I started camping over 50 years ago with my parents in a Scotty trailer. A lot of the campgrounds were new and the trailers rarely had any electronics in them. Now we have 50 year old campgrounds trying to maintain RV's drawing 50amps with two A/C's and countless electronics. The campground wiring is probably the same and can't keep up with todays demand. Unless you are in a NEW campground(few and far between) I think you are going to see that power sag 2oldman refers to. A good EMS is cheap insurance for the money I have invested in my RV. If you think it's a problem that doesn't really exist, you haven't been to enough CG's especially in hot weather. I suggest you get one and protect your investment.