City & Guilds Electrical Installation (Level 3) Health, Safety and Environmental Practice in Building Services Engineering Syllabus

List, in correct order, the steps of the safe isolation procedure for a single circuit.

1) Identify the circuit/equipment; 2) Obtain permission to isolate; 3) Switch off and isolate; 4) Secure the isolation (lock off with a unique key/padlock); 5) Post warning notices; 6) Verify the approved voltage indicator on a known live source; 7) Test the circuit is dead; 8) Re-prove the voltage indicator on the known source.

Why must an approved voltage indicator be proved before AND after testing a circuit during safe isolation?

To confirm the test instrument was working correctly both before and after the dead test, proving that a 'dead' reading is genuine and not due to a faulty indicator. This is the 'prove–test–prove' sequence.

What equipment is used to lock off a circuit during safe isolation, and what principle governs the key?

A lock-off device/padlock fitted to the isolator, with the operative retaining the only (unique) key. This ensures the supply cannot be reinstated by anyone else while work is in progress.

Which standard/device type defines an 'approved voltage indicator' for proving dead, and what guidance note covers it?

A two-pole voltage indicator complying with GS38 (HSE Guidance Note GS38), which specifies safe test probes, fused leads and finger barriers. Non-contact testers and multimeters alone are not acceptable for proving dead.

State the hierarchy of control measures in correct order from most to least effective.

1) Elimination; 2) Substitution; 3) Engineering controls (isolation/guarding); 4) Administrative controls (procedures, training, signage); 5) Personal Protective Equipment (PPE). PPE is always the last resort.

Why is PPE considered the lowest/last level in the hierarchy of control?

Because it only protects the individual wearing it (not others), relies on correct use and fit, can fail or be removed, and does nothing to remove or reduce the hazard at source.

Give an example of 'elimination' versus 'substitution' as control measures on an electrical job.

Elimination: isolating and de-energising a circuit so there is no electrical hazard at all. Substitution: replacing a 230 V mains tool with a 110 V reduced-low-voltage tool, or a solvent with a less hazardous one.

What are the four main types of harm electricity can cause to the human body?

Electric shock, electrical burns, arcing/arc flash burns, and fire/explosion (and secondary injuries from falls caused by shock).

What is the conventional touch-voltage threshold above which AC is generally considered hazardous, and the standard UK mains voltage?

Voltages above approximately $50\,\text{V}$ AC are considered potentially hazardous (the conventional safe touch limit). Standard UK single-phase mains supply is nominally $230\,\text{V}$ AC.

Why is 110 V centre-tapped-to-earth (CTE) supply preferred for portable tools on construction sites?

With a centre-tapped earth, the maximum voltage to earth from either line is only $55\,\text{V}$ instead of 110 V, greatly reducing the severity of any electric shock.

State Ohm's Law and use it to explain why a lower body resistance increases shock danger.

$V = I \times R$, so current $I = \frac{V}{R}$. For a fixed voltage, lower body resistance (e.g. wet skin) produces a higher current through the body, increasing the danger of a fatal shock.

Approximately what level of AC current passing through the body is considered potentially lethal, and why?

Currents of around $50\,\text{mA}$ and above can cause ventricular fibrillation of the heart, which can be fatal. Even $30\,\text{mA}$ is the trip threshold for protective RCDs.

What residual current does a standard protective RCD trip at to protect against electric shock, and how fast?

A $30\,\text{mA}$ RCD provides additional protection against electric shock, disconnecting within around $40\,\text{ms}$ at a residual current of $150\,\text{mA}$ (and within 300 ms at 30 mA).

Which regulations govern the selection and use of access equipment and working at height in the UK?

The Work at Height Regulations 2005.

What is the hierarchy for managing work at height under the Work at Height Regulations 2005?

1) Avoid working at height where possible; 2) Prevent falls using a safe place of work or collective protection (guard rails, scaffold); 3) Mitigate the distance/consequences of a fall (nets, airbags, harnesses).

What is the correct angle ratio for positioning a leaning ladder safely?

The 1 in 4 rule (75 degrees): for every 4 units of vertical height, the base is set 1 unit out from the wall. This gives an angle of approximately $75^{\circ}$.

What checks should be made before using a stepladder or leaning ladder?

Inspect for damage (cracked/bent stiles, missing/worn feet, damaged rungs), ensure it is the right type and length, place on firm level ground, and confirm it is for short-duration light work only.

What is a mobile elevating work platform (MEWP) and what training certification is commonly required?

A MEWP (e.g. scissor lift or cherry picker/boom) provides a guarded working platform at height. Operators commonly require IPAF (International Powered Access Federation) certification.

Which regulations control exposure to hazardous substances, and what does the acronym stand for?

The Control of Substances Hazardous to Health Regulations 2002 — COSHH.

What document provides hazard and handling information for a chemical product under COSHH?

The Safety Data Sheet (SDS), supplied by the manufacturer/supplier, detailing hazards, exposure limits, first aid, storage and required PPE.

Give three examples of hazardous substances an electrician might encounter on site that fall under COSHH.

Asbestos (in older buildings), solvents/cleaners, silica dust from drilling/chasing masonry, lead, adhesives and resins, and fumes from soldering.

What does PPE stand for, and which regulations govern its provision?

Personal Protective Equipment. Provision is governed by the Personal Protective Equipment at Work Regulations 1992 (as amended 2022), which require suitable PPE to be provided free of charge by the employer.

List five common items of PPE used in electrical installation work and the body part each protects.

Safety helmet (head), safety goggles/glasses (eyes), ear defenders (hearing), dust mask/RPE (lungs), and safety boots with toe caps (feet); plus insulating gloves (hands) for electrical work.

Which UK regulations and main British Standard cover fire safety in non-domestic premises?

The Regulatory Reform (Fire Safety) Order 2005 (RRFSO), which requires a 'responsible person' to carry out a fire risk assessment.

State the fire triangle: the three elements needed for a fire to start.

Heat (ignition source), Fuel (combustible material) and Oxygen. Removing any one of these three extinguishes or prevents the fire.

What are the UK fire classes (A to F) and the type of fuel each represents?

Class A: solids (wood, paper); Class B: flammable liquids; Class C: gases; Class D: metals; Class F: cooking oils/fats. Electrical fires are not a class but are shown by an electrical symbol.

Which fire extinguisher type and colour code should be used on a live electrical fire, and which must NOT be used?

Use a CO2 extinguisher (black band) or a dry powder extinguisher (blue band), as they are non-conductive. Never use a water extinguisher (red) or foam on live electrical equipment due to electrocution risk.

What is the recommended action sequence on discovering a fire in the workplace?

Raise the alarm, call the fire brigade (999), evacuate via the nearest safe exit to the assembly point, do not use lifts, and only attempt to fight the fire if trained, safe to do so, and it is small.

Which regulations govern manual handling, and what is the first principle they require?

The Manual Handling Operations Regulations 1992 (MHOR). The first principle is to avoid hazardous manual handling so far as is reasonably practicable; if it cannot be avoided, assess and reduce the risk.

What does the acronym 'TILE' (or 'LITE') stand for when assessing a manual handling task?

Task, Individual, Load, Environment — the four factors to consider when assessing the risks of a manual handling operation.

Describe the correct kinetic lifting technique for picking up a load from the floor.

Plan the lift, keep feet apart for a stable base, bend the knees (not the back) keeping the back straight, get a secure grip, keep the load close to the body, lift smoothly using the leg muscles, and avoid twisting.