PARAPTOR...I think we are going to have to agree to disagree on some of the points discussed here. I agree that a surge suppressor, installed ahead of the transfer switch will protect the transfer switch when it is being fed from shore power. That installation will also protect the electrical lines that feed the breaker panel and of course, the items that are fed from the breakers in that panel. With that type of installation, what will NOT be protected is all of the devices in your camper/motorhome/toy hauler/etc. when running on Generator power because the transfer switch has opened the circuit (shore power feed) and that is where the surge suppressor is located, on the line or entry side of the transfer switch that has shore power coming to it.
Further, I will state that if you want all of your camper/motorhome/ trailer/etc devices protected while running on shore power OR generator power, the surge suppressor MUST be installed between the load side of the transfer switch and the breaker panel. This can be right at the transfer switch or at the breaker panel area BEFORE the lines go into the breaker panel main breakers.
Here is a link to the Progressive Industries web site that features the EMS-LCHW50.....
http://www.progressiveindustries.net/ems-lchw50
When you click that link, and the page loads, click on the tab that says "technical data"
When that page loads, click on the link for "print installation & operating guide"....it's right below the picture of the smiling motorhome.
When that PDF file downloads, scroll down to page 4 and you will see instructions for installing the surge suppressor AHEAD of the transfer switch. This install will protect your transfer switch and everything down stream ...breaker panel and all of the devices in your camper that the shore power feeds.
Now scroll down to page 6 of that same installation manual. Pay VERY CLOSE ATTENTION to the title of that section......and I quote...
" Installation AFTER Transfer Box for Protection from BOTH Generator and A/C power" (what we all refer to as shore power)"
This tells me that if the surge suppressor is installed using that method (after the transfer switch) you will have protection for your camper/motorhome/trailer/etc., but NOT for the transfer switch itself. This leads right back to my earlier post when I stated the very same thing. In the scheme of things, if something happens and the transfer switch has to be replaced, it is a less expensive item than the downstream components in the trailer....air conditioning units refrigerators, satellite system components, and anything else that may operate on 120VAC. And remember, this installation will protect your trailer whether you are running on shore power OR generator power.
PS....I currently do not have any type or brand of surge suppressor. I bought the Toy Hauler in late October and it has been parked for the winter. I am adding mods to it over the winter, and a quality EMS system is on my list of things to add.