RCDs (residual-current device) is every electrician’s favourite subject in the designing of new electrical installations or additions to existing installations. As per the 17th Edition, socket outlets required the additional protection of a 30mA RCD on circuits 20 amps and under, this has now been changed, under the 18th Edition, to socket outlet circuits 32 amps and under (BS7671:2018 page 59 reg – 411.3.3).
Interestingly, “NOTE 3” suggests “luminaire track systems, etc.” is not regarded as a socket outlet.
Installation of Cables
Regulation 521.10.202 (page 138), covers the clipping of wiring systems with metallic clips, saddles, etc. We can only assume that this regulation has been highlighted by the tragedy of Grenfell and other such incidents as it is widely known that everything is acted upon on a reactive opposed to proactive basis.
This regulation did previously exist in the 17th Edition 3rd amendment as Regulation 521.11.201 notes 1 and 2 but only covered wiring systems over “escape routes,” this has now changed in the 18th Edition to ALL “wiring systems.”
NOTE 4 of Regulation 521.10.202 covers the types of fixing that would meet this requirement for supporting cables, listing supports previously mentioned and more.
Surge protection devices (SPDs)
This is an area that has drawn a lot of attention and the IET have obviously spent a lot of time on. This is also an area that is to be taken seriously as most businesses require large communications requirements for their day to day running and SPDs are great additional protection for such costly equipment.
Most MI’s (manufacturer’s instructions) give an average life expectancy of SPDs of 7 to 10 years, this, for the facility management companies reading, will generate a visual PPM and remedial works in the installation of SPDs or the replacing of “out of date” SPDs, whereas, for the estates teams reading this article they have the peace of mind that there is an additional item of protection that will safe guard the sensitive equipment they deem to be business critical. The selection of such equipment should be determined by Regulation 443.3 points “i – iv” page 101.
Types of SPDs to be used in different locations around the installation from the origin to the circuit containing sensitive equipment are descripted in Regulation 534.4.1 page 161.
Finally, a pointer for testers and testing, the insulation resistance testing of SPDs is covered by Regulation 643.3.2 page 232 paragraph 4 states “(SPDs)….such equipment shall be disconnected before carrying out the installation resistance test….”
To summarise, there have been numerous changes from 17th to 18th Edition, the selected few in this article are areas that may affect the day to day business in both installations and maintaining our current and future clients’ electrical installations.
Below is a list of accredited governing or informative bodies: