I'm still confused as to why testing with a multimeter is dangerous when live checks are done before and after.......
It's not you. Provided one does the before and after proving checks, I can think of no rational engineeering reason (even taking into account the possibility of human errors such as having the meter on an inappropriate range) why use of a multimeter should be any more dangerous than a test lamp - even if the rules, regulations and guidelines don't accept that.I'm still confused as to why testing with a multimeter is dangerous when live checks are done before and after.......
a multimeter should NOT be used to prove a circuit is live or dead.
Because?
That's only a danger if you don't do it properly - i.e. prove the meter both before and after your test.On all H and S courses your told that, it is too easy for the meter to be on the wrong setting and the user getting a wrong reading
a multimeter should NOT be used to prove a circuit is live or dead.
Because?
On all H and S courses your told that, it is too easy for the meter to be on the wrong setting and the user getting a wrong reading
Exactly. I can't think of anything else that would do that, either. More to the point, no matter what range the meter was on, if (for whatever reason) it gave an indication of about 230 when known 230V AC was applied to it before and after the test, but indicated no voltage during the test, I'd be quite happy that the circuit tested was dead.I don't buy the mantra of 'the course said this so I don't do it that way' for the course to say that they must have some justification. If it's the for the wrong scale I accept but if I'm testing for live before hand I'm looking for a a 230ish reading...and I can't think of anything that would give that reading on the wrong gauge....
Indeed - but, as I said, one should not blame the tools for the actions of dangerous work(wo)men.To be honest ive seen many engineers test for dead wrongly, by not testing or proving first, i think its more aimed at them people.
For anyone reading who may be interested http://www.hse.gov.uk/pubns/priced/gs38.pdf[/QUOTE]
Thanks. I've just had a quick read through and virtually of it is essentially very good common sense - most of which one would hope those using electrical test equipment would not really need to be told - but it does no harm to have it written down!
In the context of this thread, I note with interest that what is actually says about 'testing for dead' is:
... which seems appreciably weaker than the 'thou shalt not use multimeters' line that has been asserted in this thread! It easily could say "don't use multimeters", but it doesn't.to establish the presence or absence of voltage, the preferred method is to use a proprietary test lamp or 2-pole voltage detector suitable for the working voltage of the system rather than a multimeter.
Kind Regards, John.
next with the back of the forefinger to make sure - dead as expected.
I'm still confused as to why testing with a multimeter is dangerous when live checks are done before and after.......
I'd also try and start the machine afterwards to ensure the isolation as contactors will show the 3 phase to the motor as dead even if the supply fuses are fitted and isolator on.i disagree.
If im isolating a manufacturing vessel to allow a mechanical engineer to enter the vessel and remove a disc dissolver, and i dont use the correct equipment to check the circuit for dead i am leaving myself wide open for prosecution if that dissolver was infact still live and was started by some unsuspecting operator. Against a dissolver you stand no chance of survival - 95 Kw of 3 phase motor with a 14 inch cutting disc on the end of the shaft.
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