Safety and emergencies

Treat it as an emergency if there is smoke, flames, a burning smell, scorch marks, melting plastic, sparking, an electric shock from a fixed fitting, or water reaching wiring or a consumer unit. In those cases isolate the circuit if it is safe and call 999 where there is fire or injury.

A total loss of power, a breaker that will not stay on, or a circuit you have had to switch off is urgent but not usually a 999 matter — it needs investigating before the circuit is used again.

The main switch is inside the consumer unit (fuse box), usually the largest switch, often marked Main Switch or 100A. Pushing it down or to OFF isolates the whole installation. Individual circuits can be switched off one at a time using the smaller breakers.

Only do this if you can reach the board from a dry position with dry hands and there is no smoke or heat coming from it. Never remove the sealed supplier cut-out fuse or open the meter — that equipment belongs to the network operator.

Unplug whatever is connected to it if the plug is cool enough to grip, switch that circuit off at the consumer unit and stop using the socket. Heat and discolouration normally mean a loose connection or an overloaded accessory, both of which are recognised fire risks.

Do not simply replace the faceplate — the connection behind it and the circuit feeding it should be checked.

A faint hum from a device under load can be normal, but a loud buzz, a crackle, a rattling breaker or any warmth or smell from the board is not. Loose terminations and failing protective devices both produce noise before they fail properly.

Stop using heavy loads, keep the cupboard clear and have it inspected. If there is any smell of burning or heat on the enclosure, switch off the main switch.

Check whether neighbours have power and whether your main switch and breakers are still on. If the street is out, call 105 free from any phone — it connects you to your local network operator, and power cuts are their responsibility, not an electrician's.

If your neighbours have power and your main switch is on but nothing works, the fault is inside the property or at the supply cut-out, and it needs investigating.

The service cable, the sealed cut-out fuse and the earthing arrangement belong to the distribution network operator (call 105). The meter belongs to your energy supplier. Everything from the consumer unit onwards — the tails, the board, the circuits, the accessories — is the property owner's and is an electrician's work.

Electricians cannot break the supplier's seals or replace a cut-out fuse; that has to be arranged with the network operator or supplier.