Consumer units
Consumer unit (fuse board) basics
Your consumer unit — most people still call it "the fuse board" even though modern ones don't use fuses — is the single point every circuit in your home runs through. Understanding roughly what's in it makes the difference between a five-minute reset and an unnecessary emergency call-out.
What's inside
A main switch that cuts power to the whole property. A row of circuit breakers (MCBs), each protecting one circuit — lighting, sockets in a particular area, the cooker, and so on — that trip if that circuit draws too much current. And one or more RCDs (residual current devices), which trip much faster than a breaker if they detect current leaking somewhere it shouldn't, such as through a person — they're the main protection against electric shock.
When a trip is normal
A single breaker tripping right when you plugged something in — a faulty appliance, an overloaded extension lead, a hairdryer with a worn cable — is usually the appliance's fault, not the wiring's. Unplug whatever you were using, reset the breaker once, and if it holds, the appliance is the culprit.
When it isn't
If the main RCD trips with nothing unusual plugged in, if a breaker won't stay reset at all, or if it happens repeatedly across different appliances, that points to a fault in the fixed wiring or the consumer unit itself — not something to keep resetting. That's when it's worth booking an electrician rather than living with an intermittent trip.
Still not sure, or it’s happening right now?
In immediate danger, call 999 first. Otherwise, get matched with an electrician now →