Some advice on good practice please. I need to replace the 6kW shower that my father fitted about 30 years ago, and I'd rather like an RCD to protect my hide when using it. I looked in the meter cupboard, and didn't like what I saw. There's a 100A company fuse, an 80A meter, an 80A old black bakelite Wylex 8 way CU with 80A switch and cartridge fuses, and what look like 60A cables from the company fuse to the meter and 80A from the meter to the CU. I guess I should get the company to replace their cables. Should I expect a new meter too? I see this estimable company selling a Volex 80A RCD at a nice price. If I had an 80A fuse, I could wire the meter tails to the RCD and thence to the CU and have everything protected. However with electric cooker, shower and if the gas is off 3kW fire and 3kW immersion heater, 80A looks marginal, and the company fuse is 100A. Should I just shell out for a 100A RCD, significantly more expensive? The alternative is a new 8way CU with 100A switch and MCBs. Here's where the fun starts - I see most come with a smaller RCD rating than 100A. Is the trick is to split the circuits, with some outside the RCD's protection and others within, or do I just say "diversity" and stand clear? What's normal practice? Thanks in advance.
My advice Greybeard..(for what its worth)..get a Sparks in with a view to fitting a nice split loader DB..while the sparks is there get him to fit an isolator near cutout (maybe your DNO might do this free if they decide that the meter needs changing).. If a sparks fits a new DB then he will test circuits and carry out tests generally before commissioning the DB.. And issue certification when everything is deemed ok.
Yo - from your questions, Greybeard, you don't sound like you know enough yet to be getting into replacing CUs...
> CU, also known as consumer unit or fuseboard. My prefered/correct term is DB, AKA Dis-Brd, AKA Distribution Board. CU = Cooker Unit!
Yo - from your questions, Greybeard, you don't sound like you know enough yet to be getting into replacing CUs... has he suggested he was going to do this work himself or are you just guessing again BAS
My advice Greybeard..(for what its worth)..get a Sparks in with a view to fitting a nice split loader DB..while the sparks is there get him to fit an isolator near cutout (maybe your DNO might do this free if they decide that the meter needs changing).. If a sparks fits a new DB then he will test circuits and carry out tests generally before commissioning the DB.. And issue certification when everything is deemed ok. No such thing as a 'nice' split loader db. As far as i am cocerned they have never met BS 7671, 314-01-01
am cocerned they have never met BS 7671, 314-01-01 In what respect Slip..only interested as have fitted tons of the things..Wylex before using my first Starbreaker Split Loader DB a while back..
<u>I'd</u> rather like an RCD... <u>I</u> see this estimable company selling a Volex 80A RCD at a nice price. If I had an 80A fuse, <u>I could wire the meter tails to the RCD and thence to the CU</u>... Should <u>I</u> just shell out for a 100A RCD... The alternative is a <u>new</u> 8way <u>CU</u> with 100A switch and MCBs. Here's where the fun starts - I see most come with a smaller RCD rating than 100A. <u>Is the trick is to split the circuits, with some outside the RCD's protection and others within</u>" The last question particularly is indicative - why would he want to know that if he wasn't planning on installing the new CU himself? And in general why would he be looking a different CUs, and asking what to buy, if he wasn't planning on installing it himself?
I'll leave the lot alone, and fit a separate 30A RCD for the shower. Trouble with asking a commercial sparks to fit a new CU is I'll get a quote for several grand for complete rewiring and follow-up replastering. All I actually wanted was like my home setup where I replaced the old CU with a Wilex with 80A RCD and 8xMCBs, nice and tidy, it's a 60A company fuse and cooking by gas. That was when you could do it yourself. But the 100A fuse worries me on this installation, though at least this one's earthed via the company cable's sheathing, unlike home, which is overhead cables and an earth spike. I'm surprised nobody seems to sell a CU with a 100A RCD fitted. I know that none of the cowboys come here, but my experience with pros has not been good: the one who installed my boiler, and said "don't switch it on until I've checked it tomorrow - I'm a bit worried that I've got a red and a green wire going to the same terminal" - he's misunderstood Honeywell's wiring diagram. Or the one that installed the new CU in my mother-in-law's house, and wired the lights to 16A MCBs. Or the electricity board bloke who fitted the 100A fuse without changing their meter tails when my father installed the shower in the first place. Or the rather more professional bloke who did my garage (nothing wrong with the wiring and workmanship), but why did he fit a 6-way CU and charge me over £100 for it?
If you don't have a shower, cook and run fan heaters all at the same time - probably not. 60A is 11.5KW, enough to run quite a few appliances. You shouldn't change a DB unless you know what you know exactly what you are doing. Can you check insulation resistance (in effect pressure test the existing wiring) and be sure that everything is earthed properly and will disconnect automatically within the prescribed time in the event of a fault? Get a sparks in and if he seems too keen to upsell, try another. If your installation is safe, a good sparks will change the DB for £500-700, test the installation and make good any minor problems.
and how do you know that you have a 100A fuse installed in the 100A fuse holder, in my region the distribution company rarely fit bigger than 80A (although the carrier may have a 100A sticker?
most people don't make db's with 100A RCD. as most of them are split loaders now. Put sockets, shower on rcd side. Put water heating, lighting on non-rcd side. Get a sparky in to do it for you. The main advantage of split loaders is that if the rcd trips, then you can still find your way as the lights are still on!
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