Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, concerning a new fused spur installed in a domestic property and RCD protection requirements, is answered by SELECT:
Answer: BS 7671:2008 requires 30mA RCD protection for socket outlets generally, for supplies likely to supply equipment for use outdoors, and as a means of additional protection where cables are installed buried in walls less than 50mm from the surface in domestic type properties.
In addition, supplies to circuits in locations containing a bath or shower require this, and it may also be required for fault protection reasons if earth fault loop impedance values for installed circuits are not satisfactory.
In this instance, you are carrying out an alteration to an existing circuit and the requirements of BS 7671:2008 apply only to the cabling you are installing - you mention that you intend to install the cable on the surface of the wall in mini-trunking, so it appears that you do not have a requirement to install an RCD, provided that the existing circuit you intend to connect to satisfies requirements for fault protection in Chapter 41.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link:
www.voltimum.co.uk/consult.php?universe=consult.index.questions