Electrical Safety

Overview

Shock and arc flash dominate — de-energize and prove dead; live work only as a last resort.

Safe isolation — 'test before touch'

De-energize and apply LOTO at the supply.
Prove the tester on a known live source.
Test all conductors to confirm dead.
Re-prove the tester.
Apply portable earths where required.

Key controls

Only qualified, authorized personnel.
Insulated tools and arc-rated PPE near live parts.
Maintain safe approach distances; barrier live panels.
Functional RCD protection on temporary supplies.

Roles & responsibilities

Role	Responsibility
Authorized electrical person	Performs isolation, testing and the work.
Supervisor	Confirms competency, permit and isolation.
Other trades	Keep clear of electrical work areas.

Common mistakes to avoid

Assuming dead without testing.
Using an unproven tester.
Working live for convenience.

Legal requirements (Thailand)

Occupational Safety, Health and Environment Act B.E. 2554 (2011) — the governing workplace-safety law in Thailand.
Ministerial Regulation on OSH for electrical work B.E. 2558 (2015).

Frequently asked questions

What is Electrical Safety?

Two hazards dominate electrical work: electric shock (current through the body) and arc flash (an explosive release of energy from a short circuit, with intense heat and pressure). The safest state is de-energized and proven dead. Live work is only ever done when de-energizing is genuinely impractical, by a qualified person with arc-rated PPE.

Who is responsible?

Authorized electrical person: Performs isolation, testing and the electrical work.; Supervisor: Confirms competency, permit and isolation before work.; Other trades: Keep clear of isolated/live electrical work areas.

What are the most common mistakes to avoid?

Assuming a circuit is dead without testing — always test before touch. Using a tester that hasn't been proven before and after. Working live for convenience when isolation was possible.

References — Company procedure; safe-isolation practice; IEC 60364; Thai OSH Act B.E. 2554.