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Section 1
Safety Guidelines
WARNING
Normal use of test equipment exposes you to a certain amount of danger from electrical shock because
testing must sometimes 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. A voltage as low as 35
volts DC or AC (RMS) should be considered dangerous and hazardous since it 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 to
prevent contact with exposed high voltage and to steer current away from your heart in case of
accidental contact with high voltage. You will significantly reduce the risk factor if you know and
observe the following safety precautions.
1. Don’t expose high voltage 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.
2. 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.
3. Use an insulated floor material or a large, insulated floor to stand on and an insulated work surface
on which to place equipment and make certain such surfaces are not damp or wet.
4. 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.
5. 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. any time the equipment
is connected to an AC outlet, even if the equipment is turned off.
6. Some equipment with a two-wire AC power cord, including some with polarized power plugs, is the
“hot chassis” type. A plastic wooden cabinet insulates the chassis to protect the customer. When the
cabinet is removed for servicing, a serious shock hazard exists if the chassis is touched. Not only
does this present a dangerous shock hazard, but damage to test equipment. Always connect an
isolation transformer between the AC outlet and the equipment under test. The B&K Precision
Model TR-110 or 1604 Isolation Transformer or Model 1653 or 1655 AC Power Supply is suitable
for most applications. To be on the safe side, treat all two-wire AC equipment as “hot chassis”
unless you are sure it is isolated chassis or an earth ground chassis.
7. On test instruments or any equipment with a 3-wire AC power plug, use only a 3-wire outlet. This is
a safety feature to keep the housing or other exposed elements at earth ground.
8. B&K Precision products are not authorized for use in any application involving direct contact
between our product and the human body or for use as a critical component in a life support device
or system. Here “direct contact” refers to any connection from or to our equipment via any cabling
or switching means. A “critical component” is any component of a life support device or system
whose failure to perform can be reasonably expected to cause failure of that device or system or to
affect its safety or effectiveness.
Never work all alone. Someone should be nearby to render aid if necessary. Training in CPR (cardio-
pulmonary resuscitation) first aid is highly recommended.
