As we move nearer to summer, or we plan to attend a big RV rally, low voltage issues really do come to the fore. Pull into that "budget" RV park, plug into the electrical system, and prepare to cool down by switching on the air conditioner. But hang on a minute! Old RV parks often have an old electrical system--one that may well be under-rated for the needs put on it by present-day power-hog RVs. If the electrical system voltage is low--consistently below 104 volts--it can cause damage to RV electrical and electronic gear.
Your air conditioning system is one of the most easily grieved by low voltage. It takes a set amount of power to operate your air condition--it MUST have it. If the voltage is low, then the a.c. unit will still try and respond to your command to produce cool, but in the process, it will run hot. This puts a huge strain on the compressor motors, and given enough trouble, something’s gonna break--and we can gaurantee one thing: It won’t be cheap to fix.
How can your protect yourself? Buy, install, and use a power line monitor. On those hot summer days when everybody around you has fired up their a.c. unit, before you switch on yours, take a quick peek at your monitor--conveniently plugged into a wall outlet--and make sure the power is safely above 104 volts.We use ours as an added safety benefit against bad electrical wiring at the RVhookup. One of us gets in the rig before we plug into the power. The other plugs in the power, while the inside person verifies that the power monitor shows "good" wiring--no reverse polarity, no "no ground" situations--any of which are present can lead to safety issues. We’ll touch bases on these matters in a future blog entry.
Camping World sells a fancy power monitor for about $65. If you don’t want to spend that much, the use your digital volt meter: Set the meter to monitor AC voltage and carefully plug the probes into the large, rectangular blade slots of one of your wall outlets as shown. Check the voltage that way--but don’t leave the meter probes plugged in unattended! An alternative would be to build yourself a "plug in" cord set, using a wall plug, some "zip" wire, and a set of plugs to fit your meter. With digital meters so inexpensive, you can build your own for a whole lot less. 
