what rcd amp size?

[paulthemagpie]

hi,

what RCD amp size to power an outbuilding that has 4 x 2 gang switches, 2 x 1800mm twin florensent lighting, 3 x outdoor flood lights, 1 x multi-gang single pole switch

also im guessing it would be best to have another distrubution board out in the outbuilding?

thanks you for any help that is given

 

[Dean]

What are you actually asking? What ma RCD you should use, Or the size of the MCB used to supply the above? Or what RCBO to use??

 

[Plonker 3]

Do you do any of your own homework? How do you expect to learn anything of you just ask on here without knowing what you are being told?

 

[paulthemagpie]

Do you do any of your own homework? How do you expect to learn anything of you just ask on here without knowing what you are being told?

hello, i take on board what you saying and appreciate it. but im on a home study course and the material isnt that great, so im actually learning more asking these questions then understanding were the answer came from and working backwards.

They is no point as you say to just getting the answers, so i do make sure i fully understand it. The course material is far too technical and just jumps straight in like im already a qualified electrician were as on here you get real answers from real people.

hope you can understand were i am coming from. This forum so far has been fantastic help to me.

 

[paulthemagpie]

What are you actually asking? What ma RCD you should use, Or the size of the MCB used to supply the above? Or what RCBO to use??

hi im asking what size mcd and whats the best set up?

should i just run a mcd to another distrubution box in the outbuilding and if so what size mcd?

thanks for your help

 

[telectrix]

suggest you search the forum for threads regarding supplies to garages/outbuildings etc. there are loads of posts with plans for cable sizes, protection devices etc.

as for you RCD, you would generally fit this in the garage if using SWA and the amp rating would be larger than the design current.

 

[paulthemagpie]

yes it would be using a swa

 

[Dean]

There is no simple answer to what your asking.

Will the sub main be SWA?, if so that can be protected by an MCB. Then in the outbuilding, a new distribution board will be fine, although without knowing what type of wiring systems your using, they will need to be protected by a 30ma RCD.

Again, the size of the MCB depends on load and cable size. Which you will need to do your calcs for.

Then the whole earthing arrangments comes in, is it PME? Is it a suitable' building to export PME into etc..

 

[DPG]

RCD or MCB? Not MCD though. Daz

 

[Plonker 3]

hello, i take on board what you saying and appreciate it. but im on a home study course and the material isnt that great, so im actually learning more asking these questions then understanding were the answer came from and working backwards.

They is no point as you say to just getting the answers, so i do make sure i fully understand it. The course material is far too technical and just jumps straight in like im already a qualified electrician were as on here you get real answers from real people.

hope you can understand were i am coming from. This forum so far has been fantastic help to me.

I understand that you are trying to learn on here, there is no such thing as a daft question is what I was taught at college. But surely looking back at some of your other threads, maybe this course is a little advanced for yourself. I don't mean that in a derogatory way, is there not a level of course beneath what you are doing to help you understand a little more about what you are needing to know?

 

[paulthemagpie]

im fully okay or will be with this course.

ive been fine up to now and looking at all the future units, i think il be fine, but just this particular unit is my weak one. So by getting to grips with this i will be flying again!

 

[DPG]

Have you covered MCBs/RCDs in the course yet, and the function they perform? Daz

 

[Guitarist]

It is one thing to learn some of the theory on a home-study course, but what are you actually planning to do with it afterwards? Are you joining an apprenticeship scheme for the practical experience or just planning to do a few courses at home then go out as an electrician?

 

[paulthemagpie]

no no. i get pratical sessions in house also which are to come later on which will fit alot more pieces together. then after all that it will be out in the work place as a mate and to gather evidance towards my qual.

i would dream of doing a bit of theory then starting as an electrician. lol

 

[DPG]

Sorry to repeat myself, but do you know the difference between MCBs and RCDs and the functions they perform? Your thread starts off saying RCD, then says MCD, and I suspect it should perhaps be MCB?

The only reason I'm asking is that I can't see the point in worrying about sub-boards and whatever if you don't know this. Daz

 

[Dean]

Give the guy a break! He's only trying to learn! We all started somewhere.

 

[DPG]

It's only a question. Just wondered if he knew. Still don't know if he does. Wan't meant to be derogatory. Daz

 

[paulthemagpie]

Give the guy a break! He's only trying to learn! We all started somewhere.

thanks! lol

anyways yet i have covered mcbs, rcds, ect but with the course being home study they expect the material to give me to be a guide and i need to find extra info else were. Such a pain I know.

TBH im not just after the answers i also want to knwo why.

I do spend time working backwards so i understand exactly the subject and im finding that alot more useful as you guys are the experts and i appreciate all the info you tell me.

im not here to leech and can promise to return the favour and hang around and answer other guys questions once i get more knowledgeable and even donate some money to the forum if im getting the help i need!

 

[Richard Burns]

hi,

what RCD amp size to power an outbuilding that has 4 x 2 gang switches, 2 x 1800mm twin florensent lighting, 3 x outdoor flood lights, 1 x multi-gang single pole switch

also im guessing it would be best to have another distrubution board out in the outbuilding?

thanks you for any help that is given

Paul
Just to clarify an MCB (circuit breaker) is a device designed to trip if there is overcurrent or fault current on the circuit it is protecting.
An RCD is a device designed to trip if there is a very small current flow to earth (determined by the difference in Line and neutral currents)
An RCBO combines both the above functions in one device.

When you ask what "RCD amp size" this is not readily answerable as RCDs operate on mA not amps.
RCDs do have a ampere rating that determines the maximum current that they can handle in terms of it flowing through them but this is down to the physical capability of the components to handle this current and is not associated with the protective characteristics.

From your question there is no indication of the total load that would be drawn as switches do not draw current and there is no indication of the power of the flood lights or the fluorescents.

So the question as stated is not anawerable from the information given. We could give an idea of what current handling capability you would require from an RCD on a general lighting circuit but this would not answer the specifics.

 

[Octopus]

Maybe you would get better responses if you stated the question, and your answer, and then see what member think of your solution.