Instruction manual
Section 1 - Test Instrument Safety
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 volt-
age 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 cer-
tain 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 precaution.
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 volt-
age 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 equip-
ment 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. This includes most recent television receivers and audio equipment. A
plastic wooden cabinet insulates the chassis to protect the customer. When the cabinet is re-
moved 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 1604A Isolation Transformer or Model 1653A or 1655A 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.
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