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_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, August 22, 2000 12:50 PM
Subject: Re: Lethal computers? (was: Goodwill Computerworks Museum is open
> >
> > 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
paid
> > 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
>
>
Received on Tue Aug 22 2000 - 18:18:08 BST