What does an RCD do

An RCD (Residual Current Device) is an electrical safety device that monitors the leakage to earth in an electrical circuit, it trips the supply when the leakage to earth goes above its set limit, (typically in a domestic situation this is 30ma (milli amps).

For new installations and rewires in domestic premises, all socket-outlets need to have additional protection by RCD, except perhaps for those intended to supply particular items of equipment such as freezers. Any socket-outlet not having RCD protection needs to be specifically labelled or otherwise suitably identified to indicate its intended use, such as ‘freezer only’. However, if the wiring to a dedicated socket-outlet is concealed in a wall or partition at a depth of less than 50 mm, or if the internal construction of the wall or partition includes metallic parts other than metallic fixings, the circuit will still need to be suitably protected (by RCD or other means)

The benefit of having an RCD in circuit is that should a person or livestock coming into contact with a live conductor for example by cutting the cable with a lawnmower the risk of a dangerous electric shock or burn becomes negligible.


There are 3 main types of RCD:

Fixed RCDs are installed in your consumer unit (or fuse board) and this provides the best protection as it covers all sockets and appliances on the circuit connected through it.This is the case with all new board installed in line with the 17th edition of the wiring regulation. We at PES are happy to give you a price to upgrade your distribution board

Socket-outlet RCDs this is a socket with an RCD fitted to the front of the socket with a test and reset button.

Plug in RCDs this type are like an adaptor and can be plugged into any socket and like the socket outlet have a test and reset button. If you have no RCD protection in your house we strongly recommend you buy one of these if you are using electrical equipment outside.

If you live in a new house wired to the 17th edition of the wiring regulations then you should have a distribution board fitted with RCD’s. Also if you have had some Part P work carried out your electrician may have upgraded your distribution board. If you have an older installation and have no RCD protection then it may be wise to consider have an electrical condition report carried out and have a qualified electrician give you some advise as what is needed to upgrade. Remember it is not the law to upgrade your distribution board but it may save your life if you do.

If you do need a reliable electrician please call PES Electrical Installations on 01953 711076 or contact