I have an APC battery backup and surge protector for my computer. It has a light, labeled "Building wiring fault." This light is on, and my computer will not start. I am unemployed and my landlord is useless, so I bought a multi-meter (Etekcity MSR-C600). Checking voltages at the outlet, I found the following:
- Hot to neutral: 117.5
- Hot to ground: 60.8
- Neutral to ground: 55.9
I then checked the voltage several other outlets. All of them have the same hot to neutral voltage, but the hot to ground and neutral to ground vary considerably. For example, another socket had:
- Hot to ground: 77.2
- Neutral to ground: 36.5
Is this sufficient to tell me the most likely cause of the problem? I'm guessing that hot and neutral are cross-wired or shorted in some outlet. Is that probably correct? This circuit is rather overloaded, but it does not seem to me like that should cause the low hot to ground voltage and the high neutral to ground voltage that I observe, unless there is a partial short in some appliance.
All the outlets in my apartment are on a single circuit. How do I go about locating and identifying the actual wiring problem?
Best Answer
The normal (if a bit optimistic) values you'd be looking for are 120V Hot->Neutral, 120V Hot->GND, and 0V Neutral->GND. It sounds like you pretty much get that already.
I'd be strongly inclined to believe the fault is not in the socket itself, but rather either in a connected appliance or in the wiring itself. The wiring TO the socket could be at fault, especially in a socket that had been habitually overloaded (and heated up as a result).
You might start by unplugging everything in your apartment and testing again. If that clears the fault, plug half of them back in, see if it reoccurs, then step-wise in that binary fashion narrow it down to a single appliance.
If that doesn't clear the fault, I would head to the breaker box and take measurements with your circuit's breaker in the OFF position. But this is probably where you should start looking for someone like an electrician, because this gets you into the (more) dangerous zone, likely having to remove the cover plate from the breaker box. But a measurement here would show whether the fault is inside or outside your apartment.