panel mount TVSS - in subpanel too?

[Nate Nagel]

Hi all,

I have a Siemens breaker panel in my house that uses QP type breakers. I purchased a double breaker/TVSS unit to replace two 20A breakers in the panel. I figure that it is cheap insurance, even though I have no indications that there's issues with the power locally.

What I would like to know is this. I have a 100A breaker in this box feeding a garage/outbuilding at the back of the lot. This building obviously has a subpanel in it for the lighting, bathroom, water heater, etc. - would it be a worthwhile investment to buy another TVSS for that panel, or is one at the main panel generally sufficient for all forseeable issues? IF it makes any difference, this wiring is buried and all utilities (except phone, which is disconnected) are buried as well.

thanks,

nate

[John Grabowski]

I think the one at the main panel is sufficient. I would put any additional expense and time into making sure that you have a good grounding electrode system (Ground rods, water pipe grounding, interior metal piping bonded, etc.).