• What's a 'Consumer Unit'?

Consumer unit or Fusebox

The fusebox also known as consumer unit should be easy to find. You should make sure you know where it is in case you ever need to turn the electricity off in an emergency. It usually contains three things, and they are used to control and distribute electricity around your home. They are: The main switch; Fuses and/or circuit breakers; and Residual Current Devices.

Modern consumer unit
Modern Consumer Unit with main switch (A), circuit breakers (B) and RCDs (C)

A) Main switch

B) Fuses or Circuit Breakers

C) Residual Current Device

Old Fusebox
Old style Fusebox with main switch (A), re-wireable fuses (B) and no RCD

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Main Switch

this allows you to turn off the electricity supply to your home. You might have more than one mains switch, for example if your home has electric storage heaters. In this case you may have a separate fusebox.

Main Switch

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Residual Current Devices (RCD)

These are switches that trip a circuit under dangerous conditions, and instantly disconnect the electricity. If your home has one or more RCD, test them regularly. Just follow the instruction label, which you should find near to the RCD. It should read as follows: “This installation, or part of it, is protected by a device which automatically switches off the supply if an earth fault develops. Test every three months by pressing the button marked ‘T’ or ‘Test’.” Testing the button every three months is important. The device should switch off the electricity. You should then switch it back on to restore the electricity. Do not hold the test button for a long period if the RCD does not trip. If it doesn’t switch off the electricity when you press the button, contact a registered electrician.

Residual Current Device (RCD)
RCD

Residual Current Device (RCD)
RCBO

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Circuit Breakers (MCB)

These are automatic protection devices in the fusebox that switch off a circuit if they detect a fault. They are similar in size to fuses, but give more precise protection. When they ‘trip’, you can simply reset the switch. But make sure you correct the fault first.

Circuit Breaker (MCB)

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Fuses

Rewirable fuses have a piece of special fuse wire running between two screws. When a fault or overload current flows through the fuse wire, it will become hot and melt. The melted fuse breaks the circuit, disconnecting the faulty circuit and keeping you safe.

Rewireable Fuse

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Old Fuseboxes

If your fusebox has a wooden back, cast iron switches, or a mixture of fuses it is likely that it dates back to before the 1960s and will need to be replaced.

old switchfuses

 
 

Information from The Electrical Safety Council, see www.esc.org.uk for further information and advice

 
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