CITB Specialists Specialist Trade Hazards 2 — Questions and Answers
Question 1: A gas engineer smells gas on arriving at a job. What is the first action?
- Do not operate any switches — ventilate the area and call the National Gas Emergency line (0800 111 999) (Correct answer)
- Test the gas detector and identify the leak source before ventilating
- Turn off the gas meter and begin work immediately
- Light a match to locate the source of the gas smell
Correct answer: Do not operate any switches — ventilate the area and call the National Gas Emergency line (0800 111 999)
On smelling gas, no electrical switches should be operated as a spark could ignite the gas. The area must be ventilated immediately by opening doors and windows, then the National Gas Emergency Service called on 0800 111 999.
Question 2: What is the main hazard of using an oxy-acetylene torch in a confined or poorly ventilated space?
- Oxygen depletion and build-up of toxic combustion products leading to asphyxiation and fire risk (Correct answer)
- Excessive noise from the torch
- UV radiation causing sunburn
- High temperature causing heat exhaustion only
Correct answer: Oxygen depletion and build-up of toxic combustion products leading to asphyxiation and fire risk
Oxy-acetylene equipment consumes oxygen and produces carbon monoxide and other combustion products. In confined or poorly ventilated spaces, this can cause oxygen depletion and toxic gas accumulation leading to asphyxiation and explosion risk.
Question 3: A specialist electrical contractor is working on a live panel. What regulation governs this work?
- Electricity at Work Regulations 1989 — live working is only permitted when dead working is not reasonably practicable (Correct answer)
- Any registered electrician may work on live panels at any time
- Live working is prohibited in all circumstances
- Only the site manager can authorise live working
Correct answer: Electricity at Work Regulations 1989 — live working is only permitted when dead working is not reasonably practicable
The Electricity at Work Regulations 1989 require that electrical systems be made dead before work begins unless it is not reasonably practicable to do so. Live working requires formal risk assessment, appropriate PPE, and trained personnel.
Question 4: What hazard is associated with polyvinyl chloride (PVC) pipe when it is cut or welded?
- Release of toxic chlorine-containing fumes requiring local exhaust ventilation (Correct answer)
- Risk of explosion during cutting
- Spontaneous combustion when heated
- Carcinogenic dust requiring FFP3 respirator
Correct answer: Release of toxic chlorine-containing fumes requiring local exhaust ventilation
Cutting, welding, or heating PVC releases hydrogen chloride and other toxic fumes. Local exhaust ventilation and appropriate respiratory protection are required when working with PVC in enclosed areas.
Question 5: What is the greatest risk when a plumber uses a blowtorch in a wall cavity?
- Setting fire to hidden timber or insulation causing a concealed fire (Correct answer)
- Melting plastic pipes in the cavity
- Disturbing asbestos in the cavity walls
- Damaging electrical cables by heat
Correct answer: Setting fire to hidden timber or insulation causing a concealed fire
Blowtorch flames in wall cavities can ignite hidden timber studwork, insulation, or other combustibles, creating concealed fires that spread unseen before being detected. Fire watch procedures and fire-resistant materials should be used.
Question 6: When must a specialist contractor check for asbestos before starting work?
- Before any work that may disturb building materials in structures built before 2000 (Correct answer)
- Only when working on buildings built before 1970
- Only when specifically instructed by the client
- Only plumbers and electricians are affected — other trades are exempt
Correct answer: Before any work that may disturb building materials in structures built before 2000
Any work that may disturb building materials in structures built before 2000 requires checking the asbestos register or carrying out a survey. Asbestos was used in many building products and disturbing it without precautions is extremely dangerous.
CITB Specialists Specialist Trade Hazards 2
A gas engineer smells gas on arriving at a job.
What is the first action?