> Yesterday, a minister was standing in a baptismal tub at a
> church in Waco, Texas, reached out and touched a microphone
> and was electrocuted.
Never a good idea to touch anything electrical while standing
in water. Especially a baptismal tub.
> QUESTION: An XLR microphone is fed by a positive, negative,
> and ground connection.
Not quite right. Positive and negative refer to polarity of
a direct current source. With microphones the + and -
refer to the high and low sides of audio.
> Assuming the microphone was working,
> could this suggest that the ground was not connected?
It more strongly suggests that the ground (shield and,
perhaps an additional drain wire) WERE connected. But
read on and weep!
> If
> not the microphone itself, could a ground missing in the
> console or amp have led to this?
In this kind of instance it is most typical that either the
amplifier was pretty old and didn't have a 3-prong (U-ground)
AC cord; that somebody has cut off the ground prong or that
the AC system into which it was plugged was faulty or,
perhaps very old, and lacking a ground connection.
Older amps sometimes had one side of the AC cord connected
directly to the chassis and the plugs were polarized (one
prong wider than the other) so the chassis would always
be connected to the neutral. Unfortunately, easily defeated
by accident or by changing a worn-out plug, etc. There are
many ways the hot side of the AC line might have gotten
shorted to the microphone ground (shield) with predictable
results.
Understand, I'm not trying to guess what caused this particular
accident; commenting only on how this KIND of thing happens.
> Given an industry that puts microphones (sometimes hastily)
> in a variety of envirionments, especially outdoor remotes,
> how do we protect ourselves from grabbing a lethal mic?
First, by not defeating the grounding of any equipment through
cutting off the third prong on the AC cord or by using a 3 to
2 prong adapter (these have a ground wire you're supposed to
attach to earth ground, intended for use when the electrical system
is old and doesn't have a ground pin on the socket).
Second, by checking with a volt meter between the microphone shell
and the U-ground socket on the wall plug to make sure there's nothing
going on.
Third, by never handling anything electrical while standing in
water or even on wet ground. I've always made it a practice
to wrap the "handle" of any mic to be used outdoors in a couple
of layers of electical tape. Even including the metal of the
XLR. And that's not intended to be primary protection; rather
to protect against something that breaks down or otherwise goes
wrong after checking the equipment first.
Of course you can be a little less "picky" if the equipment is
entirely battery operated like a portable recorder or camera.
The faith of one who touches a microphone while standing in a
pool impresses me! The intelligence? No, But the faith!!!!
Even with all this stuff some experienced engineers manage to
kill themselves each year by defeating interlocks and raising
ENG vehicle masts into powerlines.
<P ID="signature">______________
"Only sick music makes money today."
--Friedrich Nietzsch (he said this before
rap was invented, or even rock!)</P>
