These comments are clearly made by someone who has experience with this
matter!
Dick
-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: classiccmp_at_classiccmp.org <classiccmp_at_classiccmp.org>
Date: Monday, February 28, 2000 4:40 PM
Subject: Re: Is ringing voltage dangerous?
>>
>>
>> >RULE 1, unless the voltage is very low it _can_ be dangerous. Low is
hard
>> > number be exact about but, over 12-30V is the watch out zone.
>> >RULE 2, All efforts are to be made to avoid crossing the heart or chest
>> > as a possible path for safety. One hand in pocket rule is
derived
>> > from this.
>> >RULE 3, if you not sure, make sure. get a meter and find out if it's
live
>> > and how hot hot is.
>>
>>
>> I just want to add a rule - Don't always trust what the meter says. I
took
>
>I believe that when working on live power lines and other circuits
>carrying dangerous voltages, you test the meter on a known HV source,
>then you test the line, then you test the meter again on said known HV
>source. Then, normally, you connect the power line to earth, assuming
>it's shown to be dead. And only then do you touch it.
>
>Some HV meters used for this sort of thing have a 'proving unit' (a small
>PSU that gives out a few kV at a minimal current, running off batteries)
>in the carrying case for these tests.
>
>> 1950 v from an electron multiplier supply because the meter read around
40
>> volts. There was a common failure mode of this supply that it would shut
>> down to 40 v. Instead of walking around to shut it off before
>
>Ouch!. That's not pleasant :-(. Oh, and never trust indicator lamps (they
>can burn out), and never trust on/off switches to isolate something. Pull
>the mains plug and put it where you can see it (or some idiot will plug
>it in again).
>
>I'll add another 'rule'... When you are sure something is not live, brush
>it with the back of your finger. If, by some strange chance it _is_ still
>live, your finger will be thrown off. Touch it with the front of your
>finger and you'll be forced into better contact with it.
>
>-tony
>
Received on Mon Feb 28 2000 - 18:29:02 GMT