This is a copy of the post on the casita
forum for those that are not members over there.
Posted 24 July 2010 - 10:58 AM
I have been meaning to purchase a power line surge protector for our Casita. I am not the type that would dream of plugging a TV or home stereo system into a home plug without some sort of surge protector, but here I am three years into this new camper without any surge protection. Just think what a high voltage spike could damage: converter, refrigerator
, AC, sound system etc. Enough to really ruin a trip!
What I wasn't prepared for was the cost of commercial surge suppressors for campers/RVs. It appears that a simple inline protector starts at about $80. Hard wired units that protect against low voltage or power line frequency problems quickly cross $300. These may well be worth the money for peace of mind, but I just want basic protection from over-voltage spikes. Three MOVs (Metal Oxide Varistors), a plug, socket and short section of chord shouldn't cost $80. I went to the shop and found the parts left over from past projects, but since I assume most readers of this Forum are not ham operators and pack rats, I tried to track down a source for these items.
Radio Shack MOVs (part 276-568) about $2 each X3
30 Amp 3 prong female receptacle (Camco) about $6 any RV store
Short 30 amp male molded plug/chord about $10 any RV store
Attached Image: KAMCO parts (Small).JPG
Male Plug and chord and Female receptacle
Attached Image: MOVs (Small).JPG
The three MOVs are mounted across the hot and neutral wire, The hot and ground terminal, and the neutral and ground terminal. All three are needed to protect against common mode spikes (typical of nearby lightning strikes). The Camco receptacle has enough room to hold all three MOVs without any modification.
Attached Image: Labled receptecal (Small).JPG
Finished labeled project
Why would you not want to do this? There is no liability or damage insurance that is typical of commercial products
I got the CAMCO recepectal from Dixie RV in Newport News, VA. It was some years ago for a project I never completed so I guess prices have gone up (high price of plastic I guess).
You could do the same project with a short 30 amp extension cable and a simple 110 volt electrical
junction box in the middle. Cut the cable in the middle and mount the MOV's in the box. I was just using what I had on hand.
Not much at drawing schematics, but I copied the installation diagram from the CAMCO unit.
In a perfect world, two MOVs would be enough, but is either the neutral or the ground lead are not functioning, a common mode spike could cause damage.
Attached Image: MOV Placement (Small).jpg
Jeanne & Gil & Oliver
16 foot FD 2007
2006 Toyota Highlander V6 FWD
Factory tow package
Hensley CUB sway/WDH hitch
Jeanne & Gil & Oliver
(the dog that owns us)
This is a copy of Jeanne & Gil's post, for your convenience. I did not make copies of of the other replies.