[Shamu406]

Been very happy with our portable external, double protection since the built in one is OK.  One wag said like wearing both a belt and suspenders and I know a few who do exactly that.  Ours is Progressive EMS, not cheap but neither are repairs due to big surge.  Here is a link to one source, there are probably others less expensive:
http://www.makariosrv.com/progressive-el...ems-pt50c/

Thanks to both of you for the replies and info.
I ended up buying the Progressive Industries SSP50 Smart Surge

• 240V/50A
  
• 1650 joules
  
• 45,000 amps
  

Hope this is sufficient to safe guard my coach. It is not the most expensive one.