lost lights. Were the lights working, then not? If you only, absolutely only, turned off the breaker, and eff'ed with the GFI, there are probably a few other options, but the most obvious are:
1.that there is a loose wire connection behind the bath outlet
2. that you corrected the reversed polarity and now have a hidden complex current path that is not logical
3. that it was serendipitous that the lights went off, and the bulbs need changing
4. that the breaker is actually still off and the power readings are coming from a neutral and a reversed polarity.

One of the best tools I ever used was the very good Greenlee touchless, the adjustable one which is about the size of a regular voltage tester. Since it could tell power without a return path, I could isolate the hots. One of the problems with mixed up wiring, where neutrals are shared and the polarity gets reversed, is that corrections multiply the problems, and voltage, with little current potential, makes neutrals look like hots to the tester. They used to sell waterproof "credenza" lights (an insulated bulb holder with two leads) and these are a great way to check that there actually is power, not just voltage.

Sometimes you really need to stop, give up trying to recoup lost time, relax, and get simple with what is happening. When all is lost, take all the fixtures down, the outlets out, the switches out of the dead circuit. Remember that there is a reversed polarity problem that needs to be fixed irregardless of whther you get the lights working again, so time is not your enemy or something to get guilty about.
1. start from the panel using continuity and double checking to find first outlet, switch, or multiple outlets if hidden junction boxes. You need to remove the ground and neutral at the panel as well (remember all is lost). use all the different combos of wire nutting the 3 wires to prove you have the right wires going where. make em, break em and just do two, etc.
2. when you find the first box, your life will get easier. But there is something you might want to do if it doesn't seem to be solving itself. Drag an extension cord around and using a tester, see if any of the neutrals or grounds still will complete a circuit, hot from the extension cord to tester to both ground and neutral at each location ( you have disconnected both from main panel and there should be no return path. remember all was lost, don't give up). If there is a shared neutral, your voltage may be from another circuit's neutral.
3. from first outlet find next with continuity, and so on. switch wires to make sure hidden jubction box(s) has not reversed wires.

I did so much of this kind of work that once in a while I was the problem because I wasn't thinking ahead when I started fixing things. If you do a lot of this type of work, keep a full tablet and write every thing down. It will also help with keeping track of switched wires, completed runs, and will help you keep it clear without having to keep it all in your head.

there are also cheap signal toners by GB. Sometimes the signal devices help and sometimes they don't.

Keep us informed, good luck and don't feel bad

paul
 
Re: Troubleshooting ~ elusive neutral ???

Celtic, the last thing you did was installing the GFCI correct. The cable was BX. Maybe when installing the GFCI correct the wires shorted out just inside that end of the BX. Can you get power on that circuit yet after disconnecting your wires from the GFCI recep.?
Jim
 
Re: Troubleshooting ~ elusive neutral ???

I was just gonna say I'd be looking for breached insulation on the BX sheaths that BIL trimmed.

It looks like Jim beat me to it.

From the symptoms the only way I can think of that that would happen is the hot and neutral would have to have shorted to the sheath and then blow a cheesy BIL neutral splice free. Sounds like a long shot but if it happened you'd have a hot sheath somewhere. Or at least there would have been at one time.
 
Re: Troubleshooting ~ elusive neutral ???

I still say that if the neutral path has been bad for awhile and was temperarly getting is return through the neutral in the GFCI box by contact between the neutral and the box or BX? When he fixed the GFCI wiring he opened the grounding connection and thus opened all the neutrals. But the other loss neutral connection does have to be found or new home run ran?
 
Re: Troubleshooting ~ elusive neutral ???

Originally posted by physis:
I was just gonna say I'd be looking for breached insulation on the BX sheaths that BIL trimmed.

It looks like Jim beat me to it.

From the symptoms the only way I can think of that that would happen is the hot and neutral would have to have shorted to the sheath and then blow a cheesy BIL neutral splice free. Sounds like a long shot but if it happened you'd have a hot sheath somewhere. Or at least there would have been at one time.
Click to expand...
OMG..some of you guys are gonna put Ms.Cleo outta business !!!

