CITB Specialists Specialist Trade Hazards 1 — Questions and Answers
Question 1: An electrician discovers a damaged cable during first fix wiring. What is the correct action?
- Isolate and report immediately — do not attempt to use or work around the damaged cable (Correct answer)
- Continue working but make a note in the site diary
- Use insulating tape to repair the damage and continue
- Report it at the next weekly toolbox talk
Correct answer: Isolate and report immediately — do not attempt to use or work around the damaged cable
Any damaged electrical cable must be immediately isolated and reported to the site supervisor. Attempting to work around or patch a damaged cable risks electrocution, fire, and non-compliance with electrical safety regulations.
Question 2: What voltage range is used for temporary power supplies on most UK construction sites?
- 110V centre-tapped to earth (CTE) (Correct answer)
- 240V single phase
- 415V three phase
- 12V low voltage only
Correct answer: 110V centre-tapped to earth (CTE)
UK construction sites use 110V centre-tapped to earth (CTE) for portable tools and temporary lighting. This limits the maximum shock voltage to 55V earth to neutral, significantly reducing electrocution risk compared to 240V.
Question 3: A plumber is working with lead-based solder on an older property. What health hazard must be controlled?
- Lead fume inhalation — use local exhaust ventilation and respiratory protection (Correct answer)
- Lead dust on clothing — rinse clothing with cold water immediately
- Lead contamination of water — flush pipework for 30 seconds after soldering
- Lead burns — wear heat-resistant gloves only
Correct answer: Lead fume inhalation — use local exhaust ventilation and respiratory protection
Heating lead-based solder releases lead fumes which are toxic when inhaled. Local exhaust ventilation and appropriate respiratory protective equipment (RPE) are required to control lead fume exposure under COSHH regulations.
Question 4: What is the main hazard when a plumber works on a system containing pressurised hot water?
- Scalding from sudden release of steam and superheated water (Correct answer)
- Cold burns from refrigerant contact
- Chemical burns from water treatment additives
- Electrical shock from immersion heaters
Correct answer: Scalding from sudden release of steam and superheated water
Pressurised hot water systems can release superheated water and steam when opened, causing severe scalding injuries. Systems must be depressurised and allowed to cool before any work begins.
Question 5: Which specific hazard affects scaffolders working near overhead power lines?
- Electric arc flash from inadvertent contact with live conductors (Correct answer)
- Ultraviolet radiation from high voltage lines
- Magnetic field interference with tools
- Induced voltage causing radio interference
Correct answer: Electric arc flash from inadvertent contact with live conductors
Overhead power lines remain live unless the network operator confirms otherwise. Scaffolding tubes or equipment making contact with live overhead lines can cause fatal electric arc flash. Safe clearance distances must be maintained.
Question 6: What personal protective equipment is mandatory for a scaffolder when working at height?
- Hard hat, safety footwear, hi-vis vest, and a harness with lanyard when edge protection is not in place (Correct answer)
- Only a hard hat is legally required for scaffolders
- Hi-vis vest and gloves only
- No PPE is required on scaffolding with guard rails fitted
Correct answer: Hard hat, safety footwear, hi-vis vest, and a harness with lanyard when edge protection is not in place
Scaffolders must wear a hard hat, safety footwear (steel toe-capped), hi-vis vest, and use a harness with lanyard when edge protection cannot be provided. This protects against falling objects, falls, and improves visibility to site traffic.
CITB Specialists Specialist Trade Hazards 1
An electrician discovers a damaged cable during first fix wiring.
What is the correct action?