Allan:
I whipped up three drawings that indicate three overload scenarios possible
with incorrectly sized distribution equipment. They are on our web site
at: http://millersolar.com/case_studies/case_studies.html Click on Point
of connection. Click on any drawing to see a larger version.
To piggy-back on the question, and also continue my grounding on a glacier
question is anyone familiar with point dissipators and have used them. Todd
mentioned Nott LTD http://www.nottltd.com/lightning.html in my last string
and I have come acrooss Lightning Masters
William,
Wow - you're a master at whipping up drawings!
OK, I get the concept, and it's just as I described. The scenarios in
drawings one and two are OK as long as both busbars are rated 150A
(commercial) or 125A (residential.
You then show that the reason for the upsized feeders is to
Allan:
At the point of the short circuit, the amperage will exceed the rating of a
100 amp feeder. If the main panel had no extra breaker spaces, it could
still be subject to a short circuit if, for example, a wrench is dropped
into it.
I should add that I am not an electrical engineer nor
Wlliam,
If there were to be a short circuit in the feeder or the main service panel (
the one with no extra breaker spaces ), the solar's maximum 50 amp contribution
would be about the last thing to be concerned about. A short is going to result
in perhaps 1000s of amps coming from the grid into
William,
You may well find inspectors and others who will agree with you on this. I
remain firmly unconvinced. Yes, the code may be taken literally. . . . .and
also, sometimes, be taken out of context. I believe you are doing that here. It
is impossible to use words in such an airtight manner
Dick:
I do not desire to find building official who insist on a strict
interpretation of the code, but it is a reality in our jurisdictions. We
have to be pro-active and know the code better than they do, or we lose
money when we are assessed corrective actions that increase our
costs.
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