jim mccloy
Member
Doing a job in an old house with Knob and tube and some newer wiring spliced to the old, and some of the receptacles are showing 30v L-G and 18v N-G. L-G I show 120. What could be some of the causes for this condition?
Voltage from neutral to ground
- Thread starter jim mccloy
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jim mccloy
Member
Re: Voltage from neutral to ground
I need to correct myself...I'm getting a reading of 120v from L-N...not from L-G. From L-G I'm showing 30v.
I need to correct myself...I'm getting a reading of 120v from L-N...not from L-G. From L-G I'm showing 30v.
Re: Voltage from neutral to ground
Hello Jim: I'm sorry I didn't continue on this topic.
I have a Micronta multi-meter with 10 megohm input. What this means is the meter is an open circuit across conductors with capacitance coupling. The meter is reading this coupling current translated to voltage.
You are measuring a low impedance system with a high impedance load.
Hello Jim: I'm sorry I didn't continue on this topic.
I have a Micronta multi-meter with 10 megohm input. What this means is the meter is an open circuit across conductors with capacitance coupling. The meter is reading this coupling current translated to voltage.
You are measuring a low impedance system with a high impedance load.
jim mccloy
Member
Re: Voltage from neutral to ground
Bennie: Why wouldn't this condition be the same for all of this guy's branch circuits (using my high impedance meter) throughout the house? This problem shows itself even on branch circuits WITH an equipment ground.
[ May 23, 2003, 10:39 PM: Message edited by: jim mccloy ]
Bennie: Why wouldn't this condition be the same for all of this guy's branch circuits (using my high impedance meter) throughout the house? This problem shows itself even on branch circuits WITH an equipment ground.
[ May 23, 2003, 10:39 PM: Message edited by: jim mccloy ]
luke warmwater
Senior Member
Re: Voltage from neutral to ground
Also, if the branch circuts with equipment grounds derived from a knob and tube circut, you have no equipment ground in the branch circut.
Also, if the branch circuts with equipment grounds derived from a knob and tube circut, you have no equipment ground in the branch circut.
jim mccloy
Member
Re: Voltage from neutral to ground
Bennie: I see what you are saying...it's just that I Know for a fact that the neutral and ground bars are bonded. I just installed a new service entrance. Maybe all the receps that I checked and found this problem (there all in the same room) are more than likely on the same branch. (they weren't marked before I replaced the panel and the home owner didn't want me to trace them out) and there's maybe an open on that particular branch.
Lukewarm...thanks. Your right...and someone maybe tied the EGC to the neutral of the knob and tube?
Bennie: I see what you are saying...it's just that I Know for a fact that the neutral and ground bars are bonded. I just installed a new service entrance. Maybe all the receps that I checked and found this problem (there all in the same room) are more than likely on the same branch. (they weren't marked before I replaced the panel and the home owner didn't want me to trace them out) and there's maybe an open on that particular branch.
Lukewarm...thanks. Your right...and someone maybe tied the EGC to the neutral of the knob and tube?
jim mccloy
Member
Re: Voltage from neutral to ground
The house was built in the 1930's and yes there is knob and tube wiring...and in some places it is spliced to newer romex coming from the panel.
The house was built in the 1930's and yes there is knob and tube wiring...and in some places it is spliced to newer romex coming from the panel.
jim mccloy
Member
Re: Voltage from neutral to ground
Bennie: That's quite alright. At least my suspicions are confirmed.
I talked with the homeowner today...I had to practically BEG him to let me put that fridge on a seperate circuit WITH an equipment ground. When he asked me why I felt it was so important to change it, I told him that his life wasn't worth that bowl of Ice cream that he'd be reaching for on a hot summer day in his bare feet.
Plus, when the fire whistle in town goes off in the middle of the nite...I can roll over and know it's not because of something that I did. (or didn't do).
[ May 23, 2003, 11:59 PM: Message edited by: jim mccloy ]
Bennie: That's quite alright. At least my suspicions are confirmed.
I talked with the homeowner today...I had to practically BEG him to let me put that fridge on a seperate circuit WITH an equipment ground. When he asked me why I felt it was so important to change it, I told him that his life wasn't worth that bowl of Ice cream that he'd be reaching for on a hot summer day in his bare feet.
Plus, when the fire whistle in town goes off in the middle of the nite...I can roll over and know it's not because of something that I did. (or didn't do).
[ May 23, 2003, 11:59 PM: Message edited by: jim mccloy ]
jim mccloy
Member
Re: Voltage from neutral to ground
CHA-CHING.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Voltage from neutral to ground
Jime: great answer "Plus, when the fire whistle in town goes off in the middle of the nite...I can roll over and know it's not because of something that I did. (or didn't do)." I'll remember that for some of the DIY's that post with questions.
Jime: great answer "Plus, when the fire whistle in town goes off in the middle of the nite...I can roll over and know it's not because of something that I did. (or didn't do)." I'll remember that for some of the DIY's that post with questions.
jim mccloy
Member
Re: Voltage from neutral to ground
Bennie: I see your point...I'm just covering my butt and providing the proper installation.
I guess it's not so much that it's a fire hazard as it is a matter of safety to personell.
I finished up with the job and the homeowner praised me for being diligent with things. After I put that refrigerator on it's own circuit WITH an equipment ground The problem with voltage showing on the outside surfaces went away.
I didn't make everyone happy though...there was another contractor working there doing some remodeling...he thought I was making too big a deal out of it.
[ May 25, 2003, 03:19 AM: Message edited by: jim mccloy ]
Bennie: I see your point...I'm just covering my butt and providing the proper installation.
I guess it's not so much that it's a fire hazard as it is a matter of safety to personell.
I finished up with the job and the homeowner praised me for being diligent with things. After I put that refrigerator on it's own circuit WITH an equipment ground The problem with voltage showing on the outside surfaces went away.
I didn't make everyone happy though...there was another contractor working there doing some remodeling...he thought I was making too big a deal out of it.
[ May 25, 2003, 03:19 AM: Message edited by: jim mccloy ]
jim mccloy
Member
Re: Voltage from neutral to ground
Good one Physis.
Good one Physis.
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