I was surprised to find (from posts in prior similar threads) that many coaches, even late model ones, didn't come with them as standard equipment. Our little Monterey has one as a part of the transfer switch. If you have one it should be in or near the cord reel bay, where the cord wires into the transfer switch, and it will say Surge Guard (brand name) on it. It will look similar to this: http://www.trci.net/products/surge-guard/transfer-switches/50a-hardwires
In our house I have surge protectors for all my digital electronics, but they are insurance against failure of our whole-house one off the breaker panel. The Surge Guard is like that, a whole-house protector at the head of the power supply input. Presumeably you could put a 50 amp rated portable one at the park post and it wouldn't hurt if you had the hard-wired Surge Guard unit already and didn't know it; but at the same time the portable unit would only serve as overkill to absorb spikes before they got to the big hard-wired one. You don't really need the portable if you indeed have a built-in already.
Joel
