Mr. G Domestic Electrical

Probably one of the most critical parts of the home installation, the consumer unit (sometimes called fuse box) controls the distribution, switching and protection to the different circuits.

When the house was initially wired, the fuse box / consumer unit was selected to comply with regulations at the time. These regulations change, typically 3 times a decade - so, a 30 year old building that needs updating could have missed at least 9 editions and these changes usually require updated equipment. The regulations are not 'red tape', they are there primarily for the protection of life / property. A new regulation is usually created because something happened (a death or fire) that wasn't covered already.

The regulations are not retrospective, you don't need to change the consumer unit to comply with current regulations, so long as it complied with the regulations valid at the time of installation. However, new circuits, changes, modifications must comply with the latest regulations (and you should be given a certificate to confirm this). So, if you required a new circuit for a socket and the current regulations now require that a new socket be protected by an RCD (Residual Current Device), but you don't have one in your consumer unit, then the new circuit cannot be installed without updating the consumer unit (or adding an RCD to it).

If you are planning a new kitchen, bathroom, conservatory etc you need to check with your electrician beforehand that any new circuits and alterations will comply. In some cases, the 'electrics' are 'planned' to be added at the end as an after thought. This can create additional and avoidable expense. If the builder, plumber or kitchen fitter tells you that they will 'do' the electrics be wary, ask whether a certificate and notification will be provided and then confirm that they are registered here.

Some work is notifiable to Local Building Control under Part P of the Building Regulations:

• The installation of a new circuit
• The replacement of a consumer unit
• Any addition or alteration to an existing circuit in a special location (such as a bathroom)

Changing a consumer unit can be expensive, mainly down to the time taken to install it correctly.

• Circuits need to be tested prior to the change. This to confirm there isn't an existing fault and the wiring is safe to connect. You may have a fault that will be detected by the new protection device. Repairs might be needed before the new board is fitted
• The installation is powered off. The power needs to be disconnected at the cables coming into the board; this generally requires an isolator. If there is no isolator fitted, your electricity supplier may need to fit one
• Circuits are disconnected
• The consumer unit board is replaced
• Circuit protection devices added to the board
• Circuits reconnected
• Circuits dead tested - continuity and insulation testing
• Installation powered up
• Circuits live tested - Loop and RCD testing.
• Certification and notification

Generally, for a typical 3 bed home:

• Testing should be done the installation several days or a week prior to the board change to identify any issues or remedial work required. Time = allow a day.
• Carry out remedial work found during the testing, so the installation is in a good state and plan a day where there will be no power. Time = as required - depending on work needed.
• Replace the consumer unit, power off in the morning and work through disconnection, reconnection and testing. Time = allow a day - depending on the number of circuits.

If you have any questions about this please send me a message through the contact page.