General
Information
1-5
Safety Guidelines
for
High-Voltage Testing
Here
is
a list of safety gUidelines to
be
followed when working with voltages
in
excess of
SOV
dc or
SOV
ac root-mean-square (RMS).
1.
Know each step of the test procedure. Check the test setup to
be
sure the instruments are
connected properly
and
that
all
control settings are correct.
2.
Never defeat interlocks.
3.
Never have
one
hand
on
chassis or other ground while measuring high voltages with a
probe
held in the other hand. Use the
one-hand
method, that
is,
probe
in
one
hand, the other
hand
behind the back or
in
a pocket.
4.
Make sure the probe being used has voltage insulation higher than the voltage being mea-
sured. Check wires
and
probes for cracked insulation
and
defects. If any defects are
noted
do
not use until repairs are made.
S.
Make certain that the instrument to
be
serviced
is
turned off
and
all
capacitors
and
high-
voltage circuits are discharged before any component or hardware
is
removed or touched.
Remember that a circuit can
be
lethally charged
if
a component
is
open
or missing,
or
if
a
wire
is
disconnected or open, even with the ac power switch
off.
Isolated heat sinks can also
be
statically charged.
6. Make certain that instruments used for testing are used within their rated specification. Never
use instruments floated above their specified rating.
7.
Never reach
around
energized high-voltage circuits. Always turn equipment off
and
dis-
charge the high voltage
first.
8. NEVER WORK ALONE. Be familiar with location of power switches
in
your area
and
what
they control. Turn off power to free a fellow worker from high voltage without energizing
yourself.
9. Keep work area neat, free of any interfacing conductive material,
and
free of
any
sharp
objects. Remember, a reaction to a shock can cause
one
to strike nearby objects which can
result in a serious injury.
10. Always leave safety shields in place unless work must
be
done
on
circuits behind the shields.
11. Never leave work area with high-voltage equipment energized
and
high-voltage circuits
exposed.
12. Have available
and
use approved warning signs
and
tags where high-voltage testing
is
in
process.
13. Do not make measurements
in
a circuit where a corona
is
present.
Corona
can
be
identified
by a pale-blue color, from a buzzing sound emanating from sharp metal points
in
the circuit,
or
from the
odor
of ozone.
14. Hands, shoes, floor,
and
workbench must
be
dry. Avoid making measurements
under
humid, damp, or other environmental conditions that could affect the dielectric-withstanding
voltage of the test leads
or
instruments.
IS.
All
test procedures
and
safety procedures should
be
strictly followed at
all
times.
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