Workplace Safety, Electrical Safety and Environmental Practices
Safety questions test whether you can identify a hazard, choose a control, and handle waste responsibly. The exam expects practical rules, not general slogans.
Core facts
- Electric shock depends on current path, duration, and current level. A few tens of milliamperes through the chest can be dangerous; 230 V across about 1 kΩ of body resistance would drive roughly 230 mA.
- Protection includes insulation, earthing, MCB/RCD, fuses, isolation, and lockout. An RCD detects earth leakage and trips at a set residual current.
- Use insulated tools, remove jewellery, avoid wet hands, and discharge capacitors before servicing.
- E-waste contains lead, mercury, cadmium, and brominated flame retardants. It must go to authorised recyclers, not ordinary bins or open burning.
Worked example
A technician touches a 230 V live conductor while standing on a damp floor. If body resistance is about 1000 Ω, I = V/R = 230/1000 = 0.23 A = 230 mA. This is far above the 30 mA trip level of a typical RCD, so the RCD should disconnect quickly. The calculation shows why earthing and RCD protection matter: the current is limited mainly by resistance, not by the voltage label alone.
Traps
- Treating low-voltage circuits as automatically safe; charged capacitors can still bite.
- Working live when isolation is possible.
- Putting lithium cells or circuit boards in household waste.
- Assuming a fuse protects a person; it mainly protects wiring and equipment.