26 Aug
2015
26 Aug
'15
9:40 a.m.
On 08/26/2015 08:19 AM, Paul Koning wrote:
> Turned out there was a 120v potential between
the "dedicated" power for the computer and the printer which was plugged into
the normal building power.
>
> There was probably as much as an amp going thru the grounds from the terminals in the
building and the ground of the system. Miracle that he was not severely injured, and also
that the system was working at all.
>
>
Yup, in the first house I owned, i had a "computer room".
The previous owner had done some retrofits and installed an
outlet in a closet. I plugged a printer into that outlet,
and my computer (S-100, CP/M) into another on the opposite
wall. Some strange things happened, some chips got blown, I
didn't know why. Then, finally, I put my hand on the
printer and something connected to the computer and got a
big shock. Quickly investigating, I found a Romex staple
had been driven through the Romex, severing the safety
ground and tying it to the hot! This was back before outlet
testers were common items. Well, that explained some blown
chips, etc.
Jon