On Thu, Jan 22, 2009, 7:51pm email@example.com (Arlowe) wrote:
krw explained on 21/01/2009 :
this immortal opus:
krw used his keyboard to write :
krw explained on 19/01/2009 :
on 16/01/2009, Paul supposed :
I'm testing a new DMM I purchased, AM-240 by Amprobe. It claims *over*
100Mohm impedance in 400.0mV mode.
Nothing new there, many DMM's have selectable "high impedance" or "HI-Z"
modes on the mV range. e.g. the Fluke 87.
I've looked at the specs of ~ 30 DMM's today, include a lot of fluke's,
and never seen anything near 14Gohms impedance. Keithley has an
electrometer that's probably higher. Most DMM's are around 10Mohms (not
gigaohms) input impedance. Don't you think 14 gigaohms is a bit high?
The evil thing about Voltmeters with very high impedance is they will
read induced voltages that analog meters wouldn't. It makes a voltmeter
useless for checking for live circuits in a crowded panel.
A craftsman never blames tools for his failures. Hackers, on the other
If you work with electricity you had better know the limitations of your
tools or you will find them...the hard way.
That is certainly true (though perhaps your heirs are the ones who will
find you), but doesn't modify my statement. In this case, the tool *can*
be used as long as the one using it knows what he's doing.
Ok....everything seems to pass right over your head.... I pointed out a
limitation of a DMM and you seem to be inferring that I am somehow a
hack who blames his tools... BTW> I am not a "craftsman" I am an
electrcian.. You don't do what I do for as many years as I have without
knowing what the fuck you are doing.
What's wrong with using a hi Z voltmeter in a live panel? I do it more
often than I really care for, and never have a problem.
There isn't anything wrong with it. Analog meters are dead. High
impedance digital meters are only a problem if there is a loose nut
inside the panel, holding the leads.
I don't test for live circuits with a DMM. I use test lamps or a low(er)
impedance voltmeter. If you worked for me I would sack your arse if I
caught you using a DMM to test for live.
=>Arlowe: Ye shouldest cover thine arse and prepareth for a loss if mine
DMM, openend Ammeter would causeth thee to derecruit me., there is no
law or work code regulation violated by testing a live circuit with the
proper test equipment and procedure...some DMMs' come with a clip on
carrying case to facilitate it being attached to chassis bodies etc. for
hands free testing.I wouldnst' work for thee anyway, Troll.
The Mighty WontVolt