What should I do if my isolation switch catches fire?
Quick answer
If your isolation switch catches fire, do not touch it. Immediately call 999 and evacuate your home. If it is safe to do so without touching the burning switch, use your main consumer unit to cut all power — but only if accessible without passing through smoke or flames. Never use water on an electrical fire. Once the fire service has attended and confirmed the building is safe, do not restore power until a qualified electrician has inspected and replaced the damaged components. Isolation switch fires are most commonly caused by loose connections, overloading, or internal component failure.
🏠Homeowner view
An isolation switch catching fire is a serious electrical emergency — here is what you need to know and do.
Immediate steps to take:
Call 999 immediately — do not delay, even if the fire appears small
Evacuate everyone from the property without stopping to collect belongings
Do not touch the switch — it may be live and conducting heat or flame
Only cut power at the main consumer unit (fuse board) if it is safely accessible without entering a smoke-filled or flame-affected area
Never use water on an electrical fire — use a CO2 or dry powder extinguisher only if trained to do so and the fire is very small
What causes an isolation switch to catch fire?
Isolation switches (also called isolator switches or main switches) can catch fire for several reasons:
Loose terminal connections — the most common cause, creating resistance, heat, and eventual ignition
Overloading — drawing more current than the switch is rated for
Age and deterioration — older switches may have degraded insulation or contacts
Poor or DIY installation — incorrectly rated or poorly terminated equipment
Moisture ingress — particularly in outdoor or garage consumer units
After the fire service has attended:
Do not restore power under any circumstances until a qualified electrician has inspected the installation
Request an EICR (Electrical Installation Condition Report) to assess the wider installation
The affected switch, consumer unit, and associated wiring must be replaced before power is restored
Check your home insurance policy — fire damage caused by electrical faults is typically covered, and your insurer may require a professional report
When to call an electrician:
As soon as the fire service confirms it is safe to re-enter the building, contact a Part P registered electrician (NICEIC, NAPIT, or ELECSA registered) immediately. This is not a repair you can do yourself — it requires professional inspection, testing, and certification before the supply can safely be restored.
⚠️ Never restore power to a fire-damaged electrical installation yourself. This could cause a second fire or electrocution.