PI EMS-PT30C paid off a couple of days ago.

Like most I too camped for years without using any form of electrical protection for our trailer, 'though early on I did at least start checking the campsite source voltage with a DVM before plugging in and later invested in a Kill-a-Watt meter I would leave plugged in so I could monitor the voltage throughout our stay. I also eventually added a polarity checker to my kit which proved useful a couple of times when I did find a miswired campsite power post. As time went on and I began reading more and more on the forums about surge protector / EMS units it one day suddenly occurred to me that perhaps the reason the microwave oven in our KZ Spree had failed wasn't because it simply self destructed but because it had suffered some sort of error in the campsite source supply. :M Not long after I had the opportunity to buy a used TRC Surge Guard from an older fellow who was retiring from camping ... and in just the next few months was surprised at how many times it detected an error and shut off power to our camper. :E That confirmed it so a year later I sold the TRC to a friend and invested in a hard wire Progressive Industries EMS-HW30C which since then has also disconnected our trailer from campsite source power, 3 times last season and once this season already. During the season I keep our trailer parked here at the house, plugged in, and my EMS disconnected power to the trailer at least twice since I've had it ... seems source power line errors are much more common than one would think. :E I'm sold, and wouldn't ever plug into power from any source without protecting the trailer with some version of surge protector / EMS unit that includes low/high voltage protection. Considering the cost of repairing / replacing electrical devices in our camper the cost of one of these EMS units is a small price to pay for the protection it offers. :B