Originally Posted by m.hony
The $9.99 Camco one that plugs into a wall socket/receptacle in the trailer will work?
It is a round/oval yellow thing that plugs into a 110 receptacle and has an analog gauge on it.
I have one of those in my Cayo. In the winter, they're susceptible to static electricity buildup, which makes the needle move to one side or another by a few volts.
In the Airstream, I installed amp and volt meters permanently in the breaker panel. There's a thread here somewhere on airforums with photos.
[QUOTE=m.hony;1846881]I have several inexpensive multi-meters.
There may even be one in the trailer already.
How do I check the pedestal with a multi-meter?
Black lead in the center hole and red lead in each of the outer holes?
30 amp pedestal: measure the voltage between the left and right diagonal slots.
50 amp pedestal: Two voltages to measure, one between the center and left slots, one between the center and right slots.
Should get in the neighborhood of 120 volts on both legs?
If you're lucky. Few campgrounds will deliver that on a hot, busy day.
For RVs, anything over 130 volts would be a problem. In houses, excessive voltage is mainly a problem for 120v incandescent lights, which will have a reduced life with anything over 125 volts.
Again for RVs, anything under 110 volts at the pedestal would be cause for concern. Measured in the trailer with the air conditioner running I figure anything down to 105 volts is tolerable.
So here's the thing. Usually low voltage problems in campgrounds affect most of the loop to some degree. Typical practice is that they'll run 250 kcmil aluminum direct-bury cable, with a 200 amp breaker, and have it serve 8-10 sites with 30 amp service in a sort of daisy chain fashion. The cable goes from the big breaker box to the first site, then from the first to the second, then the second to the third, and so on. The idea is that all the sites supposedly won't draw the full 30 amps at once. But times have changed since the standards were set and most RVs have air conditioners and various other appliances and so the loop can easily draw close to 200 amps. Well at that draw with that cable you're doing to lose 1 volt for every 40 feet you go from the breaker box, so in a nice campground where things are spread out you've lost maybe 10 volts by the time you're halfway down the loop (I'm simplifying). There's less additional loss per site in the second half of the loop because they use the same size wire.
Usually on a hot day there will still be 120 volts at the transformer but depending on how things are set up it's pretty easy to lose 5 volts by the time the power gets to the beginning of the loop, so you're at 115, and then if you lose 10 volts halfway down the loop, well, half the sites are at 105 volts.
That's not unusual. And it's not just one campsite, it's usually a quarter to half of the sites in the campground, and so the manager can't solve it by moving people around.
On 50 amp sites this sort of thing is much less of a problem for a variety of reasons but mainly because these outlets are designed to deliver 100 amps at 120 volts (50 amps in each of two legs) and even the largest RVs don't draw nearly that much. The second reason is that 50a sites use 3-wire service and the load is balanced enough across the two legs that there isn't much voltage drop to speak of in the neutral, which cuts the total loss almost in half.