Here's today's scoop...
- found a BX cable w/ HOT sheath (good call phys)...I was in awe as my 10 year old GreenLee tick tester was able to trace the line - behind the 1/2" rock wall!

- after another 9 hours of dropping every fixture, opening every j-box and device box AND asked the HO and BIL multiple times "Are there any buried boxes?" The HO finally 'fesses up ~ "...hey, BIL...remember about 10 years ago when you ran this AC line and you got shocked?" ...."oh, yeah" mutters the very drunken wanna-be-electron-tamer- BIL . Turns out there IS a buried splice ~ in the wall in first floor (we are having issues on the 3rd floor) ~ good call Jim/Phys.

Inside the wall is an old BX attached to another old BX by means of the conductors. I stab at it w/Mr. GreenLee and we watch the arcing and sparking on the neutral. I jerry-rig a splice up and the lights that weren't removed on flr 3 now work. The BX jacket was not continuous (as there was no box - just a "free form" splice) and that would explain the "hot" sheath I found.
What a comdey show. After 34 man-hours removing everything (including what's bolted down) the answer is literally right behind the HO's head ~ in the wall behind where he was sitting at the kitchen table on flr 1.

So come Monday, we will pull a new cable from panel/basement to an ACCESSIBLE location in the 3rd flr apt...and rehang all the ceiling fans, etc.

Thanks for the help guys.

Now here's something I have never seen (again)...the GFCI that was at the "root" of this...I left it installed and wired properly while the N was still reading HOT...about every 5 - 10 minutes it would "trip". Anyone ever see/have an explanation for this?
 
Re: Troubleshooting ~ elusive neutral ???

Originally posted by hurk27:
I still say that if the neutral path has been bad for awhile and was temperarly getting is return through the neutral in the GFCI box by contact between the neutral and the box or BX?
Click to expand...
it's been "bad" for 10 years...with all the activity in the house (moving boxes/furniture, other trades, etc) it reached "critical mass" and quit. The splice I found (I wish I had a camera phone) was in free-air...the noodle was hanging by a thread - interlock your index fingers at right angles to get an idea...oh yeah, it had NO box, wirenuts, tape, BX sheath was non-continuous, etc.

Originally posted by hurk27:

When he fixed the GFCI wiring he opened the grounding connection and thus opened all the neutrals.
Click to expand...
No.
The box I opened (GFCI) had 1 and only 1 12/2 BX in it.
In spite of all our work, there are STILL buried boxes, flying splices, etc. Some will only be found when - and IF - the new HO does a complete rehab.
 
Re: Troubleshooting ~ elusive neutral ???

That's why I get all the chicks :D

The GFI has a little power supply in it that runs off the line connection. If it doesn't have a useful voltage level it wont work right.
 
Re: Troubleshooting ~ elusive neutral ???

I was actually startin' to get a little concerned that somebody might be offended by that. All this polical correct junk and acute sensitivty disorder nowdays. :D
 
Re: Troubleshooting ~ elusive neutral ???

was temperarly getting is return through the neutral in the GFCI box by contact between the neutral and the box or BX?
Click to expand...
If the neutral's hot and it's because of an insulation breach to the sheath, and the breaker's still closed, then you know BIL doesn't have the sheath bonded. Beacause the connection between the hot and neutral is through the sheath.

Besides, I had no doubt the BX wouldn't be bonded.
 
Re: Troubleshooting ~ elusive neutral ???

Ok sam you got it this time :D

But what I was thinking was lets say the BX sheath was bonded and long ago when the broken neutral connection was still good when BIL installed the GFCI receptacle, while pushing it back in the wall the neutral mad contact to the BX sheath but nothing happened so it wasn't noticed. Then at some point in time the neutral connection in wall get corroded and looses connection but because of the neutral making contact to the BX the circuit still works. Now come along Celtic and goes to find out why the GFCI receptacle doesn't trip and removes it from the box, the neutral now no longer is making contact with BX and when circuit is re energized nothing works. A little trouble shooting finds the neutral hot which would indicates loss neutral.

Well thats what I was thinking but glade he found it I hope all of it gets fixed because it sounds like a fire waiting to happen!

Good job Sam ;)
 
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