120v to ground

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SiddMartin

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checkin out a remodel today and found 120v on the ground! Found the circuit causing the problem and this is what I believe is causing it: There is a short somewhere on the circuit and the ground is not connected to EGC causing it to "float" through the grounds that are tied together. What other possibilies are there? (I'm sure there is more).

I must say, it was crazy when I hooked up my voltmeter and saw 240 to ground! (Because Circuit A is 120v and the other 120v was coming from the ground "problem", they are on dif. phases.)
 
SiddMartin said:
checkin out a remodel today and found 120v on the ground! Found the circuit causing the problem and this is what I believe is causing it: There is a short somewhere on the circuit and the ground is not connected to EGC causing it to "float" through the grounds that are tied together. What other possibilies are there? (I'm sure there is more).

I must say, it was crazy when I hooked up my voltmeter and saw 240 to ground! (Because Circuit A is 120v and the other 120v was coming from the ground "problem", they are on dif. phases.)
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you hit the nail on the head, now its down to eliminating each device and junction one by one and making sure you have good bonds to ground and track down that short....
 
Start with getting the panel correct first with all other breakers off.From there slowly correct as needed.Are you sure you have not lost the neutral entering the house ?It is a comon failure and would give results you posted.
 
I had this same problem once. What I found was the HO wired a receptacle in the ceiling wrong. He wanted to switch the hot side so he could plug a ceiling light and to able to switch it on/off. The receptacle was melted. I think what he did was put the switch leg on one terminal and the hot on the other terminal, with the neutral. He tells me, well it never worked anyways. No wonder it didn't work, lucky he didn't burn his house down.
 
What type of meter are you using to see that voltage?

I suggest that you be certain to use a wiggy type meter. A high impedence digital VM may show volts that are only induced because that wire is not terminated ANYWHERE.
 
I hooked up my voltmeter and saw 240 to ground!
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Are you CERTAIN?
Just getting "240" to ground doesn't mean there is power on the ground...if you have a delta system and someone screwed up.

Did the hot leg read 120 to neutral?

Where did you test the ground to?

Lots o questions here.

I have seen 120v on ground wires, water pipes, conduit etc. Follow the path grasshoppa.
 
220/221 said:
Are you CERTAIN?
Just getting "240" to ground doesn't mean there is power on the ground...if you have a delta system and someone screwed up.

Did the hot leg read 120 to neutral?

Where did you test the ground to?

Lots o questions here.

I have seen 120v on ground wires, water pipes, conduit etc. Follow the path grasshoppa.
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Yeah, I had a good 120v from the hot to neu and 240 from hot to ground. And 120v neu to ground. The 120v on the hot and the 120v from the ground are on 2 sep. circuits. Once I started investigatin, I found the circuit putting the 120 on the ground, and with that circuit off, everything is fine. Started at the first JB in the basement and found the where the circuit splits and isolated the problem.
 
check with your utility company.

i have one utility that has a wild leg.
L1 to gnd - 120 volts
L2 to gnd - 240 volts
L3 to gnd - 120 volts

you may have this situation.
regards,
james
 
You should also ask yourself WHY it did not trip????
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I had this issue once and it put 120V thru the water piping.

The hot/ground shorted out in a ceiling jb (home run) and .........

1) burned (broke) the grounding path back to the panel and

2) remained in contact with the energized conductor.

The path back to "ground" included thru the plumbing. The route exactly, I don't recall.

wild leg on a 240 delta system is only ~208 volts.
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In these parts it is around 190V. The 208 designation really confuses the 3 phase issue so I always mark it "200V to ground".
 
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220/221 said:
In these parts it is around 190V.
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I thought it was L x sqrt(3).

If your L is only 110 then it could be 190, but for it to get to 240 then your L would have to be around 140. Tell me if I'm totally wrong on this one...
 
jerm said:
I thought it was L x sqrt(3).

If your L is only 110 then it could be 190, but for it to get to 240 then your L would have to be around 140. Tell me if I'm totally wrong on this one...
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You are correct

[edit: actually 138.56. V_high_LN/sqrt(3) = 240/sqrt(3). You can also take V_high_LN = sqrt{(V_LL)^2 - (V_LN)^2} ]
 
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