Electrical Safety

What is the primary hazard of electricity?

• AOnly the smell
• BElectric shock causing injury or death✓
• COnly the color
• DMaking noise

Answer: Electric shock is the primary hazard. Electricity can cause cardiac arrhythmia, respiratory paralysis, burns, and death. Even low voltages can be lethal under certain conditions.

What is the 'safe voltage limit' for 50V AC in the UK?

• AAnything below 50V is safe
• BAbove 50V AC becomes hazardous; lower voltages are safer but not necessarily safe✓
• C50V is never dangerous
• DOnly very high voltages are dangerous

Answer: While 50V AC is generally safer than higher voltages, it can still cause electric shock under certain conditions (wet conditions, contact area, individual factors). BS 7671 recommends extra-low voltage for certain situations.

What are the main routes of electrical current entry to the body?

• AOnly through the skin
• BContact with live parts; hand-to-hand, hand-to-foot, or foot-to-foot paths✓
• COnly the eyes
• DOnly through cuts

Answer: Current enters through contact with live parts, with dangerous paths including: hand-to-hand (across the chest, affecting heart), hand-to-foot, and foot-to-foot paths.

What is an 'arc flash'?

• ALightning in the sky
• BDangerous electrical event with intense heat and light from arcing between live conductors✓
• CA regular spark
• DA safety device

Answer: Arc flash is a dangerous electrical event where current jumps across a gap (arc), producing intense heat (>3000°C), light, pressure, and hot metal spray that can cause severe burns.

What does 'earthing' do in an electrical system?

• AMakes electricity work
• BProvides a return path for fault current and reduces electric shock risk✓
• CStops electricity
• DOnly for lightning

Answer: Earthing (grounding) provides a safe path for fault currents to earth, reducing the voltage experienced by a person in contact with an energized object.

What is 'double insulation' in electrical equipment?

• ATwo sets of wires
• BTwo layers of insulation preventing contact with live parts✓
• CUsing two plugs
• DExtra heavy cables

Answer: Double insulation provides two independent layers of insulation (functional and protective) so that if one breaks down, the second prevents contact with live parts.

What is a Residual Current Device (RCD)?

• AA type of wire
• BA safety device that detects current imbalance and disconnects the circuit quickly✓
• CA resistor
• DAn insulator

Answer: An RCD (earth leakage breaker) detects any imbalance between live and neutral currents (indicating current to earth) and trips the circuit within milliseconds, preventing serious shock.

What is BS 7671?

• AA cable type
• BThe IET Wiring Regulations - UK standard for safe electrical installation design and installation✓
• CA voltage rating
• DAn electrical component

Answer: BS 7671:2018 (Requirements for Electrical Installations) is the UK standard for the design, selection, installation, inspection and testing of electrical systems.

What does 'isolation' mean in electrical safety?

• ATurning off the lights
• BSeparating equipment from live parts by creating a physical barrier or disconnecting from supply✓
• CJust switching off
• DUnplugging a device

Answer: Isolation is the safe separation of electrical equipment from all live parts by physical isolation (barriers, covers) and/or electrical isolation (disconnection from the supply).

What is 'lock off tag out' (LOTO)?

• ALocking equipment in storage
• BProcedure of isolating equipment and preventing accidental energization by locking disconnects and applying warning tags✓
• COnly for padlocks
• DJust a label

Answer: LOTO involves isolating equipment from energy sources and using physical locks and warning tags to prevent unexpected startup while work is being carried out.

What should be done before working on electrical equipment?

• AJust dive in
• BIsolate from supply, lock off, test the circuit is de-energized, use appropriate PPE✓
• COnly if in a hurry
• DAsk someone else first

Answer: Safe procedure: Isolate the equipment, lock and tag the isolator, test with a voltage tester to confirm de-energization, and only then proceed with work using proper PPE.

What is a 'live working permit'?

• AA driving license
• BFormal authorization to work on energized electrical equipment under strict procedures✓
• CAny work authorization
• DNot necessary

Answer: A live working permit formally authorizes and documents work on live electrical parts, requiring competent personnel, additional controls, and strict procedures to minimize shock risk.