Do socket-outlets added to an existing installation in domestic premises have to be RCD-protected?

Where socket-outlets are added to an existing circuit that is not already RCD-protected, either the circuit will need to have RCD protection added, or the new socket-outlets must incorporate RCD protection (except for a socket-outlet designated for a particular item of equipment, such as a freezer).

When an electrical appliance such as a boiler or electric towel rail is to be installed in a bathroom where there is no supplementary bonding, and the consumer unit has rewireable fuses and no RCD protection, how can the installer comply with the 17th Edition?

If an existing circuit of a location containing a bath or shower is extended, at least the extended part of the existing circuit must be provided with RCD protection. Supplementary bonding in a bathroom or shower room must be provided unless all the requirements in the 17th Edition for the omission of supplementary bonding are met.

A socket-outlet is to be added to an existing circuit. The work is not being carried out in a special location and the existing circuit has no RCD protection. The new socket-outlet is to be flush mounted 150 mm horizontally from an existing socket-outlet, and connected with wiring concealed in the wall. What is reasonably expected for the installer to do to comply with the 17th Edition?

A socket-outlet that is added to an existing circuit will need to have RCD protection (except for a socket-outlet designated for a particular item of equipment, such as a freezer).
In addition, if the wiring that is used to extend the existing circuit is concealed in the wall, then at least the extended part of the existing circuit will need to be suitably protected (by RCD or other means).

A switched, fused 13 A connection unit is to be added to an existing circuit. The work is not being carried out in a special location and the existing circuit has no RCD protection. The incoming services are bonded and the new switched fused connection unit is to be flush mounted 150 mm horizontally from an existing socket, and connected with wiring concealed in the wall. What is the reasonably expected for the installer to do to comply with the 17th Edition?

The connection unit does not require additional protection by RCD, though at least the extended part of the existing circuit will need to be suitably protected (by RCD or other means).

During the transition period (up to I July 2008), an electrical contractor may continue to design electrical installations to the 16th Edition. If a client refuses to accept supplementary bonding in a bathroom on the grounds that it is unsightly, can the contractor provide RCD protection to all the circuits serving the bathroom as an alternative, given what the 17th Edition will require? The contractor wishes to install the rest of the installation to the 16th Edition – that is, without RCD protection on other lighting circuits etc.

During the transition period, the installation work should comply with the requirements of either the 16th or 17th Edition, but not a selective mixture of both. However, from 1 July 2008, all new designs must comply with the 17th Edition.

With the increased requirement for circuits in domestic premises to be RCD-protected, it may be necessary for the smoke detector to be connected to an RCD-protected circuit, which may not be acceptable to the client. How could this issue be addressed without surface wiring?

When changing a consumer unit, do I need to provide RCDs for all circuits required by the 17th Edition to have additional protection, such as socket-outlets, bathroom circuits and cable concealed in walls and partitions?

Yes. There should be more than one RCD, and the circuits should be divided between them in order to minimize the consequences of tripping.

If an existing socket-outlet not having additional protection by RCD needs to be replaced, does such additional protection need to be provided for the replacement socket?

No. Such work would not be classified as an alteration or addition.

I need to replace a length of damaged cable in a circuit that is not RCD-protected. The 17th Edition would require a new circuit following the same route to have additional protection by means of an RCD. Do I have to provide such protection for the repaired circuit?

No. Such repair work would not be classified as an alteration or addition.

If I replace an existing electric shower, do I now have to provide RCD protection for it?

No, unless RCD protection is required by the manufacturer’s installation instructions, or a new circuit is required (to provide for increased load, for example).

When installing a non-electrical radiator in an existing bathroom, does the 17th Edition require it to be supplementary bonded?

Supplementary bonding would be required for any new extraneous-conductive-part installed in a bathroom or shower room unless all the other requirements of Regulation 701.415.2 have been met.

What needs to be done if the consumer unit of an installation protected by a voltage-operated earth-leakage circuit-breaker (VOELCB) is to be replaced?

Firstly, the electricity distributor should be asked whether an earthing facility for the installation can now be made available, which would avoid the need for a VOELCB or equivalent fault protection by RCD. If a new earthing facility cannot be made available, the VOELCB should be removed and appropriate RCD protection provided by the new consumer unit (as part of a modern TT system).