120 volts on my neutral.

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bernardmulherin1978

bernardmulherin1978

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augusta georgia
I am currently working in a old paper mill , graphic packaging, and my task last week was to add one circuit in for one of the supervisors in his office , he has one circuit in already and its overloaded. I add the circuit in, pulled it in # 10, its atleast 200 feet , the panel was barely legible , barely workable , it was down right sad the condition its in, but all we are doing is adding a circuit in. I assume it was 120/208 but not sure , this plant was built in the late 70's or early 80's so it could be some design thats before my time. In the pipe I'm using there is a ground , yellow, white , and a blue , I pulled a black and white 10. I hooked everything up the way I wanted , separating were I saw fit. The plant goes to land the circuit I pulled and showed 120 volts on the neutral , so I go and make sure I didnt cross some wires ,, it can happen sometimes , and couldnt find anything wrong , now I know you can have residual voltage , voltage on the neutral when there is a voltage drop , but 120 volts. Can someone please offer some input on this , is this possible or ????????


Bernard J. Mulherin
 
bernardmulherin1978 said:
I am currently working in a old paper mill , graphic packaging, and my task last week was to add one circuit in for one of the supervisors in his office , he has one circuit in already and its overloaded. I add the circuit in, pulled it in # 10, its atleast 200 feet , the panel was barely legible , barely workable , it was down right sad the condition its in, but all we are doing is adding a circuit in. I assume it was 120/208 but not sure , this plant was built in the late 70's or early 80's so it could be some design thats before my time. In the pipe I'm using there is a ground , yellow, white , and a blue , I pulled a black and white 10. I hooked everything up the way I wanted , separating were I saw fit. The plant goes to land the circuit I pulled and showed 120 volts on the neutral , so I go and make sure I didnt cross some wires ,, it can happen sometimes , and couldnt find anything wrong , now I know you can have residual voltage , voltage on the neutral when there is a voltage drop , but 120 volts. Can someone please offer some input on this , is this possible or ????????


Bernard J. Mulherin
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They have the hot already connected and on by chance?
Sounds like a “disconnected” neutral
 
What kind of meter are you testing with? There may be an induced voltage on the neutral, the high impedance meters (like a fluke 115 or T+Pro) don't load the circuit so you get ghost voltages. Try a Wiggy if you have one.
 
Check at the panel for voltage phase to ground, if you have one phase reading 0 volts to ground, most likely an unbonded transformer, and a circuit shorted to ground. You would also have one phase showing 208 volt to ground.
 
bernardmulherin1978 said:
120 volts to ground , in this situation the neutral was being shared , isnt 120 volts on a neutral a little much on a 120/208 service


Bernard J. Mulherin
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Neutral to ground voltage should be zero whether it's a part of a Multi Wire Branch Circuit or not, but you haven't fully explained where you are getting your voltage readings from. You also said you pulled a black and white wire into a panel so where is this shared neutral?
 
Its being shared with one of the other Hot wires in the pipe , there were two hots and a neutral already in the pipe , so the circuit would have been on with the neutral I shared , I know you would read some voltage on the open neutral at the panel , it was being shared in the office , and the circuit was on , but isnt 120volts a little high.


Bernard J. Mulherin
 
It may not be an open neutral, that’s why you need to test voltage at the panel first. If the transformer neutral was not bonded, everything would still work, but neutral voltage to ground can be anywhere between 0 and 120 volts depending on a fault between one of the hots and ground. It will not trip the breaker until a fault happens on another phase to ground.
 
I assume this is a MWBC from the sounds of things. Possible not pigtailed somewhere in the box and an outlet with a broken tab used for the neutral splice (loaded neutral) ? Although if it were that you would be reading 120volts on neutral to ground from the outlet not a panel. (Probably just added to the confusion)

Need to know where your measurements are taken from.
 
120V to ground sounds high but I've gotten voltage issues when someone ties neutrals together in a Jbox and it feeds unbalanced loads back on an unrelated neutral.
 
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