Strange problem call today

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ptonsparky said:
That's a fun experiment.

I settled on Flukes T+Pros a few years ago. We all have the same so we can all relate. I used three on a problem circuit and it was interesting to see the voltage would change depending where the meters were placed. They are not low impedance but do put more load on a circuit than my 87s.
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i'm partial to the discontinued fluke 12's for the reason they put a 2k shunt load
on the circuit being measured. eliminates ghost voltages.

a few years back i had one that was nuts like this, and i hunted and
hunted. posted here, actually took advice and listened to something
besides my own genius, to no avail.

turned out to be a combination of one side of the main breaker had high
impedance, combined with a bad service entrance neutral.
 
Does anybody do like I do and carry a rubber pigtail lamp socket with like a 15 or 25w bulb in it for testing? Use it with your high impedance meter to provide a load so you get an accurate reading. Use it by itself to test receptacles or to check wiring. I use it often on those jobs where the customer removed all the 3 way switches and couldn't remember what went where. I suppose you could even go one better and use a 240v bulb. Then you can use it on 240v circuits and tell the voltage too.


-Hal
 
jwnagy said:
I got a call from a friend today that he was having some problems with the power in his house (single phase). I went over and found a hundred ninety-eight volts on one phase and 57 volts on the other phase. I automatically assumed that he had somehow lost the neutral coming into the house. I went outside and removed the cover from the meter socket and check the power coming into the house (service drop). Everything looked the way it should, 240 volts phase to phase 120 volts ground to phase. When I went back into the house and looked at the panel I could not find any loose connections on the neutral bar or the neutral coming into the house on the lug. Everything seems to be the way it should.

What I find baffling is that exhibits all the symptoms of a lost neutral yet I cannot find a missing neutral. Turning switches on and off in the house affects other circuits. I find myself leaning in the direction of the power company yet the power company says that the power coming into the house is fine.

I'm also wondering if it could be a problem with the main breaker. I did find a little bit of water coming out of one phase lug on the main breaker which happens to be a 100 amp Cutler Hammer main breaker, and I wonder if the problem might be there. The service entrance cable is ancient, an old clothbound piece of service entrance cable installed in 1969. I've been telling him for a while that it needs to be changed and I hope that this convinces him. Water is apparently leaching through the outer cover and running down along the conductors into the panel but very slowly.

Any opinions out there on what the problem might be besides me being a big dummy. ������

By the way, I've been an electrician for nearly 40 years and a master in Maryland for the last 28 years. This isn't my first rodeo, but this one has me a little baffled.

Jeff
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Exactly where did you place meter leads when checking voltages? If in the house you placed one lead on the neutral bus, it could be possible you have a bad connection in the lug where the incoming conductor lands, test directly to incoming conductor, if result is still same the open conductor is further upstream toward the source. Since you have good readings at the meter (presuming it is still loaded the same when testing) then you are before the open conductor. Again make sure you aren't missing bad connection in the lug in the meter socket. If you eliminated all connections, then something has happened to the neutral in your SE cable. Verify that by turning power off and setting up some sort of jumper to do a continuity test across that cable.
 
hbiss said:
Does anybody do like I do and carry a rubber pigtail lamp socket with like a 15 or 25w bulb in it for testing? Use it with your high impedance meter to provide a load so you get an accurate reading. Use it by itself to test receptacles or to check wiring. I use it often on those jobs where the customer removed all the 3 way switches and couldn't remember what went where. I suppose you could even go one better and use a 240v bulb. Then you can use it on 240v circuits and tell the voltage too.


-Hal
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I used to carry seriesed 120v lamps but quit. I started working with 480 more often than not. Just wasn’t worth the risks.
 
mopowr steve said:
I think the neutral conductor within that SE cable has discinerated.

A couple years ago I had a guy call having problems with his stove. There was a SE cable used to feed his stove receptacle that ran thru a crawl space and it was not supported to the joists. Part of it laid on soil, and wouldn’t you know it; after cutting the jacket off where it touched the soil it revealed neutral strands that were reduced to fine looking hairs until there was no connection left. Crazy.
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Mopwer - you da man!

The photo says it all.

The day I originally posted was the evening I made the initial call...in the middle of a torrential downpour. I was kinda limited in what I could measure outside. I went back Saturday morning (nice clear day) and found this within 15 minutes.

Someone had poured a slab for the condensing unit right below the meter and sleeved this in a piece of PVC.

Thanks to everyone. If you were here with me I would give you each a bottle of Apple jack.

Jeff
 

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Little Bill said:
Was the poured slab setting on this cable and PVC sleeve?

All you lost in that corrosive mess was the neutral?
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The concrete was not on the cable. It was in a sleave. I looks like the cable was compromised back in 1969 when it was first installed and water infiltrated the cloth jacket...my best guess about the reason for the failure l...even though it took 50 years. It's amazing that there was any power at all in the panel, or that there wasn't a fire.

When I cleared out the sealing material in the sleave I couldn't really see the damage clearly, just a hint of what might be in there. When I gave the SE cable a tug, it broke!
 
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