Responding to an Electrical Fire

An electrical fire is any fire where the source or a significant component involves live electrical equipment — burning wiring, sparking switchgear, a burning appliance still connected to power. The presence of electricity in the fire fundamentally changes the response, because using water on a live electrical fire can cause electrocution of the person attempting to fight it.

Electrical fires require specific suppression agents, and the decision about whether to fight or evacuate depends on factors beyond just the fire's size.

Why Water Must Never Be Used on a Live Electrical Fire

Water conducts electricity. When water contacts a live electrical circuit, current can flow through the water stream back to the person holding the hose. This can cause:

• Electrocution of the person using the water
• Spreading of the fault to adjacent systems
• Flash arcing in switchgear (breaker panels, distribution boards)

This applies to:

• Direct water from a tap or bucket
• Standard water fire extinguishers (red label, UK)
• Any water-based solution including wet cloths applied to live equipment

A wet cloth can be used on a non-live electrical fire — once you have confirmed the equipment is disconnected from power. But until you have confirmed isolation, treat the fire as live.

The First Step — Isolate the Power

Before any suppression attempt:

1. Identify the circuit or appliance involved.
2. Turn off at the appliance — switch off at the socket and at the appliance if accessible without going near the fire.
3. If the fire is in the wall or in wiring — turn off at the consumer unit (fuse box / circuit breaker panel). Turn off the relevant circuit breaker if identifiable; turn off the main switch if not.
4. If you cannot safely isolate, treat the fire as live throughout your response.

Once power is isolated, the fire behaves as a standard Class A (solid materials) fire and can be treated accordingly. However, components may remain energised from capacitors or battery backup — exercise caution.

Correct Extinguishers for Electrical Fires

Extinguisher Type	Safe on Electrical Fire?	Notes
CO2 (black label, UK)	Yes — primary choice	Leaves no residue; safe up to 1,000V at 1 metre; preferred for switchgear and electronics
Dry powder ABC (blue label)	Yes (with precautions)	Effective but leaves a damaging powder residue; safe up to 1,000V at 1 metre; avoid on sensitive electronics
Water mist (white label, some types)	Check rating — demineralised water mist only	Some water mist extinguishers are rated for electrical fires; standard water mist is not
Water (red label)	Never on live equipment	Electrocution risk
Foam (cream label)	Never on live equipment	Foam is conductive
Wet chemical (yellow label)	Never on live equipment	Designed for cooking oil only

CO2 extinguisher for the home: If you have any electrical appliances in your home (you do), a CO2 extinguisher is the correct supplementary fire extinguisher to have. It is also safe on paper and fabric fires. Typical home size is 2kg.

Important limitation: CO2 extinguishers discharge quickly (approximately 8–10 seconds for a 2kg unit). They are effective for small electrical fires in appliances and switchgear, not for a large structure fire involving electrical components.

Specific Electrical Fire Scenarios

Burning Appliance (Toaster, Washing Machine, TV, etc.)

1. Turn off at the socket — do not touch the appliance.
2. Pull the plug from the socket if you can reach it safely — this fully isolates the appliance.
3. If the fire is small and confined to the appliance: CO2 or dry powder extinguisher using PASS technique (Pull pin, Aim at base, Squeeze, Sweep).
4. If the fire has spread beyond the appliance to adjacent surfaces: evacuate and call 999.

Burning Socket, Switch, or Extension Lead

1. Turn off at the consumer unit for the affected circuit — do not touch the socket.
2. Do not use water — even after isolation, residual charge or unknown live adjacent circuits are possible.
3. CO2 extinguisher if fire is contained to the socket area.
4. Isolate the entire building main if the circuit cannot be individually identified.

Consumer Unit (Fuse Box) Fire

1. Do not open the consumer unit door — arcing inside is contained; opening exposes you.
2. Turn off the main incoming switch if accessible outside the unit.
3. Call 999 — a consumer unit fire is a major electrical emergency.
4. Evacuate — consumer unit fires can spread rapidly through wiring throughout the building.

Burning Cable in Wall (Smell, Heat Without Visible Flame)

This is a serious and particularly dangerous scenario:

1. Isolate at the consumer unit — all circuits if you cannot identify the specific one.
2. Do not use a drill or saw on the wall to access the cable — this risks electrocution and can introduce oxygen to a smouldering fire.
3. Call 999 — hidden cable fires require professional investigation; the fire brigade can use thermal cameras.
4. Evacuate if the smell intensifies or if visible smoke appears.

⚠️ A burning smell from inside a wall — without visible flame — is a serious warning sign that should not be investigated by removing wall materials yourself. Electrical fires inside wall cavities can smoulder for hours before emerging. Turn off electrical supply to that area and call the fire brigade for a precautionary inspection.

When to Evacuate Rather Than Fight

The standard rule: fight only if:

• The fire is smaller than a waste bin
• The power is isolated
• You have the correct extinguisher
• The exit is behind you

Evacuate immediately if:

• The power cannot be confirmed isolated
• Smoke is filling the room
• The fire involves the consumer unit or building wiring
• The fire is inside a wall
• There is any arcing, sparking, or crackling from the fire source

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Quick Reference

Scenario	Action
Electrical fire — first step	Isolate power at socket and consumer unit
Fire on live equipment	CO2 extinguisher; never water
Fire on isolated equipment	CO2 or dry powder
Burning consumer unit	Evacuate; call 999; do not open the unit
Burning wall cable smell	Isolate all circuits; evacuate; call 999
Water on electrical fire	Never — electrocution risk
Fire larger than waste bin	Evacuate; call 999