advise please -Consumer Unit MCB choices for detached garage

[portera]

Hello first post here, although been a browser for a long time.

I'm feeding detached garage for a couple of sockets and lighting. Got a small module for garage - 16a mcb for sockets and 6a mcb for lights.

Problem - Consumer unit in the house is dual RCD. Both 63a RCD. One is running 32a (cooker), 16a (boiler) and 6a (upstairs lights). Other is 32a (sockets) and 6a (downstairs lights).
Can I run garage from a 16a mcb on the CU (taking RCD load to 54a) and can that then supply the 16a and 6a mcb's in the garage? Or could I take a spur at the mcb from either the boiler or cooker?

The sockets in the garage will only run a tumble drier in winter and lawnmower in summer. Lawnmower willl be plugged into an RCD protected extension reel.

Only other alternative I can think of is to run just a 16a mcb in the garage and run lighting from a plug socket like a bedside lamp.

Thanks in advance.
Andy

 

[riveralt]

Hello first post here, although been a browser for a long time.

In which case you will be aware that, if you are located in England or Wales, what you propose is illegal unless you have notified you Local Authority Building Control,
paid their fee and shown them how you intend to compentently design, install, test and certify that the work meets current standards.

The questions that you are asking clearly indicate that you do not have that knowledge or competence. The best advice I can give you is to hire an electrician.

This work is beyond most Diyers.

 

[AndyPRK]

it depends on the size and length of cable going to the garage.

But fitting a 16A MCB into the CU is the best guess

 

[ban-all-sheds]

You haven't said how far it is to the garage - have you considered voltage drop and EFLI when sizing the cable to it?

What route will the cable take?

Have you decided what is the most appropriate type of cable?

Regarding the new final circuits in the garage, do you know what tests you would carry out on them - what sequence you'd do them in and at what point you would energise them? For each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

Why would you want to use an RCD extension lead on a ciruit which is already RCD protected?

Re riveralt's comment about knowledge and competence I would observe that you don't know about discrimination between protective devices, nor the rules for spurs.

The thing is, installing new CUs, outside supplies, submains etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

• //www.diynot.com/wiki/electrics
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• http://www.tlc-direct.co.uk/Book/1.1.htm[/list]I suggest you get stuck into the last link right away - it won't give you design ideas, and unfortunately it doesn't refer to the current edition of the Wiring Regulations, but it's free, and will still give you a good grounding which you can augment with more up to date publications.
  
  
  
  Or get an electrician.

 

[Taylortwocities]

And where is the discrimination of the mcbs?

There is no dicrimination if you have a 16A MCB in the house and another 16A MCB in the outbuilding.

Is there a reason why you chose a 16A MCB to feed this cable? What is the CSA of the cable?

ALso
Does your propsed fusebox have an RCD? If so you do not need it, there's already one(two) in the house.

 

[riveralt]

........ But fitting a 16A MCB into the CU is the best guess

You shouldn't be advising people doing electrical diy work to guess