On 13/07/2015 07:22, John G wrote:
Phil Allison has brought this to us :
Ralph Mowery wrote:


That should be done with any piece of equipment. Practice with it
and learn the odd things about them.

** As Clint Eastwood might have said: " a man's gootta know the
limitations of his test gear ... "


Where I worked there were many wires in a conduit carring 120 volt
control voltage. With a digital meter there was so much induced
voltage you could not tell if a wire was really active or not. You
had to put some kind of a load on them. YOu could take an analog
meter and start with a high voltage range and then switch to a lower
range. If the meter stayed in the same or near the same physical
position, it was just showing the induced voltage.
Even with a wire disconnected at each end,it would still shock the
crap out of you due to that voltage.


** Electricians once regularly used 40W bulbs in a protected, hand
held fittings to test if circuits were live - see pic.

https://img1.etsystatic.com/068/0/63...18127_nbxf.jpg

The AC plug was replaced with two probes in the examples I saw.

I guess it was important to test the bulb before each use ...


... Phil


Some used 2 bulbs in paper bakelite tubes wired in series then they
could test line to line or line to neutral with the same device without
worrying about the voltage or about spurious couplings of mythical
voltages like you can get with meters especially Digital meters.

Once in college Elec Eng Lab, a cotractor wanted to test 3 wires, rubbed
2 together and closed down whole large building. when asked our
instructor agreed that was not the accepted method. :-?


Is it apochriphal? . I was told that civil engineering subcontractors,
laying new utilities water/sewage/electricity etc in trenches, would
confirm that any power cables they came across that should be dead ,
were dead or not.
Using a cartridge powered cutting blade , that was explosively shot
across the cable, severing it.