I've seen similar results of destroyed consumer grade DMMs which were being
used used in an industrial environment.
The cases and probes were nearly covered with vaporized metal residue.

In the instance of a RShack meter, I dunno what the user was trying to do,
but the shadows of his fingers could be seen on the meter case and probes.
He survived the incident but could've been killed since he was inside an
electrical closet lined with live, exposed buss bars.

Only properly designed industrial rated DMMs are capable of surviving
Oh****! mistakes in industrial equipment.

The proper spacing of board traces and component orientation are fairly
critical at elevated voltage levels, especially when the high current
capacity of industrial circuits can easily vaporize almost anything that
approaches the breakdown/arc-over threshold.

The resulting plasma effect immediately fills the surrounding air with a
cloud of metal, increasing the likelyhood of more breakdown events in the
same vicinity.

The presence of a small glass fuse in a DMM or other test equipment doesn't
mean the user is safe from similar events.

--
Cheers,
WB
..............


"William Sommerwerck" wrote in message
...
You'll like this. (For those easily offended, these Ozians drop a few S
bombs.) Watch all of it. The demo with the aluminum block is surprising.

http://hackaday.com/2010/05/05/when-multimeters-go-boom

I once asked a Fluke engineer why their DVMs were so expensive. He said
most
of the cost was in protecting the unit from misconnection or high
voltages.

I wish Greg Lefebvre were alive to see this. I can hear his raucous
laughter. "Oh, Willie..."

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land