I have been using a Progressive 'surge' surpresser for a number of years now. It has the ability to monitor the power coming into my coach. It has, on several occasions, alerted me to the fact that the power coming in to my coach was low voltage-as low as 103 volts- which as ed6713 indicated, could be harmful to A/C's and other electric motors. This problem is not limited to certain, off brand campgrounds. I found this problem in very large, prominent campgrounds like Disney's Fort Wilderness, Hershey High Meadow, and most recently, Sugarloaf Key KOA in Key West. It got to the point where the surge protector would shut down the power to my coach and reset a short time later. I feel that with all the electronics in today's coaches, it is well worth the investment of a few hundred dollars to protect the coach.
JMHO.