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Circuit Breaker Won't Reset

A trip switch in your consumer unit will not stay in the on position no matter what you try.
Updated
How urgent
High risk
Who fixes it
An electrician

What's happening?

When a circuit breaker (MCB) or RCD will not reset at all (it springs back to the off position immediately or will not latch) it indicates either an active fault on the circuit that is still present, or the protective device itself has failed. This is more serious than a circuit that trips occasionally, because it means the fault is persistent.

What usually causes it?

  • Active short circuit on the circuit (live touching neutral or earth)
  • Severe earth fault with very low insulation resistance
  • Water ingress into wiring, sockets, or fittings on the circuit
  • Mechanically failed MCB or RCD that can no longer latch
  • Melted or damaged cable creating a permanent fault
  • Pest damage to cables (rodents chewing through insulation)

Is it dangerous?

A circuit breaker that will not reset is a high-priority issue. The device is telling you there is an active, serious fault. Do not attempt to force it into the on position or hold it in place. Do not bypass it or use any method to keep it switched on. The protection is preventing a fire or electric shock.

Can I fix it myself?

Switch off all MCBs protected by the device and try resetting it. If it resets with all MCBs off, turn them on one at a time to find the faulty circuit. On the faulty circuit, unplug everything and try again. If the MCB physically will not latch (the mechanism feels broken), the device itself has failed and needs replacing by an electrician. Never force a trip switch or wedge it in the on position.

When should you call an electrician?

Call an electrician immediately. A circuit breaker that will not reset means there is either an active serious fault or a failed protective device. Both scenarios require professional attention. If the affected circuit includes essential services like your fridge or heating, explain this when booking so the electrician can prioritise.

What will the electrician actually do?

  • Test the protective device to determine if it has mechanically failed
  • Disconnect the circuit and test for short circuits and earth faults
  • Carry out insulation resistance and continuity testing to find the fault location
  • Inspect the circuit for physical damage, water ingress, or pest damage
  • Replace the faulty MCB or RCD if the device itself has failed
  • Repair the circuit fault and verify the installation is safe before restoring power

Who fixes this

What it usually costs

Emergency Electrician Cost
£80–£100 / hour

Questions people ask

Why won't my trip switch go back up?

Either there is an active fault on the circuit that the device detects the moment it resets, or the trip switch mechanism itself has physically failed. Both need an electrician to diagnose and fix.

Can I hold the trip switch in the on position?

Absolutely not. Forcing a trip switch on defeats the safety protection and could result in a fire or electric shock. The device is tripping for a reason.

Is the trip switch broken or is it a wiring fault?

An electrician can determine this quickly. If the device resets with the circuit disconnected, the fault is in the wiring. If it will not latch even when disconnected, the device itself has failed.

What affects an MCB replacement?

The device type and rating, compatibility with the consumer unit, test results, and whether the circuit has an underlying fault determine the work required.

Could rodents have caused the problem?

Yes. Mice and rats chew through cable insulation in lofts, under floors, and in cavity walls. This creates short circuits and earth faults. If pest damage is found, all affected cables will need replacing and you should address the pest problem.

Sources & References

  1. BS 7671: IET Wiring Regulations (18th Edition)
  2. HSE: Electrical Safety at Work
  3. IET: BS 7671 Guidance Publications
  4. Electrical Safety First: Safety Guidance

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