Smoke in the Basement Electrical Room
You are the security supervisor on duty at a five-storey office building with about 180 staff. At 14:10 the fire alarm sounds on zone 3, and the panel shows 'basement electrical room'. On investigation, you see light smoke from the basement stair door and smell burning insulation. The basement contains the main electrical panels and a UPS room. One of the two escape staircases has smoke on the ground floor; the other is clear. Several fire doors on floors 2–4 are wedged open with wooden blocks. The assembly point is across the road, and the fire brigade is 6–8 minutes away. You have two guards, four CO2 extinguishers, and water-hose reels. Staff are starting to come down the stairs, some carrying laptops and coffee.
1. What are your first actions, and do you attempt to fight the fire?
Read the worked answer
First: confirm the alarm, call 101/112 and state the address, basement electrical room, smoke, and number of floors; send a guard to meet the fire brigade; announce evacuation. Do not send staff into the basement. Fighting the fire is optional and only for a small, incipient fire with a clear exit, a CO2 extinguisher, and a second person as backup. Burning insulation in an electrical room can produce toxic smoke and hidden fire; the correct default is evacuate and isolate. If the basement door is hot, smoke is thick, or you cannot see the seat of the fire, close the door and leave. Do not use water on live electrical equipment. Ask the building electrician to isolate power only if it can be done safely. The priority is people, then containment by closing doors, then handover to the fire service.
2. How do you manage evacuation routes, the wedged fire doors, and a missing-person report?
Read the worked answer
Use the clear staircase as the primary route and physically close the smoke-affected stair door; put a guard at the ground-floor entrance to redirect people. Close every wedged fire door on floors 2–4-remove the blocks and shut the door; this is critical, because open doors turn a corridor into a chimney. Do not use lifts. At the assembly point, do a floor-wise roll call from visitor logs and department lists; report missing persons to the fire officer with name, floor, and last-seen location. Do not send guards back inside to search. If someone is trapped and the stair is smoke-free, the fire service does the rescue. Keep the entrance clear for the fire engine and record times. If smoke reaches both stairs, move people to a refuge area and seal the door.
3. Which extinguisher would you use, and what are the limits?
Read the worked answer
Use CO2 on the electrical fire: pull the pin, aim at the base of the flames, squeeze, sweep, and keep a safe distance; CO2 is clean and non-conductive. Do not use water or foam on live panels. A 4.5 kg CO2 extinguisher gives only about 10–15 seconds of discharge, so it is for a small fire, not a basement full of smoke. Limitations: it can displace oxygen in a confined space, the horn gets very cold, and it offers no cooling, so re-ignition is possible. Never enter a basement with only one exit or with thick smoke; back out if heat rises or the extinguisher empties. After any use, leave the area to the fire service, preserve the scene, and record the extinguisher ID and time used.