KB6NU's Ham Radio Blog

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Check your meter before measuring high voltage

Posted: 29 Nov 2017 05:08 PM PST
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A letter in the December 2017 QST caught my eye. It had a safety tip for
dealing with high voltage circuits, and I thought I would pass it along.
Its reprinted with permission from the author, Joseph Birsa, N3TTE..Dan


Reading the article on DMMs in the October 2017 issue of QST reminded me of
a safety practice I want to pass along. Always, always, ALWAYS check the
meter leads using the resistance function of a meter BEFORE checking a
hazardous voltage! (Or any voltage or current for that matter.)

To do this, BEFORE YOU DO ANYTHING ELSE, turn the meter to ohms and short
the tips of the leads to verify continuity (zero or low reading). Then,
switch the meter to the appropriate function and proceed.

When I was starting out as an electrical engineer, a field engineer, who
was a ham by the way, told me a story about an electrician who opened an
equipment cabinet powered by three-phase, 480 V. Before beginning, he used
his meter to check the 480 V. Seeing no voltage, he proceeded and was
subsequently electrocuted! When they checked his meter, they found one of
the leads was opened. Or perhaps a fuse was blown.

Since then, the first thing I do when I start to use a meter is to use the
resistance function to check lead continuity.

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