Ground gone hot


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Old 02-24-14, 06:04 PM
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Ground gone hot

A contractor was in today to plaster, the switch and the light box were moved. Now the ground seems to have gone hot.

I have not been able to take everything apart and see what is going on in there, but, any tips on what could cause this or what to look for when I open the light box up later tonight?
 
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Old 02-24-14, 06:11 PM
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Now the ground seems to have gone hot.
Not quite sure what that means.

You had a switch and a light moved. Was this done by an electrican or a handyman ?
Hopefully nothing got buried in the wall.
 
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Old 02-24-14, 06:20 PM
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Handyman is in just to plaster.
The lights were pulled to plaster around a new box.
Now the ground wire is hot.

Only thing I can think of is if the light was pulled and the a hot wire is now loose touching the box, causing the box to be hot and therefor the ground wire down to the switch (via travelers)?

I will only get a chance to get in there and take it apart in an hour or two.
 
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Old 02-24-14, 06:23 PM
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A hot wire should arc if it touches the metal box at the light unless the ground wire is not connected properly in the switch junction box.

Be careful when you check this out. Turn the circuit off and check your grounds.
 
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Old 02-24-14, 07:24 PM
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Why do you think the ground wire is hot. You didn't rely on a non contact tester did you?
 
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Old 02-24-14, 08:12 PM
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It gets worse (as does most things in this old home).

Ray, I did use a non contact tester, I do have an old contact tester I will bring upstairs tomorrow. Could the non contact be giving a false reading on the ceiling box being hot?

I used a Klein non contact tester, the ground is hot at the switch, so I went up to the ceiling light box, the wiring looks correct, the light box is hot. I pulled all the wires away from the box, only the locking nut touches the wires and the box. The box remains hot.
I removed ground from the ceiling light box to test, the box remains hot.

I moved on the first light box in the line, which is the next box, and this box is hot also. All the plaster surrounding the box is burnt black. There was a light on this fixture, but a hanging light so unlikely the burn was caused by heat from the bulb as the bulb is about 6 inches from the ceiling.

I honestly do not see how or where the box is becoming hot yet.

I had to call it a night so I shut power to the line until I can follow up tomorrow after work.

There is a light switch with travelers on the first light, I will disconnect those to eliminate one element and test again. But there are 2 more lights, one plug and 2 switches further down on this line.
 
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Old 02-24-14, 09:09 PM
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Usually as long as any wire is hot in the box..... a non-contact tester will show power.
That's its only job...... to let you know there is high voltage in the area.
 
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Old 02-24-14, 09:11 PM
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Could the non contact be giving a false reading on the ceiling box being hot?
Most definitely. Their false positive percentages are very high. At this point we do not know if the ground is hot so don't get ahead of yourself. Unless you have a neutral at the switch don't bother testing there for now. At the light with a multimeter, preferably analog test:
  • Black to neutral.
  • Black to ground.
  • Neutral to ground.
 
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Old 02-24-14, 09:30 PM
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Thank you guys!
My daughter has packed it in for the night so I will test tomorrow after work and report back.
 
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Old 02-25-14, 09:03 AM
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It's important to distinguish between the Grounded Circuit Conductor which is identified by the color of this Conductor which is White , and "Ground".

If the wiring of your house consists of metal cables connected to metal boxes, then the metal surfaces of the cable and boxes are "Ground". In a basic two-conductor, 120 volt circuit where the conductors are enclosed in metal armor , there is the 'Live" conductor ( color Black ) , the Grounded Circuit Conductor ( color White ) , and "Ground" . the metallic surfaces of the cable and outlet boxes.

The normal voltage-values for such a circuit is 120 volts, Black-to- White" and 120 volts, Black-to-Ground. If there is 120 volts, White-to-Ground, then either there is a faulty connection or the White Conductor is connected to switch terminals , a very common type of connection.
 
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Old 02-26-14, 06:42 AM
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I took a second look last night, if anything came in contact with switch housing, it arced (it was in a new plastic 2 gang box).

I pulled the switch, which is brand new, and replaced it with a new switch and all is fine. Have you seen this before?

This brings up a second question, as I change old wiring on a line, in sections, am I correct in wiring the new portions as a new install and grounding the box etc even though the end of the line is an old 2 wire (no ground) install?
I have started at the feeder panel to change the wire as we renovate, but it will take a fair while before the entire run has been replaced.
 
 

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