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Page IV
Safety and Hazard Awareness
Troubleshooting and Servicing HVACR Electrical Systems
DO NOT WORK ALONE
If you must test a live circuit, have someone with you ready to turn off the power, call for help, or give
cardiopulmonary resuscitaƟon (CPR).
LEARN FIRST AID
Anyone working on electrical equipment should take the Ɵme to learn CPR and first aid.
ELECTRICAL BURNS
Do not wear rings or other jewelry when working on live electrical circuits. A wristwatch that comes
in contact with a live terminal can cause a shock or a severe burn. Never use screwdrivers or other
conducƟve tools in an electrical panel when the power is on. If you were to slip and complete a
circuit to ground, a tremendous amount of current would flow, possibly resulƟng in electrocuƟon.
Remember Ohm’s Law? If you are working on a 120‐V circuit and create a short to ground with a
screwdriver blade that has a resistance of 1 ohm, then 120 amps of current will flow. Rings, jewelry,
screwdriver blades, etc., generally have resistance values of much less than one ohm.
PORTABLE ELECTRIC TOOLS
Portable electric tools constructed with a metal frame should have a grounding wire in the power
cord. The grounding wire protects the operator from electrical shock if the tool develops a loose
connecƟon that could cause the frame to become hot. If this occurs, the grounding wire, not your
body, will carry the current to ground, and a breaker or fuse will interrupt the circuit. In some
instances, wall receptacles with two prongs may be adapted to a three‐prong cord. The adapter has a
ground wire that must be connected to a good ground in order for the circuit to provide protecƟon.
More modern receptacles have a Ground Fault Circuit Interrupter (GFCI) design. A GFCI receptacle
can detect a very small electrical leak to ground, and will open the circuit to prevent further current
flow.
It is a good safety pracƟce for service personnel to have a short extension cord with a GFCI receptacle
for field use of power tools and equipment.
Many modern handheld power tools are constructed with their wiring and motor housed in a plasƟc
case and are considered double insulated. BaƩery operated tools use rechargeable baƩeries, which
are both convenient and safe.