Brought the thread to top to suggest another option for checking campground power circuitry and voltage. I would like to have the 200+$ E[lectrical] M[anagement] S[ystems] 30 amp hardwirable circuit analyzer and over/under voltage protection for the Burro
but we're in "our" camping season now and I decided to go with an inexpensive alternative for the moment. Shown is the Prime Products circuit fault checker and AC voltage meter (about $27 from Amazon Prime), a 30amp male to 15amp female adaptor (about $6 and free shipping when ordered w/ an Amazon Prime item), and a 50amp male to 30 amp female adaptor which I already had (probably from Walmart).
The Prime Products voltage meter has a simple indicator light
system to reveal correct or reversed polarity, open neutral and open ground. Also monitors line voltage. It can check circuitry plugged into an AC receptable in the trailer; however, IF it reveals a circuit fault, it is not possible to know if the fault is in trailer or campground circuits. Plugged directly into 15 amp receptable in the box on the pole (or into either 30amp or 50 amp receptables using the appropriate adaptor[s], the campground system is isolated from and tested separately from the trailer. Added benefit is very similar to the use of the "dogbone" portable surge protector to establish correct circuity and adequate voltage in site power box BEFORE plugging in trailer or even backing into site. I think for under $40, this is a LOT BETTER than stumbling blind into a miswired or inadequate power supply. I also think the operation is a bit simpler than standing in the rain trying to remember how to use a multimeter for circuit tests. What is not available at the price is auto-shutdown of power to the trailer based on circuit faults or over/under voltage; you must make the decision to refuse a site or camp without AC power and you must monitor line voltage in situations you believe might produce voltage "brownout" or severe voltage spikes.
I checked our trailer today (both the four AC duplex receptables inside and my home circuitry thru a 20amp extension cord that supplies "shore power" at home). Found no faults and voltage readout right on the nominal 120VAC. Turning A/C on high had the effect of dropping readout to 118volts.