Observations From France

[Marvo]

It is not unusual for me to install a 54 way CU in a 3 to 4 bed house, infact the last one I did a few weeks agr was a 72 way with 4 RCD's

You are joking I assume. I also live in a land where 20A 2.5mm radial circuits are the domestic norm. A normal 3 bedroom house with all the usual appliances would require 3, or maximum 4 radial ccts for sockets, also a dedicated radial for immersion heater and maybe another dedicated radial for swimming pool and/or garage. If you include 2 lighting radials (one upstairs and one downstairs) you're looking at a 12-way DB including main and RCD, 16-way will have plenty of future proofing. If you install a 54 way box you'd have at least 40 ways spare.........a 72 way would have 60 ways spare, handy if you need more cupboard space or somewhere to conceal your gun safe maybe

 

[overskilled]

I could see 32 possibly if its DP MCBs.... (2 ways each)
72 though....how big a house are we talking? :/

 

[Marvo]

D/P MCB's sometimes only take the same space as a single pole

 

[overskilled]

I realise that Marvo
I was just looking at a worst case scenario...

 

[Engineer54]

You are joking I assume. I also live in a land where 20A 2.5mm radial circuits are the domestic norm. A normal 3 bedroom house with all the usual appliances would require 3, or maximum 4 radial ccts for sockets, also a dedicated radial for immersion heater and maybe another dedicated radial for swimming pool and/or garage. If you include 2 lighting radials (one upstairs and one downstairs) you're looking at a 12-way DB including main and RCD, 16-way will have plenty of future proofing. If you install a 54 way box you'd have at least 40 ways spare.........a 72 way would have 60 ways spare, handy if you need more cupboard space or somewhere to conceal your gun safe maybe

If you look in the non-UK Forum, the French spark (forget his name now) posted a photo of a typical domestic French DB, and from what i remember it was very much along the lines of what Victor is saying. Also the French make use of pulse relays quite a lot on lighting circuits, which also adds to the space required in any DB, ...not forgetting the i think obligatory DB Din rail mounted socket outlet!!

I can remember a hospital project in Saudi many moons ago that included staff villas and the like, where the electrical spec was based on French installation standards. Believe me, i'd never seen domestic DB's of the size used on that project. MCB's RCD's and those pulse relays galore!! lol!!

 

[Victor]

The main problem here is that the required number of RCD#s depends on the size of the property, so for a house over 100sqm the required number is 4 of which one would be a type A and the rest type AC. When you combine that with only 8 sockets per circuit and 8 lights per circuit then you really start to fill up a CU.

Regulations also state here that for a new installation or a renovation you must leave 20% of the cu free for future expansion and that you must install 2 x sockets in the cu, it does not take a lot to fill up a 54 way board and if you have electric heating the a 72 way is easy to fill.

 

[Knobhead]

Always thought the French were crazy. Now I know.

OK DP or SP&N switching makes sense. We should adopt it. I do like latched relays for lighting.

No way would a house warrant a 72 way board.