In this module
Objectives covered: LO 3.5.1. By the end you will be able to:
- Explain how electric shock, burns, arc flash and fires happen.
- Describe grounding, GFCI/RCD protection and safe wiring practices.
- Know who may work on electrical equipment and the approach rules.
5.1 How electricity hurts people
Current flows when the body becomes part of a circuit. As little as 50 to 100 milliamps across the chest can stop the heart. Electricity also causes burns, arc flash (an explosion of heat and light up to 20,000 °C), falls after a shock, and fires from overloaded or damaged wiring.
5.2 Main protections
- Insulation: undamaged cords and cables; no taped or spliced flexible cords.
- Guarding: live parts over 50 V enclosed; panel covers and blank fillers in place.
- Grounding (earthing): a low-resistance path so faults trip the breaker.
- GFCI / RCD (ELCB): trips at about 5 to 30 mA leakage, fast enough to prevent electrocution. Required in wet locations and for temporary power.
- Overcurrent protection: correct breakers and fuses, never bypassed.
- Clearance: keep at least 3 feet (0.9 m) clear in front of panels; never block them with stock.
5.3 Qualified and unqualified persons
Only qualified persons, trained on the equipment and its hazards, may work on or near exposed live parts. Unqualified persons must keep at least 10 feet (3 m) from overhead lines up to 50 kV. Work should be done de-energised with lockout/tagout unless de-energising creates a greater hazard; live work needs an energised work permit and arc-rated PPE.
- 29 CFR 1910 Subpart S (1910.301 to 1910.399): electrical design and safe work practices (1910.331 to 1910.335).
- NFPA 70E: electrical safety in the workplace, arc flash risk assessment.
- Bangladesh: Bangladesh Electricity Act 2018, BNBC 2020 Part 8 (electrical), and licensed electricians.
Electrical faults are a leading cause of factory fires in Bangladesh. Accord inspections found overloaded distribution boards, missing earthing and cables run without conduit in many factories. One knitting factory in Narayanganj added RCDs on all socket circuits, thermographic scanning of panels every six months, and a rule that only licensed electricians open panels. Its electrical incidents dropped to zero.
Learning Check
Answer these two questions to check your understanding. You can try again as many times as you like.