in fairness their voltage classifications are fairly odd, and it's hard to find solid motivation to use them unless you're filling in relevant paperwork etc.
NT
Energy savings, do you care?
Aug 04, 2020
146 Replies
On Saturday, August 8, 2020 at 3:40:12 PM UTC-4, snipped-for-privacy@downunder.com wro te:
able#
hes.
Have you seen the damage when a nearby lightning strike induces voltage int o a paralel wire run? I had a strike on a metal barn. It tripped the main c ircuit breakers for the property. It was parallel to the coax for a satelli te dish, and they were over three feet apart. It fried the Sat receiver. It then jumped into the telephone line. It fried the SLIC, and the five+ mile s of copper to the Central Office. Everything met code, but the induced cur rents did thousands of dollars of damage. It even fried a new SVGA monitor that wasn't connected to anything. The video cable was wrapped around the b ase, and there was no power cord. It fried the video input circuits. It als o caused a battery powered digital thermometer to explode, and it was over
100 feet from that barn.
A non-arbitrary number that stickes in my mind is that arcs above about 300 Vac will not self extinguish.. This is part of the reason that arc flash is a big deal at 470 Vac, but not so much at 240 Vac.
I don't know thw corresponding voltage for DC, but assume that it's lower, for lack of zero crossings.
Joe Gwinn
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