NEBOSH Fire Safety 1 — Questions and Answers
Question 1: What are the three elements required for fire to exist (fire triangle)?
- Fuel, oxygen, and ignition source (heat) (Correct answer)
- Fuel, water, and electricity
- Oxygen, nitrogen, and fuel
- Heat, smoke, and fuel
Correct answer: Fuel, oxygen, and ignition source (heat)
Fire requires three elements simultaneously: fuel (any combustible material), oxygen (typically from air — minimum ~16% concentration), and an ignition source (heat, spark, flame, friction, chemical reaction). Removing any one element extinguishes the fire or prevents ignition.
Question 2: What type of fire extinguisher is used for class B fires (flammable liquids)?
- Foam or CO₂ extinguisher (Correct answer)
- Water extinguisher
- Dry powder is first choice; water is acceptable for class B
- Class B fires require specialist military equipment
Correct answer: Foam or CO₂ extinguisher
Class B fires (flammable liquids: petrol, oils, solvents, paints) are extinguished by foam (which smothers and seals the surface) or CO₂ (which displaces oxygen). Water must never be used on flammable liquid fires as it spreads the burning liquid. Dry powder is also effective but leaves significant residue.
Question 3: What is a 'hot work' fire watch and what are the responsibilities?
- A designated person who monitors the area during and for 30–60 minutes after hot work to detect and extinguish any fires started by sparks or heat (Correct answer)
- A person who controls access to the hot work area
- A person who operates welding equipment
- A person who manages the permit to work paperwork
Correct answer: A designated person who monitors the area during and for 30–60 minutes after hot work to detect and extinguish any fires started by sparks or heat
The fire watch person remains at the work area throughout hot work and for a minimum of 30–60 minutes (or longer per fire safety standards) after work stops, monitoring for smouldering or delayed ignition. This is one of the critical controls on a hot work permit. Fires from hot work often start in hidden voids after work has finished.
Question 4: What is the recommended sequence of actions when discovering a fire?
- Alert (raise the alarm), Contain (close doors), Evacuate (leave and take others), Call emergency services (999/911/112), Attack only if safe and trained to do so (Correct answer)
- Attack the fire first with the nearest extinguisher
- Continue working and alert others on the way out
- Call emergency services first before raising the internal alarm
Correct answer: Alert (raise the alarm), Contain (close doors), Evacuate (leave and take others), Call emergency services (999/911/112), Attack only if safe and trained to do so
The fire action sequence: 1) Raise the alarm immediately (warn everyone), 2) Alert the fire service (call emergency number), 3) Evacuate all personnel using designated exits, 4) Only attempt to fight the fire if it is small, you are trained, you have the correct extinguisher, and an escape route is available. Life safety is always the priority.
Question 5: How does automatic sprinkler system work and what is its purpose?
- Heat-sensitive sprinkler heads activate individually when local temperature exceeds their rated threshold, discharging water to suppress the fire — not set off by smoke (Correct answer)
- All sprinkler heads activate simultaneously when one is triggered
- Sprinklers are activated by smoke detectors
- Sprinklers always cause more water damage than the fire would
Correct answer: Heat-sensitive sprinkler heads activate individually when local temperature exceeds their rated threshold, discharging water to suppress the fire — not set off by smoke
Sprinkler heads contain a heat-sensitive element (glass bulb or fusible link) that activates at a preset temperature (typically 57–68°C). Only heads in the fire area activate. Sprinklers suppress or extinguish over 99% of fires before fire service arrival, significantly reducing both fire and water damage compared to uncontrolled fire.
Question 6: What is the purpose of fire detection systems in buildings?
- To detect fire at the earliest possible stage, trigger alarms to alert occupants, and enable swift evacuation before conditions become untenable (Correct answer)
- To extinguish fires automatically
- To notify fire services but not occupants
- Detection systems are optional in Gulf commercial buildings
Correct answer: To detect fire at the earliest possible stage, trigger alarms to alert occupants, and enable swift evacuation before conditions become untenable
Early fire detection saves lives by maximizing evacuation time before fire gases and heat render escape routes untenable. Detection systems (smoke detectors, heat detectors, flame detectors, multi-sensor detectors) feed into a fire alarm panel that activates alarms, triggers suppression systems, and may directly alert the fire service.
NEBOSH Fire Safety 1
What are the three elements required for fire to exist (fire triangle)?