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sko1270 · Feb 20, 2008, 07:12 AM

Hello,

I started having an issue last night with my electric. All of the sudden my computers ups started beeping like crazy and I noticed it also showed an electrical fault. I tested the outlet with a 3 pronged tester and it showed an open ground. I also found 7 more outlets in the surrounding area with this condition.

I then tested with a voltmeter and it showed 120 between hot and neutral and 60 between hot and ground. I think it also showed 60 between neutral and ground.

Now this morning I went into my basement and noticed that the ups down there was also going crazy. But I could see the electrical fault light going on and off. Then it stayed off. I tested this outlet and it showed that it was good.

Any help would be appreciated.

Thanks

Stratmando · Feb 20, 2008, 08:08 AM

Start at the panel, since you have a good hot and neutral, this will help determine which recepticles, switches, and light boxes to check.
Follow the hot wire from breaker to where it exits panel, locate ground with that hot, verify
It is intact, and continue.

donf · Feb 20, 2008, 08:08 AM

Pull the UPS out of the circuit and see if that makes a difference. UPS devices cause more problems then they are worth, especially since most computer power supplies are designed to shut down if the voltage climbs to high or to low.

I don't know about you plug tester, but your voltage reading are dead on.
There should be 120 VAC between the Supply (Black) and Neutral (White).

When measured between measured against ground your readings are also correct. So I really doubt that your receptacles are or ground were giving you a problem. Like I said earlier, drop the UPS out of the loop and see how everything works.

sko1270 · Feb 20, 2008, 08:30 AM

Thanks for the replies.

I have a question for donf.

I am now a little confused. These outlets show 60 between hot and ground. But I have other outlets that show 120 between hot and ground and about 1-2 v between neutral and ground.
Is this normal to have some outlets showing different readings?

Thanks again.

donf · Feb 20, 2008, 08:59 AM

Depending on the type of circuit being examined, the circuit Pole should be 120 degrees between phases. The use of Neutral, is to provide a return residual voltage path back to the Service Entry Panel. From the main panel to the service disconnect. At that point Neutral and Ground are tied together.

The reason you see 60 VAC is that the ground is at the center point between Black and White. 60+60 equals 120.

I'm concerned that you see 120 between Hot (Black) and ground. Unless you are talking about a 240 circuit. Does the outlet have three wire conductor with ground, for example Black (hot) Red (hot) White (Neutral) and Bare ground.

However, the female receptacle should be designed differently than a normal 110 / 15 amp or 120 / 20 amperage. For example, 110 outlets use two vertical slots, one is longer that the other to identify the neutral connection point. 120, however, use the same two vertical slots to accommodate 110 plugs, plus there is a horizontal slot to signify that the outlet is 20 amp.

On the plus side, a 110 outlet can be used on a 120 line providing that the conductors (wire) between the breaker and the outlet are rated for twenty amp. (12/2).

Stratmando · Feb 20, 2008, 09:13 AM

Sko, You should have 120 volts between Hot and ground, and Between hot and neutral.
Should have ZERO between neutral and ground.
60 Volts is NOT normal.
Ground is NOT Center point between hot and neutral, Neutral and ground are at the same potential(connected).
This is not 240 Volts, if it was, then neutral IS between both hots. 240 volts between both hots, 120 volts from either hot to neutral or ground.

KISS · Feb 20, 2008, 10:19 AM

donf:

Your supposed to have 120 between hot and ground.

The 60 VAC is coming from something with a switching power supply ( likely a computer, a UPS) that's dumping voltage on the open ground through the RFI (Radio Frequency Interference) filter in the UPS or Computer. Once you remove the offending appliance, the voltage will return to nothing, but the problem is not fixed and the UPS isn't bad although damage could occur to devices connected to that ground and a stable ground which share the ground for communication.

An outlet can be bad. I've seen it happen to 250 out of 400 of them because of a manufacturing defect. The ground at the box could be bad. The outlets should have ground connected directly to the ground screw on the outlet ond pigtailed to the metal box.

If 7 outlets are bad, I'd start with a loose connection at the fuse box, otherwise your going to have to find the last one in the series that works or the first bad one and inspect the ground connections for integrety.