Occupational Health, Safety and Environment (Electrical Safety)
What the domain tests
This domain covers electrical safety at the workplace: recognising shock and arc hazards, isolating equipment, using PPE, and responding to accidents without making them worse. It also tests environmental housekeeping and basic first aid.
Core rules
- Treat all conductors as live until isolated, tested and proved dead. Use lockout/tagout and keep the key with the person working.
- The danger from shock depends on current, path and duration: roughly 1 mA is perceptible, 10–30 mA can cause muscle contraction, and 50 mA or more across the heart can be fatal. Voltage drives the current, but body resistance and contact conditions matter.
- Use insulated tools, rubber gloves, safety shoes and arc-rated clothing as the task demands; inspect before use.
- Earth metallic enclosures; never rely on gloves alone for protection.
- For electrical fires, isolate the supply and use CO₂ or dry powder, not water.
- Rescue: switch off, call for help, give CPR if trained, and do not touch a casualty still in contact with live parts.
Worked example
A worker contacts a 230 V conductor while sweaty, with an estimated body resistance of 1,000 Ω. Using I = V/R, I = 230/1,000 = 0.23 A = 230 mA. That current is far above the let-go threshold and can cause ventricular fibrillation, so immediate isolation and emergency response are required. The calculation shows why dry conditions, insulation and RCD protection matter.
Traps
Do not say “low voltage cannot kill”-230 V can. Do not throw water on an electrical fire. Do not assume a rubber glove is tested insulation; gloves must be rated, inspected and tested. Do not restart a tripped circuit before finding the fault.