Replacing a Consumer Unit

Upgrading an aged consumer unit to one integrating two residual current devices, RCDs is a activity that many people today will currently have to think about. The Seventeenth model of the cabling rules necessitates most circuits in a domestic house to be guarded by an RCD. It is normally a much better and less expensive alternative to enhance the consumer unit rather than alter the active set up in order to comply with the fresh rules.

A consumer unit using rewireable BS 3036 fuse carriers was improved to a Seventeenth release split load board adding signal breakers occasionally referred to as MCBs, miniture circuit breakers. The circuits on the new consumer units are protected by two residual current devices. Power and lighting circuits for the same floor are split between the RCDs on different sides of the board. This is so that in the event of a fault all the circuits on a particular floor are not cut-off from the supply.

Consumer unit to be improved with fuse carriers removed

17th edition cabling legislation related to consumer units

The new wiring regulations presented in 2008 request that all circuits are safeguarded by RCDs. Usually the simplest way to conform, particularly if the current fuse box is out dated, is to update.

Swapping the consumer unit may also entail some extra electrical work, to enable the unit installation to fulfill the criteria set by the new wiring legislation. This might include breaking circuits or running in new cable. An older house might include all the lighting and sockets provided by just two circuits. It would be better practice to split these so that the lighting and sockets for each floor are on different circuits with their own circuit breaker. Other issues that demand consideration include borrowed neutrals. This is where a neutral return path was not accessible and a link to yet another circuit has been created. Solving this fault would, in many cases, need a new cable to be placed back to the consumer unit.

Old consumer unit removed and doing away with outdated wires

Checking earthing and bonding arrangements

Just before the consumer unit is replaced, the electrician will have checked the distributor’s apparatus at the origin of the installation and the earthing and bonding arrangements. This is to be certain that they are safe and sound and that they comply with the rules. A large number of older properties do not have a dual pole isolation switch between the meter and the consumer unit which means that the electrical distributor will have to be called in before work on the consumer unit can start. The distributor may assist by putting in this main switch.

The majority home-based properties have the following arrangement at the origin: the service cable entering a sealed unit with a fused line (live) conductor with a 100amp main fuse or service cut-out, 25mm meter tails, a electronic or analogue meter, 25mm tails to consumer unit. It is here that the main switch would be placed. The ‘automatic disconnection of supply’ would be provided for by 16mm earthing conductor and 10mm main bonding conductors to gas, normal water and additional services. These arrangements vary with larger or smaller sized installs; your electrician will advise you on what is expected.

Fitting wall support
Producing first connections to 17th edition RCD board

Adding the new consumer unit

The nature of this work, disconnecting the overload safeguards and linking the wire to a new means of basic and fault protection suggests that the electrical installer will have worked on all circuits. This individual will for that reason have to carryout an electrical experiment on all circuits to make certain that they are secure and will then have to issue an electrical installment certificate before the work is handed over. Any errors found on a circuit will have to be remedied before the circuit is energised.

Arranging circuit connections
New consumer unit in location available for labelling

Basic safety Note
Before any work is carried out on an electrical circuit, the circuit must be separated and closed off or the fuse carrier taken out. A sign ought to be positioned at the isolation point saying that work is being carried out and that electrical power must not be returned to the circuit.

If you are not 100% certain that you understand precisely what you are carrying out call in a competent electrical contractor. Building policies are getting to be stricter, requiring that experienced individuals only carry out electrical work, with most works having to be notified to the local authority. Changing the electrical installation in your household could be against the new rules and could invalidate your home insurance coverage, if in doubt check first!