Health, Safety, and Environmental Practice
Electrical safety practice centres on the hierarchy of risk control: eliminate, substitute, engineer controls, administrate, and finally use PPE. Understand that PPE is the last line of defence, not the first. Know the safe-isolation procedure: identify, isolate, lock off/tag, prove dead (test), and earth or discharge where required - and re-prove the tester before and after.
Understand the hazards: electric shock (current through the body), arc flash (thermal and pressure effects), and stored energy. Know the meaning of live working versus dead working, and that live work requires justification and a permit. Understand lockout/tagout, permits to work, and the role of the authorised person.
Environmental practice covers handling of insulating oils, SF6 gas (a potent greenhouse gas), batteries, and electronic waste, plus spill response and disposal routes. Know that SF6 must be recovered, not vented.
Worked rule of thumb: The safe-isolation sequence is often remembered as "identify, isolate, lock, prove dead, earth." Prove the voltage tester on a known live source before and after testing the isolated conductor - a tester that fails silently is a lethal trap.
Traps: treating PPE as the primary control; skipping the re-prove step; and assuming a circuit is dead because a switch is off - always prove dead at the point of work.