522.6.203 RCD protection required for cables in metal stud walls, what about ceilings?

If you listen to the DJ Sparky on the radio or on Youtube, or some of the other YouTuber’s they are offer the advice that there’s no really an issue if a flat above ground floor doesn’t have RCD protection to any of the circuits at all, as everything can be coded as a C3.


But they fail to mention that supplementary bonding may need to be in place in lieu of RCD protection for bathroom circuits or else you need to raise a C2, so actually rejigging the consumer unit moving one or more lighting circuits to the RCD protected side of a split load consumer unit can be the difference between satisfactory and unsatisfactory.


So if it is the difference between a “pass or a fail” and there’s no other reason why it would be unsatisfactory, it’s a bit of a no brainier, so long as there’s spare RCD protected ways.


Andy B.

KLegh Richardson‍ 


The metal bathroom room window is supplementary bonded.


It’s the Association of Supervisory and Executive Engineers Guide to the 15th edition.


I bought this as a “Saturday night” EBay purchase after a couple of cans, it came from JP’s local library, I do wonder how many forum members have thumbed through it with many having been his students and living in the same area.


Andy Betteridge

Hi Andy,

I now have the ability to log back onto the communities section of this web site.

My name was mentioned with regard to bonding crittall window frames. How may I help?

Legh

Very "of it's time"

Removed a few days ago since I posted this discussion, from above a  metal framed ceiling, the one with the insulation tape is lethal as the live is peeping though the tape.

That's the sort of thing that should be caught by the good workmanship and proper materials kind of rule - we shouldn't have to specify RCDs for that kind of lash up - otherwise we give credence to such practices (there are worse - twisted joints not taped - just staggered, or even three nails driven into a rafter in a barn in lieu of a joint box).

   - Andy,

I totally agree, but I do approach inspecting above metal framed ceilings with great care because there tends to be nasty things above them.

Back when Pontius was pilot, my sainted father (a former sparks turned BTEC electrical craft lecturer) fitted an RCD to the ancestral home, a classic front end job. Final circuit protection was a pair of 3-way MK fused switch disconnectors. Very industrial.


He advised me on the electrical design of my first house, in 1991, and I had two RCDs (rings and lighting) plus RCBO circuits for the fridge and freezer and a separate RCD for the outside supply. This was seen as massive overkill but I reckon was spot on. My current house has an RCD for the ring circuits, then the garage, outside sockets, network cabinet (don't ask) and outbuilding each have separate 1P+N RCBOs (so two-pole disconnect), the fridge and freezer have 1P RCBOs, and the lights and heating are run from a smart home controller that is also RCD protected. I don't cut corners, but in fact the prices have come down so far that this is entirely rational now. I absolutely advocate RCBOs for garage circuits.