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[Phys-l] solar panel safety revisited




My attention turned to solar electricity today. It's a worthy topic. My thoughts were disturbing. I recall that the US appears to have above average domestic electrical fire statistics. It used to be said in our defense, that US homes have higher per capita ownership of electrical goods: dish washers, washing machines, clothes dryers, kitchen mixers and beaters, can openers, desk lamps, fans, heaters than elsewhere. (and its easy to respond that other nations have higher domestic electrocution rates.)

Currently, I get the impression that this equipment differential is vanishing, with a Chinese diffusion of such goods into Europe and elsewhere. But there is another factor - the line voltage; half that of some European and Asian countries, with correspondingly larger current draws. It is also the case that the US electrical code permits twisted wire domestic connections executed with spring caps. This detail alone provides insecure line connections, and that includes the ground paths intended to save us.

So it turns out that potential ignition points for US electrical fires are encouraged with high currents and insecure connections. And now, we are urged to consider green power sources - not least, high current solar panels.

And on this list, we see a natural response to the interest - in notes on using such power sources, originating in physics teachers. Moreover, there is an unusually high US population of lawyers, and a court system which will favor plaintiffs and their lawyers with very high awards in some cases. Because the juridical population is so numerous, their competition for business leads to aggressive solicitation of cases. Another factor: civil suits are calculated to target not just the culpable, but those whose culpability-pocket book product is favorable. And this list has a rather high proportion of older readers, who will likely have taken care to accumulate some savings for their retirement.

All of which is to say that when self-confident contributors offer advice on solar panel wiring, they are inviting retrospective searches of lists by lawyers working on behalf of fire victims who purchased and rigged high current solar panels; folks who can be encouraged to observe that they read what well-qualified people [like you!] seemed to say about wiring in panels and who put such advice to use.

Accordingly, it seems to me like a safer approach to point to URLs which offer NEC rule interpretation. Here are a couple....



<http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/PVnecSugPract.htm>


<http://www.altestore.com/howto/data/pdf/PV-NEC-V-1.9-opt.pdf>


Sincerely

Brian W