Customer Distribution Board Checker

Fuse Board Checklist

We have put together a simple 4 stage process for checking the type of fuse board that you have and its suitability for accepting any changes to your installation. Or if you need to update it.

Stage 1 of 4  – Does your Consumer Unit have Miniature Circuit Breakers MCBs)?

These will be found behind the cover on your consumer unit and will look like switches similar to those below. Consumer Units are also known as Fuse Boards or Fuse Boxes.

Picture of a new distribution board

  • If YES, then go to stage 2
  • If NO, then you have an older Consumer Unit and this will need to be changed before any new additions to the installation can be carried out. For safety reasons consumer units of this age should be replaced to meet current wiring regulations.

(Please note that consumer unit layouts and colours vary by manufacturer)

Stage 2 of 4 – Does your Consumer Unit have space for an additional MCB?

This is known as a spare way and will likely be covered by a blanking plate.

The Consumer Unit in the picture above has three spare ways to the left of the image, but these could be in any position on the board and in any number.

  • If YES then go to stage 3. 
  • If NO then you would have difficulty getting new circuits installed i.e. garage supply.

Stage 3 of 4 – Is there at least one Residual Current Device (RCD) fitted in your consumer unit?

This device, an example of which is shown below, looks similar to an MCB but will have a test button as well.

Technically under the 17th Edition 2008 Electrical Regulations there should be two RCD’s as in the first picture..

  • If YES then go to stage 4.
  • If NOthen you should consider having the Distribution board changed.

    Because at a minimum all outdoor equipment should be protected by an RCD.

Close up on an RCD

Stage 4 of 4 – Is your Consumer Unit made by one of the following manufacturers?

  • If so, then it is likely you will be able to have an RCD installed into the existing distribution board.

Various Electrical Company Logo's

This is the end of the Fuse Board Checklist. You should have been able to identify whether your fuse board / consumer unit is suitable to easily accept an modifications to the installation.

Additional information


Miniature Circuit Breakers come in a variety of shapes and sizes, and are manufactured by different companies. The thing that they have in common, and the way that you can tell you have MCBs fitted to your fuse board, is that they have switches on the front – as illustrated in the image below.

Miniature circuit breakers (MCBs) are fitted in newer consumer units in place of fuses. They have the advantage that they can be manually reset without having to replace wire as in the case of the traditional fuse. The MCBs have either a button or lever that can be flicked to reset it.


A residual-current device (RCD), is an electrical wiring device that disconnects a circuit whenever it detects that the electric current is not correctly balanced. Such an imbalance is sometimes caused by current leakage through the body of a person who is grounded and accidentally touching the energized part of the circuit. A lethal shock can result from these conditions. RCD’s are designed to disconnect quickly enough to mitigate the harm caused by such shocks although they are not intended to provide protection against overload conditions.

RCD’s typically look similar to MCBs but have a test button facility as well.