Discuss Critical feedback request - Consumer unit. in the UK Electrical Forum area at ElectriciansForums.net
Bites tongue........Oh no! The BBC will be round to sort that......
I'm freshly back.
Reg 421.1.201, item (ii) refers to using a enclosure made from combustible material to be installed in a cabinet or enclosure made from non combustible material, i.e. comply with (i) or (ii).
MythBreakers videos - https://www.hager.co.uk/news-exhibitions-case-studies/news/amendment-3-to-bs-7671-2008/mythbreakers/56067.htm?mainvideoid=6dnZNI0bzRk
Unless they have changed the reg again in the 18th (I only have the BYB), there is no requirement to use intumescent seals in a CU made from non combustible material, only to maintain the IP ratings as per reg 416.2.1 (BYB). I don't believe the back of a CU requires this rating, although if someone could access the back, it would make common sense to maintain a similar IP rating.
Reg 421 etc actually says it shall "be enclosed in a cabinet or enclosure", I don't view having a large hole at the back as being 'enclosed'.
That video only stats that Hager, have done the tests, it doesn't cover all CU manufacturers, and he actually ends by saying "you may need to use some of these to maintain IP standards" (Intumescent seals etc.)
Normally I would totally agree with you but it's the fact that the material behind the hole is highly combustible i.e. wood and you have to consider External Influences i.e. BE2 - Fire Risks, characteristics required for 'erection' are equipment made of material retarding the spread of flame. Air, comprising that opening doesn't comply with that.
and CB2 - Propagation of Fire; erection characteristics required are Fire barriers, again air and wood aren't a fire barrier.
There's quite a large stand off gap between the CU and the wooden back board; if there was a fire in any of these CU's they're installing, air will get sucked in from around the CU and they'll be a blow torch effect out of the back of this hole, onto the wood, but if you still think that it complies and is no risk because the rest of the case is made of metal, then so be it.
Reply to Critical feedback request - Consumer unit. in the UK Electrical Forum area at ElectriciansForums.net