voltage on the "ground"

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scottp628

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looking for a bit of help. this is in a bedroom circuit, house about 25 years old. standard white NM wire(before colored wire and GFCI outlets). Adding a timer switch for the bath fan, I got hit by the bare ground wire. tested for voltage, 50 volts on the ground wire. separated the feed at the switch box. Voltage is correct from the panel, hot to ground, hot to neutral and neutral to ground. On the feed out, ( there are three outlets remaining on this circuit in the bedroom). I unplugged everything from the outlets. broke the ground connection at the switch and got 50 volts on the ground wire. removed the three old back stabbed plugs checked for loose connection there were several, checked wires for nicks or cuts. the wire casing looks like they were stripped with a razor knife and replaced with new outlets. Voltage dropped to 24 volts on the ground. I went to each outlet and "broke" the ground connection and tested for voltage. with the ground connection disconnected between the outlets there is still over 24 volts to ground. I thought a screw may have hit the wire in the wall. yet the voltage difference is continuous . I have checked outside to see if an additional outlet was tapped off yet I have not seen an additional outlet. The service is overhead on the opposite side of the house. I would appreciate comments, both helpful and comedic.
 
From your write up I can't tell which ground wire has voltage. If there is no spliced grounds in your outlet boxes, then there's a junction box that you have yet to find. If there are two or more grounds in the box, then unsplice them and follow the one which still has voltage (proceed with caution as the voltage may increase). With that said, you likely have two problems. One is the voltage is caused by a ground fault somewhere, and two, you have a resistive ground between the panel and point nearest to it where voltage is being measured.
 
PS: I've found it helpful to document what I did and the measurements I got, in the order that I do them... deductive reasoning always works better with explicit recall :angel:
 
Smart $ said:
PS: I've found it helpful to document what I did and the measurements I got, in the order that I do them... deductive reasoning always works better with explicit recall :angel:
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110 time out of 100, documentation completed at the time of the work is better than memory.
 
Take measurements with low impedance meter or wiggy to eliminate any voltages that are a result of capacitive coupling.

If you are getting shocked it is not from capacitive coupling voltages.

Make sure the equipment grounding conductor in question has good integrity - if it will carry a load without any significant voltage drop - it may not be great integrity but is good enough. Low impedance meter is usually good enough start for this measurement, but you may want to try a higher load like a 100 watt lamp.

If the ground path to the source is good your voltage about has to come from a neutral current flowing on the equipment grounding conductor, and will only be noticed when opening connections - find out which conductor at an opened up splice has potential to the one going to the source - the problem is somewhere downstream on that conductor.

If it were the ungrounded conductor directly connected to an EGC and EGC had good integrity - the overcurrent device would be tripping immediately.
 
scottp628 said:
looking for a bit of help. this is in a bedroom circuit, house about 25 years old. standard white NM wire(before colored wire and GFCI outlets). Adding a timer switch for the bath fan, I got hit by the bare ground wire. tested for voltage, 50 volts on the ground wire. separated the feed at the switch box. Voltage is correct from the panel, hot to ground, hot to neutral and neutral to ground. On the feed out, ( there are three outlets remaining on this circuit in the bedroom). I unplugged everything from the outlets. broke the ground connection at the switch and got 50 volts on the ground wire. removed the three old back stabbed plugs checked for loose connection there were several, checked wires for nicks or cuts. the wire casing looks like they were stripped with a razor knife and replaced with new outlets. Voltage dropped to 24 volts on the ground. I went to each outlet and "broke" the ground connection and tested for voltage. with the ground connection disconnected between the outlets there is still over 24 volts to ground. I thought a screw may have hit the wire in the wall. yet the voltage difference is continuous . I have checked outside to see if an additional outlet was tapped off yet I have not seen an additional outlet. The service is overhead on the opposite side of the house. I would appreciate comments, both helpful and comedic.
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I'm so confused maybe I shouldn't even post, but I have to ask what is ground? EGC, grounded conductor (neutral), Earth?
What two points did you measure from to come up with the assumption that you have voltage on the ground?

if we are talking about the grounded conductor (neutral/white wire) then yes you can have voltage returning through a load from the hot on it, very normal and only surprises those who think it will always be at 0 volts in reference to the EGC.

Try this trick:
Get a long enough extension cord that will reach the testing area, from a known properly wired receptacle, likely one close to the main panel and verify it is wired correctly, use this receptacle end of this extension cord and reference each wire you are seeking to test from it using the ground in the extension cord to test for voltage on the subject circuit wires, do not use the hot of the extension cord as it maybe on the other leg and can have 240 volts to the circuit under test, if you again find that you have a voltage then as mention get a lamp pigtail socket with about a 100 watt lamp in it, and connect it across the test leads of your DVM, this will remove any capacitive coupling voltages that may be present.

If in fact you are testing between the EGC (equipment grounding conductor) and neutrals you may have taken apart then all you are doing is reading the line voltage through the resistance of the load, this is totally normal and is a very perfect example as to why you don't do wiring without turning off the breaker! which was my next question Why are you hooking up a timer while the circuit is hot????

I hope maybe you can clear up some of the above mysteries and maybe we can point you in a more clearer direction.
 
Aw geez ... can't you just tell me what's wrong ? Do I really have to give you an accurate description and check back in to see if anyone posted any answers?
 
realolman said:
Aw geez ... can't you just tell me what's wrong ? Do I really have to give you an accurate description and check back in to see if anyone posted any answers?
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I might be able to tell you what is wrong, but I need accurate information of conditions before I can do so:p
 
realolman said:
Aw geez ... can't you just tell me what's wrong ? Do I really have to give you an accurate description and check back in to see if anyone posted any answers?
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It's that dang generation that grew up in 60s. That's whats wrong. All started back then with those dang long haired hippies started taking trips and never leaving the farm.

Sometimes it is pretty hard to give an accurate description of a problem when you really don't know what you are looking for. That Catch 22 thing
about experience.
 
Thanks for your help, I will go back and look further. When I find the cause I will post a reply.
difference in potential is between the EGC (bare copper wire in romex) and the Grounded conductor ( white one)
the panel in not marked. I was pulling the switch out of the box to trace and got hit by the EGC. I broke the EGC splice and saw a small spark jump the gap. my first post takes it from there.
 
scottp628 said:
Thanks for your help, I will go back and look further. When I find the cause I will post a reply.
difference in potential is between the EGC (bare copper wire in romex) and the Grounded conductor ( white one)
the panel in not marked. I was pulling the switch out of the box to trace and got hit by the EGC. I broke the EGC splice and saw a small spark jump the gap. my first post takes it from there.
Click to expand...

This is sounding like a lost neutral up stream but I'll leave that to you, make sure you check out the using an extension cord to use as reference point as I posted above, let us know what you find.
 
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