Workplace Safety
Workplace Safety - what the exam tests
The Workplace Safety domain checks whether you can set up and control an automotive electrical job so nobody gets hurt: battery handling, high-current short circuits, fire, acid, exhaust gas, lifting and housekeeping. Questions are scenario-based, not definitions.
Electrical and battery hazards
- Disconnect the battery negative terminal first and reconnect it last. This keeps the wrench away from the body shell if it slips and keeps sparks away from fuel vapour.
- 12 V is not dangerous by voltage, but a battery can deliver several hundred amps into a short. A ring or watch strap across a terminal glows red in under a second - remove jewellery.
- Insulate the disconnected terminal; never leave a live positive cable loose near the body.
- On vehicles with airbags (SRS), wait the manufacturer's stated time, often 1–3 minutes, after disconnection before working near modules.
Chemical, fire and fume hazards
- Lead-acid electrolyte is dilute sulfuric acid. Wear goggles and acid-resistant gloves; flush eyes for 15 minutes after contact.
- Neutralise spills with sodium bicarbonate - not with a strong alkali.
- Charging releases hydrogen, explosive between about 4% and 75% in air: ventilate, no sparks, no smoking.
- Electrical fires: CO₂ or dry powder, never water on live equipment.
- Run engines outdoors or duct the exhaust away; carbon monoxide is odourless.
Lifting and housekeeping
Chock the wheels, support on jack stands rather than the jack alone, keep the floor dry and clear, and store batteries upright on a non-conductive rack.
Worked example
A technician removes a starter with the battery still connected. The ring spanner bridges the starter B+ stud and the engine block: a dead short of hundreds of amps, a welded spanner and a battery that may burst. Correct sequence: chock, disconnect negative, insulate the terminal, then undo B+ at the starter. Reasoning: breaking the ground side first means any accidental contact on the live side has no return path.
Traps that cost marks
- Saying "disconnect the positive first".
- Treating 12 V as harmless.
- Water on an electrical fire.
- Working under a car held only by a hydraulic jack.