22 Aug
2000
22 Aug
'00
11:18 a.m.
and I thought I was being facetious! The risk is from the public and their
lawyers and not from the computers. If you have a public facility, and a
kid (age 8, say) sticks his pocket knife into an outlet and shocks himself,
the legal costs will bankrupt you, win or lose. Unfortunately, if that same
kid uses his pocket knife to cut into your terminal's power cord and shocks
himself, the resulting lawsuit will still bankrupt you, and, if you collect
admission, hence have cash on the premises, the severe cut in the back of
the head of the third guy to rob you on your first day will yield enough
legal cost to finish you even though it was only induced by his falling
through the glass door when you hit him in the head with a thrown 8" floppy
diskette.
Dick
----- Original Message -----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Tuesday, August 22, 2000 12:50 PM
Subject: Re: Lethal computers? (was: Goodwill Computerworks Museum is open
paid
>
> Sellam said that Goodwill should turn the machines on and let people
play
with them.
Richard said that that would create excessive liability exposure.
Just how frequent ARE fatalities from computers?
Very, Very rare. Injuries are rare as well (especially if the case isn't
open). I think we can discount RSI-type problems for a machine that will
only be used for a few minutes at a time.
Unless somebody opens the case, "connecting
himself to the mains through
your display" seems a little difficult.
Agreed...
IANAL, but I believe that if you did safety tests before the machines
were put into use and at a suitable period (3 months, 6 months, 1 year,
this would have to be decided) thereafter _and kept records_ you'd most
likely be OK (at least in the UK). Such safety tests should include (at
least) a visual inspection (no cracks in the case, no bare wires hanging
out of the power supply, correctly fitted mains plug, etc), a HV
insulation test (apply 1kV-2kV between the live/neutral wires of the
mains cable (strapped together) and exposed metalwork and make sure that
a suitably low current flows) and a high-current earth continuity test
(pass 10A, 25A or even more through the earth wire between the earth pin
on the mains plug and the machine chassis). The idea of the last test
is to ensure that if there is an insulation breakdown then the fuse fails
before the earth wire burns out.
You can get 'Portable Appliance Testers' that do the 2 electrical tests
mentioned above and give a pass/fail indication. I prefer to use test
gear that actually displays the insulation resistance and earth
resistance as I can then notice problems before they become serious, but
for less clueful people the pass/fail indication is useful I guess.
In my experience (and I would _not_ depend on this for machines on public
display) computers don't suffer from insulation problems. 1970's minis
(and earlier machines I suspect) were built with top-grade components and
I've never seen a transformer break down. And later machines are modern
enough that the components are still new enough not to give problems (and
in almost all cases components have been designed so they can't fail in
dangerous ways).
As I said I'd not _depend_ on this being the case -- I'd test it. But I
think the chances of a fatal electric shock from a computer are _very_
minor unless you're working inside a monitor or PSU (or some other
mains-connected area).
> 'Course there is the issue of mental anguish.
>
> In fact, the only dcocumented fatality that I've found from a
> microcomputer was from the frustration of serial interfacing: a guy > the owner of a store to get his new serial
printer going. After six
weeks
of failure, he
shot and killed the store owner.
I seem to recall an incident a few years ago when somebody reached round
the back of their PC to plug a mouse (I think) in and got a (fatal?)
electric shock.
I think the problem was that the computer chassis wasn't correctly
earthed (grounded) and was floating at about 65V due to the mains filter
components. The poor chap was grounded by touching something else, and
thus got a shock.
But an earth test should pick up such problems, and they appear to be
rare anyway.
-tony