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3 Safety Issues
Normal use of equipment exposes users to a certain amount of danger from
electrical shock because testing must be performed where exposed voltage is
present. An electrical shock causing 10 milliamps of current to pass through the
heart will stop most human heartbeats. Voltages as low as 35 V (DC or RMS
AC) should also be considered dangerous and hazardous since they can
produce a lethal current under certain conditions. Higher voltages pose an even
greater threat because such voltage can more easily produce a lethal current.
Your normal work habits should include all accepted practices that will prevent
contact with exposed high voltage, and those that will steer current away from
your heart in case of accidental contact with a high voltage. You will significantly
reduce the risk factor if you know and observe the following safety precautions:
•
If possible, familiarize yourself with the equipment being tested and the
location of its high-voltage points. However, remember that high voltage
may appear at unexpected points in defective equipment.
•
Do not expose high voltage components needlessly. Remove housings
and covers only when necessary. Turn off equipment while making test
connections in high-voltage circuits. Discharge high-voltage capacitors
after removing power.
•
Use an insulated floor material or a large, insulated floor mat to stand on,
and an insulated work surface on which to place equipment. Make certain
such surfaces are not damp or wet.
•
Use the time-proven “one hand in the pocket” technique while handling an
instrument probe. Be particularly careful to avoid contacting a nearby
metal object that could provide a good ground return path.
•
When testing AC powered equipment, remember that AC line voltage is
usually present on some power input circuits, such as the on-off switch,
fuses, power transformer etc., and any time the equipment is connected to
an AC outlet, even if the equipment is turned off.
•
Never work alone. Someone should always be nearby to render aid if
necessary. Training in CPR first aid is highly recommended.
