> Something we have to remember that is often taken for gospel and that is
> the whole house rising to a given voltage together, which isn't quite
> true as it's phrased and isn't true at all in some older homes.
Take a look at the Cutler-Hammer product description, and Figures 4-1 and
4-2.
http://www.eaton.com/ecm/idcplg?IdcService=GET_FILE&dID=56325
The product brochure even goes on to state that IEEE recommends two-stage
(secondary MOV) protection at outlets in addition to a whole-house TVSS
unit. My own home uses a whole-house device at the service panel as well as
secondary protection devices in the shack (Leviton Hospital-Grade
receptacles with integrated MOVs).
What's confusing is to hear that placement of the secondary protection at
receptacles will cause an asymmetrical rise of the ground potential between
branch circuit grounds. I get the theory of that concept but is that what
really occurs during most surge events? I cannot imagine the IEEE and
respected commercial vendors like Leviton, Hubbell, Square-D, Cutler-Hammer,
etc. -- all recommending a practice that's counter-productive, even if that
practice helps them sell more product.
Paul, W9AC
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