Your Fuse Box or more modern Consumer Unit is the origin of all the electrical circuits within your home. Usually this would be located next to or near to your Electricity meter and the incoming supply cable. Sometimes this may be outside in a meter box with the Consumer Unit or Fuse Box located indoors on the other side of the wall. They can also be referred to as a Distribution Board, although this would typically be the name for a larger unit used in a Commercial or Industrial setting.
A modern Consumer Unit Old style Fuse Box
The purpose of your Fuse Box or Consumer Unit is to divide the electrics into circuits of appropriate size cable, with a protective device to prevent the cable from overloading and causing a fire. These devices will usually be a re-wireable fuse wire (BS3036) or cartridge fuse in an old fuse box, or an MCB (BS60898) which stands for miniature circuit breaker. An MCB is much more effective than a fuse or fuse wire at disconnecting a circuit and much more robust should a high fault current occur. This is one of many characteristics that make a modern Consumer Unit highly recommended over the older style Fuse Box.
Typical fuse or MCB ratings would be 5 or 6 Amp for lighting and 16, 20, 30 or 32 Amp for socket outlet circuits. Other larger circuits such as an electric shower or cooker may use a 40, 45 or 50 Amp circuits. Generally the largest fuse or MCB rating in a home would be a 60 or 63 Amp, which would be for a very large cooker, shower or electric boiler/ heater. You may also find a circuit feeding a secondary Fuse Box or Consumer, known as a Sub-main supply, using one of these larger protective devices.
The Main Switch.
The first functional part of both a Fuse Box and Consumer Unit is the main switch. This is used to cut the power to every circuit fed from the Box or Unit, this may be all of the power in your house , or just circuits within a certain area such as a garage or out building. Clear labelling is very important so its clear exactly what you are switching off should you need to turn off the power. If you experiance a fault or serious problem with your electrics it may be necessary to keep this main switch off until a qualified Electrician can make things safe and restore power.
Other parts of a Consumer Unit
Another key component of a Consumer Unit is an RCD, or Residual Current Device. This would only be found in a Consumer Unit, an RCD will not fit into a Fuse Box. An RCD is a safety device which will hugely improve safety standards for your Electrical system. You can find out more about an RCD and why it is recommended to have one installed here- RCD Protection
Benefits of a new Consumer unit
Whilst older fuses still protect from electrical over current and fires, modern trip switches (MCB’s) found within new Consumer units will complete this task much more effectively and cut off the electrical supply much quicker. Modern consumer units are also far more convenient in that all circuits are protected by trip switches rather than wired fuses. This means that in the event that a fuse/switch goes or trips then it’s a simple matter of just resetting the switch rather than hunting for the appropriate fuse wire and tools.