Problem with Grounded Outlet?

Question

Hi:

My girlfriend is having trouble with two grounded outlets in her house. She noticed it because a surge protector displayed a "building fault". The APC website says this light comes on in one of the three cases:

1. Overloaded neutral wire.

2. Reversed polarity (hot and neutral wires are reversed).

3. Missing ground wire.

I measured the voltage from hot to ground (~100 V), neutral to ground (~20 V) and hot to neutral (~120 V). The potential from hot to neutral is about 120 V as it should be, but it seems ground isn't at 0 V.

I checked the polarity, and that doesn't seem to be the problem.

What could the problem be? What do I need to do to fix it? Any further measurements that I could do to narrow it down?

Thanks in advance for your help.

Answer 1

Where are you getting 20 volts to ground on the neutral side?  Seems that you may have a appliance plugged into the ckt that may be shorted to a small extent.  I would check to see what is plugged into the ckt and unplug them to see if it cured the problem.  If it did thn plug things back in one at a time to see what the culprit is

Answer 2

a lot of times when grounds develop it's because you've started to have insulation break down.  The best solution is to call an electrician, and have him simply replace the outlet, however you can do that yourself.  It's hard to troubleshoot grounds on home circuits, so the best way to get a "sure" fix is replace the outlet, and if you have enough play in the wiring, cut back the ends of the wires about an inch.  Sometimes moisture gets under the insulation and corrodes the wires, causing a poor current flow.