Updating a Consumer Unit

Upgrading an older consumer unit to one incorporating two residual current devices, RCDs is a task that many people will these days have to consider. The Seventeenth version of the cabling legislation demands most circuits in a family house to be safe by an RCD. It is typically a much better and less expensive option to upgrade the consumer unit rather than change the active set up in order to conform with the fresh rules.

A consumer unit utilizing rewireable BS 3036 fuse carriers was improved to a Seventeenth release split load board adding circuit 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 taken out

17th edition wiring legislation relating to consumer units

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

Replacing the consumer unit may also require some supplemental electrical work, to permit the unit installation to fulfill the requirements set by the new wiring legislation. This might include splitting circuits or running in new cable. An older residence might include all the lighting and electrical sockets delivered by just two circuits. It would be better practice to split these so that the lighting and sockets for each surface are on independent circuits with their own circuit breaker. Other problems that call for attention include assimilated neutrals. This is where a neutral return pathway was not available and a link to yet another circuit has been created. Repairing this fault would, in many cases, require a new cable to be set back to the consumer unit.

Old consumer unit taken out and taking away outdated cables

Reviewing earthing and bonding arrangements

Before the consumer unit is replaced, the electrical contractor will have looked at the distributor’s equipment at the source of the installation and the earthing and bonding arrangements. This is to ensure that they are safe and that they abide with the regulations. A lot of older homes do not have a dual pole isolation button amongst 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 commence. The provider may assist by putting in this main switch.

Nearly all home-based properties have the following arrangement at the origin: the service cable going into 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 primary 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 other services. These arrangements vary with larger or smaller sized installs; your electrician will guide you on what is expected.

Putting in wall support
Creating first connections to 17th edition RCD board

Installing the new consumer unit

The nature of this job, disconnecting the overload protection and joining the cable to a new means of basic and fault safety means that the electrical installer will have worked on all circuits. He will consequently have to carry out an electric experiment on all circuits to be sure that they are secure and will then have to issue an electrical installment certificate before the job is passed over. Any troubles identified on a circuit will have to be corrected before the circuit is energised.

Setting up circuit connections
New consumer unit in place available for labelling

Safe practices Note
Just 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 placed at the isolation place announcing that work is being carried out and that electrical power must not be returned to the circuit.

If you are not 100% sure that you know exactly what you are doing call in a competent electrician. Building rules are getting to be stricter, demanding 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 residence could be against the new rules and could invalidate your home insurance plan, if in question check first!