There is some protection built into the Progressive Dynamics converter but they do not tell you how much. I will be making up one of the testers, just a good idea before you plug into a pedestal. You hear horror stories of folks who have fried their system, how often that happens is open to debate but once is enough to mess your electrical system, and one neat, put it together you self testers can be found here http://www.myrv.us/electric/Pg/tester_30amp.htm The site by btw is a good one for basics.
At home I have a point of entry panel guard and on each of the major appliances and electronics a sure protector and a UPS (un-interuptable power supply) for the computer. The two or three layer surge protection devices is best. The home system does by the way work well. We had a massive surge that killed neighbors electronics and my UPS alarmed so some leaked past the panel guard.
In looking for information of what kind of protection for the trailer I was looking for some depth of information and found http://www.lightningcontrol.com/FAQ%27s.htm which I will book mark for future reference and stick in my folder of stock answers for RV forums.
There are two main actors Surge Guard http://www.trci.net/products/surge-guard and The second company Progressive Industries http://www.progressiveindustries.net
Both have a good reputation of customer service. I stopped in at my local RV establishment today and asked "how often do the portable ones walk off" and the lady said often, along with the cords. So I ordered a Progressive industries hard wired with remote. It is physically smaller than the Surge Guard in the hard wired version and I am seriously running out of room to stick stuff in with the electrical.
