Changes to the Regulations 2008
You may like to have a look at this guide to the new Consumer unit regulations
Consumer unit guide (pdf)
A significant change is the introduction of Regulations requiring
additional protection by RCDs.
There are 3 points of consideration,
The definitions for persons are important to consider when we look at the requirements for protection of circuits supplying socket outlets. Regulation 411.3.3 requires that an RCD of not exceeding 30mA be provided for: i. Socket outlets up to 20A that for general use by "ordinary persons". ii. Mobile equipment up to 32A that is for use outdoors. Exceptions to 411.3.3 are permitted where: iii. Use of socket outlets is under the supervision of someone "skilled" or "instructed". iv. Specifically labelled or otherwise suitably identified socket outlets provided for a particular item of equipment. This is a change from the 16th Edition that required only socket outlets 'reasonably expected' to supply equipment used outside the equipotential zone to have RCD protection e.g. used for an Electric lawn mower. Now under the requirements of the 17th edition it is likely that every socket outlet in a domestic installation will require RCD protection not exceeding 30mA.
Cables buried in the wall Here we need to consider Section 522, Selection and erection of wiring systems in relation to external influences. The particular requirements of this section apply to cables which are concealed in a wall or partition at a depth of less than 50mm, or where metal partitions are used. The definitions for persons are once again important for this section. There are 5 options of installing cables in walls. The cables shall: i. incorporate an earthed metal covering which is suitable as a protective conductor. Eg SWA cable. ii. Be enclosed in earthed metal conduit, such that is suitable as a protective conductor. iii. Be enclosed in earthed metal trunking, such that is suitable as a protective conductor. iv. Be protected against damage from penetration by nails or screws. v. Be installed in a safe zone. This is much the same as the 16th Edition requirements and the usual option is to install cables in a dedicated safe zone. However, where an installation is not under the supervision of someone skilled or instructed, regulation 522.6.7 applies. In this regulation where (v) only from above is used then the cable must have additional protection by the use of a RCD not exceeding 30mA. This would apply where thermoplastic (PVC) wiring systems are used, this is typical in most domestic installations and some commercial installations.
Section 701, Locations containing a bath or shower Regulation 701.411.3.3 requires that all circuits within this location shall be additionally protected by an RCD not exceeding 30mA. This would mean 230V lighting, the 230V supply to the source for SELV, a shower circuit and bathroom heater for example will all need RCD protection. A standard 13A socket outlet is now permitted in this location provided however the socket outlet is more than 3m from the boundary of zone 1. The 16th Edition required local supplementary bonding be provided connecting together all exposed and extraneous conductive parts in the zones. This is no longer required in this location provided the following conditions are met: • All final circuits of the location comply with the automatic disconnection requirements according to regulation 411.3.2. • All circuits are RCD protected in accordance with 701.411.3.3. • All extraneous-conductive parts of the location are effectively connected to the protective equipotential bonding according to regulation 422.214.171.124 (Previously termed main equipotential bonding). All circuits in locations containing a bath or shower shall be protected by an RCD not exceeding 30mA.