On 1/9/12 1:53 PM, Jim Miller wrote:
> Anyone have experience with the SurgeGuard?
> http://www.surgeprotectiondevices.com/ It installs as a shim under the
> power meter to provide whole house protection.
> The company claims protection for "sturdy white goods". I take that to be
> something motor driven. They specifically don't cover semiconductor devices
> although BGE Home offers a $10K insurance when these are installed which
> covers TVs, etc.
Sturdy white goods? Interesting turn of phrase.. Sturdy appliances
don't need much in the way of surge protection. A number of studies
have shown that most household appliances can take 1-2 kV spikes that
are short without too much trouble. The transformer in the usual
wall-wart, for instance, provides common mode isolation, and has enough
inductance that differential mode spikes don't get through. (although,
there's the whole interwinding capacitance thing...) Anyway..
The big problem is what's called "swell": a relatively long duration
higher than normal voltage, which basically cooks any MOV that has too
aggressively low threshold voltage. And of course, the cheap surge
protectors have low voltages because that sounds good to the customer
(ours clamps at 140V unlike those inferior 170V clamps)
If you have a problem with the neutral in the feeder (not all that
uncommon, as it happens) you could easily wind up with a slight
overvoltage on one side or the other, just enough to get those MOVs nice
In any case, this form factor (under the meter) is a very popular one
these days. It's easy to install, doesn't require wiring anything, etc.
google/bing for "Leviton 50240" for a typical unit. they've got the
datasheet there. Takes a 20kA nominal discharge current, clamping at
600/500/400V (not sure why L1-N is more than L2-N... L-L is 400V)
You need to have a decent ground (not RF ground.. just reasonably low
impedance) to give the common mode transients somewhere to go.
presumably, your neutral is bonded to ground at the service entrance
(and ONLY at the service entrance)
(something a bit more burly would be a Leviton 42120-1, but that's not a
meter base style.. but it does have filtering built in)
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