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DIY Forum >> Electrical Questions >> Which mcb rating for which cct? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1100736908 Message started by nyck on Nov 18th, 2004, 12:15am |
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Title: Which mcb rating for which cct? Post by nyck on Nov 18th, 2004, 12:15am I bought a MEM 14 way splitload CU complete with MCB's about 18 months ago.I had a few delays with my extension but now at a stage to fit the new CU.Beacuse it's been so long i've lost the list what mcb's for each cct.I got the info/help from E-Build forum but they have changed the forum and the info is no longer on the site ,so need advise. The MCB's i ordered are 4x6A 3x16A 7x32A Up lights =6A down lights =6A Up ring main 32A down ring main 32A Kitchen(fridge,Dishwasher,sockets)=? Utility room(Boiler,Freezer,washing machine,tumble dryer)=? En-suite(electic shower,extractor fan)=? Bath room(extractor fan)=? conservatory=? garage=? Shed+outside socket=?(This cct can be linked to garage cct if more suitable) I can't remember where i would use the 16A mcb's Also in the kitchen+utility would it be better to keep the (Dishwasher, washing machine,tumble dryer,sockets)on the RCD side and the boiler,fridge,freezer on the normal side. thanks nyck |
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Title: Re: Which mcb rating for which cct? Post by L.Spark on Nov 18th, 2004, 12:47am wrote on Nov 18th, 2004, 12:15am:
Hey Nyck Well e-build is a bit of a dead loss to be honest, thanks for coming here :) MEM is a good brand, you sound like you have it all pretty much worked out ok actually. Kitchen if it's a radial of it's own e.g. not a ring, and is wired in 2.5mm can be rated at 20A, or 16A if you can't change the breakers (best to swap a few though) Utility room - The same, if you have not already wired the circuits a ring circuit just for the kitchen is a good idea, if the utility room is close this could share the ring, however radial circuits are better for kitchens and utility rooms, 20A again if wired in 2.5mm cable electric shower - This should be wired on it's own, and the Rating of the MCB will depend upon the power consumption of the shower (more info needed e.g. rating in kW) Extractor fan - this can be wired from your lighting circuit depending on it's load, but usually it's no problem, it would need a local isolation switch and fuse (Fused Connection Unit [FCU]) conservatory - What are we talking about exactly, Lights/Sockets etc garage - What cable is supplying the garage, as the breaker size is directly responsible for protection the cable... Shed+outside socket - This wired from the garage, would need to know what cable is to be used again, 2.5mm should be big enough for your average shed use, 1 socket & Light etc, however please bare in mind Volt Drop ( VD ), this must be considered on all cables/sub mains, this for the garage and also the shed, the longer, the cable the bigger it will need to be if you plan to run allot from the cable. 16A MCB's are usually for radial circuits like the boiler, and also the immersion heater/water heater, or other heater if you have one Quote:
All sockets should be on the RCD side of the board, assuming it's a split load board. If the dishwasher has it's own radial circuit, this could supply Fused connection units which control each piece of equipment individually The boiler can be on the NON-RCD side of the board, along with the freezer and fridge, however you plan to connect these. Hope this helps |
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Title: Re: Which mcb rating for which cct? Post by nyck on Nov 18th, 2004, 4:04pm Thanks for the quick reply.I agree about e-build there to many headings and sub-headings and screwfix if your post dosn't get answer in a few hours your post goes off the page. Some good info in your post,i'll plan my electrics and post again what i have come up with a plan I will be replaceing the exsiting wiring eventully in the whole house thats why i need to plan ahead and take it as new install. Good news about the extrator fans of the lighting Conservartory will be just socketsx3 and lighting garage+shed will be just lights+sockets DIY tools etc not welding etc shower is 8.5Kw 6mm cable i put in a temp 32A MCB and its never tripped so i was going to use the same valve MCB? i've just started to plan but head hurts will be back later with my ideas thanks nyck |
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Title: Re: Which mcb rating for which cct? Post by sparkyjonny on Nov 18th, 2004, 6:53pm Your 32A breaker is being overloaded slightly at the moment - it may not trip but it's not ideal design practice. Replace with a 40A breaker. 10mm cable would be nice for the shower if you get a chance to run a new cable - 6mm is ok for your existing unit, but limits any future shower to a low power rating. |
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Title: Re: Which mcb rating for which cct? Post by L.Spark on Nov 18th, 2004, 10:09pm Ok nyck Well were here to help when your ready Planing ahead will be essential, bear in mind cable routes, routing cables in safe zones that comply with regulations is important. The breaker on the shower at the moment probably wont trip until you reach maximum heat setting which is unlikely, however it would be a good idea to upgrade that even for the short term as SJ suggested. 10mm cable would also be reccomended for the shower installation for future proofing as SJ suggested. Get us to check your plans before you commence any work so if theres any possible problems we can point them out to you before it might be too late 8) |
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