[Elecraft] Low Voltage Supply Danger

[W3FPR - Don Wilhelm]

And I will add that we should be very cautious around batteries and battery
sourced power supplies too.  Batteries will produce a LOT of current if
shorted.  I once tested an 8 cell pack of AA sized NiCad batteries in a lab
for their short circuit discharge current - yes the current dropped off
rapidly, but was still sufficient to vaporize the copper in the #16 wire
leads attached to the battery pack.  Keep those battery terminals adequately
covered and safe from accidental contact.  The voltage may not hurt but the
results from the current can certainly maim and even kill.

73,
Don W3FPR

> -----Original Message-----

>
> Allen, KA5N wrote:
>
>  ...Can you imagine what would happen if you accidently shorted a ring
> across a fully charged ultracap of 20,000 Farads?  Goodbye finger(s).
>
> --------------------------------------
>
> That's a legitimate concern with our present 13.8 supplies as well. Twenty
> or thirty amps can be very dangerous if you get a piece of jewelry across
> the contacts. If you're unlucky enough to fail to make good enough contact
> to trip the crowbar or blow a fuse, you'll be frozen there as the ring (or
> bracelet) melts into your flesh.
>
> Almost everyone who has worked around aircraft knows someone
> missing a ring
> finger and sometimes a whole hand from just such mishaps. Working on a
> fighter one night at Lockheed Aircraft, I heard a power cart groan and
> looked at the next plane sitting wingtip to wingtip with the one I was in
> and saw smoke billowing from a partially-opened canopy and a tech
> unconscious inside. It turned out he had tried to replace a
> breaker without
> disconnecting power and dropped this screwdriver where it contacted the
> power bus bar and the side of the airplane. The metal shaft of the
> screwdriver literally exploded into globules of molten metal that
> caused him
> to jump up, smash his the back of his head on the canopy and
> knocked himself
> out. Other than a concussion he wasn't seriously hurt but the plane was a
> mess.
>
> That's one very good reason to be sure that 20 amp fuse Elecraft specifies
> for the K2/100 is in the power line.
>
> Ron AC7AC
>
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