26 May
2010
26 May
'10
11:41 a.m.
On 25/05/10 19:24, Tony Duell wrote:
In which case they deserve the Darwin Award. Although sticking your
fingers on a marked, live AC connector is probably not quite inventive
enough to get a DA.
I would agree...
As an aside, although I have never held a firearm, and never intend to,
one thing I was taught by somebody who used a shotgun was that 'All guns
are loaded unless _you_ have verified they are not'. In other words,
don't assume a gun is safe ebcuase somebody has said it is. I have
modified that into 'All connections are live until you've checked they
are not'. You don;t touch any metal part unless you have checked it is
not at a letahl voltage.
Unfortunately, aas Peter Turnbull implied, the HSE doesn't agree with me :-(
And then
of course there are the ever-present "Please do not touch" signs...
Whcih IMHO are useless. The clueful know not to stick their fingers in an
unknown machine, the clueless probably can'r read, or if they can't think
the sign doesn't apoply to them.
I'd probably run the machines in question off of RCD (aka GFCI,
PowerBreaker) adapters, just in case someone did find a live point that
Many of my machines have sufficientl;y large capacitors in the mains
filters that they trip such devices anyway...
They also will not protect you against high voltages on the secondary
side of an isolated PSU -- for example the voltages applied to cathode
ray tubes in most monitors. Admittedly the current there is unlikeky to
be lethal (I can give at least one counterexample, though), but...
wasn't covered up... ~10mA for the few
milliseconds it takes for a
PowerBreaker to trip is less likely to do lasting damage than the 5-6
seconds it'd take for me to get up, grab the mains plug and yank it out
of the socket (13A plugs tend to be quite stiff compared to, say, IECs,
and not all machines are fitted with IEC sockets).
Though if the idiot turned round and said "your machine electrocuted me"
I'd be quick to point out that:
1) If it had electrocuted them, they'd be dead
But what if the worst does happen?
2) There was a "Live parts, please don't
touch, danger of death,
etc." sign on the desk
And it's an small kid who can't read? Yes I know such people shouldn't be
running around a classic computer demonstration, which is one of my
reservations about having the VCF as an add-on to a puiblic museum.
3) The live parts were marked and covered, and that
pushing one's
finger around the cover to touch a live part of the machine wasn't an
especially smart idea
4) They'd be best advised to at least make an attempt to learn from
the experience and BLOODY WELL NOT DO IT AGAIN.
And then you find yourselkf on the wrong end of a lawsuit and/or doing a
battle with the unsurance company providing public liability cover. There
are better things to spend time and money on...
I do not suffer fools gladly.
I am sure you realise I don't either. :-)
-tony