Safety at Work, Electrical Hazards, and First Aid
Safety at work, electrical hazards and first aid tests judgement as much as memory: recognising the hazard, isolating correctly, and acting properly in the first minutes after a shock.
Controlling the hazard
- Isolate, lock off and tag. Prove dead with a tester that has been proved on a known live source both before and after the test; discharge capacitors and earth where required.
- Work de-energised by default. Live work needs a written justification, a second person and insulated tools.
- PPE: arc-rated clothing for switching, insulating gloves, face shield and safety footwear. Arc-flash energy depends on fault level and clearing time.
- Wet, dusty, confined and metallic locations raise shock risk; SELV and 30 mA RCDs are the standard mitigations.
Physiological thresholds
- About 1 mA is perception; 10–15 mA is the let-go threshold; 30 mA can cause ventricular fibrillation with prolonged contact. Body resistance collapses with wet skin and higher voltage.
Worked example - first aid
A worker is gripping a live conductor and cannot let go. Do not touch the casualty. Switch off at the nearest isolator; if that is impossible, free the person with a dry insulating object while standing on dry insulation. Call 101 (Magen David Adom) and begin CPR at 30 compressions to 2 breaths; attach an AED as soon as it arrives and follow its prompts. Treat electrical burns as deep burns and always obtain medical assessment, because arrhythmia can appear hours later.
Traps
- Pulling the casualty away by hand and becoming a second victim.
- Switching off but not proving dead before touching the conductor.
- Delaying compressions while searching for a pulse.
- Applying water or ointments to an electrical burn.