Originally Posted by bonginator
Thanks for the advice - but I am not an electrician. "Phase to neutral" and "Neutral to ground"? How would I check this with the voltmeter? Are there indicators for each on the voltmeter? Is there a laymen's way of describing this?
If your voltmeter plugs in to a regular outlet inside (or the 15 or 20 amp outlet on the post) you are measuring phase to neutral, this is where the voltage should be. There should be less than 10 volts between phase and ground.
There is certainly enough flaky wiring in many AS's to cause problems when you draw a lot of current (by running the airconditioner or three). But too many people using the park's power can cause the voltage to drop, which means that some AC units stop running and overheat. High current usage in one part of the campground can cause the voltage at another part of the park to rise (if the whole complex is fed with 3-phase, which is common).
You can check all of the voltages with a voltmeter and its little probes. It should be more than 100 volts and less than 135 from phase to neutral, and the same voltage should also be present from phase to ground. On a regular 15 amp outlet, the narrow blade is phase (black wire, brass blade and screw), the wider one is neutral (white wire, silver-colored screw), and the U-shaped or round one (green wire) is ground. You can also check the voltage inside when you turn the air conditioner on and off. Typically an air conditioner will cause the voltage to drop 5 or 10 volts inside the RV because of the resistance in the wiring. If there's a problem with the wiring in the park, it might drop by that much at the post and that's a good test. If you have a way to measure voltage at the post and inside the RV at the same time, you can tell a lot about the condition of things.
If the breaker on the post trips, you are drawing too much current (or the breaker is worn out.) This can be because the voltage has dropped and the air conditioner motor stalled (or your fancy automatic battery charger tried to keep up with the dropping voltage by drawing more current), or because the voltage was high causing more current to be drawn. Either high or low voltage can cause the breaker to trip, for different reasons.
The control panel, water pump etc should operate from 12 volts only, but if a spike has taken out the Univolt or its modern equivalent, this can kill stuff on the 12 volt
buss as well. If in the hot weather the battery has dried out, this can also cause the 12 volt
buss to get too high when you're plugged in, which can cause things to fail.