Electrical Safety
for HVAC Technicians

Why Electrical Safety Matters

Electrocution is one of construction's "Fatal Four" - the four leading causes of worker deaths. HVAC technicians work daily with 120V, 240V, and 480V systems. Understanding electrical hazards and safe work practices is not optional - it is the difference between going home and not.

The four main electrical hazards are: shock (current through the body), arc flash (explosive electrical release), arc blast (pressure wave from arc flash), and fire (from overloaded circuits or faults).

Effects of Electrical Current on the Body

Current Level	Effect on Body
1 mA	Barely perceptible
5 mA	Slight shock, not painful, person can let go
6-30 mA	Painful shock, loss of muscle control - cannot release conductor
50-150 mA	Extreme pain, respiratory arrest, possible ventricular fibrillation (heart attack)
1,000-4,300 mA (1-4.3A)	Ventricular fibrillation, severe burns, death likely
10,000 mA (10A)	Cardiac standstill, severe burns, death probable

? 100 Milliamps Can Kill

The standard 15-amp household circuit breaker protects equipment, not people. It takes only 100 milliamps (0.1 amps) - 150 times less than the breaker trips at - to cause cardiac arrest. Breakers do not protect against electrocution.

Ground Fault Circuit Interrupters (GFCI)

GFCIs detect current imbalances as small as 5 milliamps and trip within 1/40th of a second - fast enough to prevent electrocution. OSHA requires GFCI protection for all 120V, single-phase, 15 and 20 amp circuits on construction sites.

GFCI Type	Where Used	HVAC Application
GFCI receptacle outlet	Replaces standard outlet	Wet areas, garage, outdoor outlets
GFCI circuit breaker	Main electrical panel	Protects entire branch circuit
Portable GFCI adapter	Plugs in to provide protection	Extension cords, temporary power on job sites

Lockout/Tagout (LOTO) - 29 CFR 1910.147

Lockout/Tagout prevents the unexpected energization of equipment during service. It is required whenever a technician performs work that exposes them to unexpected startup or release of stored energy (electrical, hydraulic, pneumatic, thermal, gravitational).

The Six Steps of LOTO

Notify - Inform all affected employees that LOTO will be applied
Identify energy sources - Locate all electrical disconnects, breakers, and other energy sources
Shut down - Turn off equipment using normal stopping procedure
Isolate - Open the disconnect or breaker to isolate the energy source
Lock and tag - Apply your personal padlock and warning tag to the disconnect. Each technician applies their OWN lock
Verify - Try to start the equipment (should not start), then use a voltmeter to verify no voltage is present before touching any conductors

? Tagout vs Lockout

Lockout (using a physical lock) is always preferred over tagout alone. Tags are used only when the equipment cannot be locked out - they are a warning, not a physical barrier. When only a tag is used, additional protective measures must be taken because tags can be removed, ignored, or misread.

Safe Electrical Work Practices

Test before you touch - Always verify a circuit is de-energized with a properly calibrated voltmeter before touching conductors. Never assume.
One-hand rule - When working near energized circuits, keep one hand behind your back or in your pocket to prevent current from crossing your chest and heart
Insulated tools - Use tools rated for the voltage you are working near (1000V rated tools for most HVAC work)
Rubber insulating gloves - Wear appropriate class gloves when there is risk of contact with energized conductors
Dry surfaces - Never work on or near energized equipment while standing in water or on wet surfaces
Never bypass safeties - Do not bypass fuses, circuit breakers, or safety devices except as a temporary diagnostic step with you present

? Module 1 Module 3: Fall Protection ?