Given that our hosts and their competitors don't seem to sell CUs prepopulated with RCBOs, I'm looking for the most cost effective way of buying, say, a decent 18 way metal CU with: 100A DP mains isolator SPD 10 RCBOs (1 x 50A, 5 x 32A, 1 x 20A, 3 x 6A) 4 blanks for future expansion Where would be the best place to buy something along those lines? Before any of the pro sparks suggest I leave this to my spark to buy, he'd rather not have to buy it himself because he is just below VAT threshold so prefers it purchases like this go through his customers' books rather than through his own.
Got mine from Link, made an error, all the RCBO's said type B on box, but turned out to be curve B type AC.
Screwfix sell all RCBO consumer units BRITISH GENERAL 12-MODULE 8-WAY POPULATED MAIN SWITCH CONSUMER UNIT (640FG)
Thanks. Unfortunately that's only 8 RCBOs and being 12 way, there is no space for the remaining 2 RCBOs that I need and for the 20% spare capacity usually required in a new CU install.
That looks good, and seems to be a great way of configuring it. Unfortunately they don't seem to have any SPDs. I'll give them a call in the morning.
I've seen that exceedingly annoying mix-up of MCB curve and RCD type as well. Makes finding devices a PITA. Full marks to the fools who decided to create the possibility for that confusion. Can you actually get type B or type F RCBOs?
I asked a similar question twice of the "experts" on Voltimum 18 months ago and still havent had an answer.
I use Contactum boards from TLC-Direct. 16 Way Metal Consumer Unit - 100A Main Switch (tlc-direct.co.uk) Putting your requirements into my CU planner gives a 16way board with main switch, SPD, 10 RCBOs (B Curve type A), tails gland and tails = £270.69.
Surprisingly the spark suggested BG. My only experience of BG was when I bought a fully populated 10 MCB dual RCD metal CU from our hosts a year ago, only to find that the MCB arrangement didn't match what they said on the box, and one of the two RCDs failed the time test when the spark that installed it came to testing it all. (This was a different spark from the one who is insisting on a new CU after a few too many C2s in an EICR he performed last week.)
Hi Thanks for your enquiry and Type B RCD’s have quite a bespoke application and, at the moment, our technical constraints do not allow the device to be compact enough to be in an 18mm modular width Therefore, you would need to use an mcb in conjunction with the RCD to provide this application to your circuit With best regards, Darren Electrium Sales Limited SI LP ELEC S BD Walkmill Lane Cannock WS11 0XE, United Kingdom Tel.: +44 1543 455000 Fax: +44 1543 455001
I did wonder if that might be the case with Type B (and F). Maybe we should prepare ourselves for CUs to get a lot bigger, to allow 2-module devices. At least the opening up then of the possibility of 2-pole busbars would make wiring simpler.
Do you really need four spare ways in a consumer unit rated at 100 amps in addition to circuits with a total capacity of 248 amps? What size is the suppliers fuse?
The current CU contains 10 MCBs and I'd like to replace each of them with an RCBO of the same overcurrent rating (as per the above list). The mains isolator takes 2 ways. The SPD takes 2 ways. That's 14 ways minimum. General guidance for the installation of a new consumer unit is to allow for 20% more circuits to be added; so 2 more ways required/desired in my case. I'd like a minimum of a 16 way CU to achieve the above. The main fuse is currently 100A, but the tails are 25mm2 so capable of more than 100A if ever the need arises for that ... not that that is likely. However, without spare ways what do I do if I suddenly decide I want to install a charger for an electric vehicle, or power a shed off its own circuit? I don't plan on drawing anything like 248A at the same time, but I don't know of a single house I've ever owned or worked on where all MCBs add up to be less than the maximum current rating of the RCD protecting them, or even the (usually 100A) mains isolator. If you are a professional spark and a customer asks you for 4 main ring circuits (upstairs sockets, downstairs sockets, kitchen sockets, annex sockets) each with their own 32A MCB, would you tell them they can't do that because they'll be exceeding their two 63A RCDs and their 100A mains isolator. I'm pretty certain every CU you have ever worked on has more current carrying capacity in the MBCs than catered for in the RCD(s) and mains isolator.
In my house the DNO fuse is 60 amp, so a 63 amp RCD would be fine even if feeding MCB's with total of 400 amp. With caravans I have seen a 10 and 6 amp MCB with idea your MCB should trip before the sites 16 amp, but with a house never seen it arranged so your trips will always fail before the DNO fuse. The CU type testing means 125 amp max, in real terms 100 amp, if you need more than 100 amp, then either split phase, or three phase, even with old economy 7 two independent supplies with 100 amp each, never seen a domestic with over a 100 amp DNO fuse. I have not seen a CU with a smaller than 100 amp isolator, the RCD may be 63A, 80A or 100A, but isolator always 100 amp, and you will not have any RCD's so that does not matter. As to electric vehicle, it seems to get better than type A RCBO you need more than one slot, so very likely will need some sort of RCD or DC detection built into the charging pod, so often not fed from consumer unit anyway.