120volts H>N, 60volts H>G, 60volts N>G ?

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sw_ross

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I added a receptacle in a building today that was built in the 50's. Wiring is in EMT, using the EMT as the EGC. I added a receptacle by tapping off of an existing outlet. When I got the receptacle installed and I tested it my little plug tester showed and 'open ground'.

When I put the volt-meter on it I got 120 volts, hot to neutral; around 60 volts, hot to ground; and approximately 60 volts, neutral to ground. This confuses me! I've never worked in this building before so I'm not very familiar with its overall setup. I was just adding an outlet where the maintenance person asked me.

I'm not sure how you could get 60 volts neutral to ground?
Any input or ideas would be appreciated.

Thanks,
Sky
 
Thanks for replies

Thanks for replies

Thanks for the replies. The readings were taken at the new receptacle I installed with a Greenlee meter.

The original receptacle was removed, I turned it into a J-box and covered it with a blank cover, then flexed over 3 feet to where they needed the new receptacle (flex was required because of the location of the new receptacle). I included a ground wire in the flex and tied that back into the original box, which used the EMT as its EGC back to the sub-panel where the circuit originated out of.

I didn't/haven't opened up the sub-panel. I'd be interested to open it up and see if I get similar readings off of its feeders?

Thanks,
Sky
 
When you were asked what kind of meter the real intent of the question was probably to find out if it was high or low impedance meter. You want to measure with low impedance meter to rule out capacitive coupling. If you don't have low impedance or are not sure place a load on the circuit while measuring and you will still get low impedance type of readings. If you still get same or very similar readings you may have 60/120 supply somewhere in the circuit. If you have different readings but yet unexpected you probably have neutral or grounding issues somewhere.
 
sw_ross said:
When I put the volt-meter on it I got 120 volts, hot to neutral; around 60 volts, hot to ground; and approximately 60 volts, neutral to ground. This confuses me!
I'm not sure how you could get 60 volts neutral to ground?
Click to expand...
You've got a capacitor from line to ground and from neutral to ground as filters. With a floating ground, ground is elevated by the voltage dividing capacitors ... usually approximately equal.

REALLY messes up some instrumentation ... and fairly common in notebook computer power supplies.
 
GeorgeB said:
You've got a capacitor from line to ground and from neutral to ground as filters. With a floating ground, ground is elevated by the voltage dividing capacitors ... usually approximately equal.

REALLY messes up some instrumentation ... and fairly common in notebook computer power supplies.
Click to expand...

I like this explanation.

Bring a known good ground to the point in question and connect it to that point. If measurements are corrected you have a floating ground.
 
You do not have a system bonding jumper. The system is floated. Or...not very likely...the system is a "balanced power system". (Article 647)
 
don_resqcapt19 said:
You do not have a system bonding jumper. The system is floated. ...
Click to expand...

The OP's measurements and no bonding jumper - that happens easier with a separately derived system than with a service. The service is still grounded at the source even if system bonding jumper is not installed at the service equipment. If there are no grounding electrodes and no equipment grounding conductors incidentally "earthed" somehow the likelihood gets greater on the service supplied system.
 
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