Taking electricity to garage

[3435hobiton]

Hi, I have passed the 2330 levels 2 & 3, the 17th edition regs and also the 2391, although quite new pracitically, apart from college practicals and a little work fitting out log cabins. I am looking at taking electricity to a garage from a consumer unit with no space for my 32a mcb. Would it be acceptable to take a cable from the isolator of the cu to a switch fuse situated locally and then take an SWA cable from there to the garage, where all circuits will be protected by a 17th edition rcd protected cu in the garage?

Regards,

Paul

 

[Zeespark]

New tails from a Henley block. Then new tails into a small consumer unit. What are your earthing arrangements?

AndyGuinness

 

[3435hobiton]

Thanks for your reply. The earthing arranagements are TN-S.

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Should I fit a double pole isolator before the Henley block?

 

[Zeespark]

Nope, that's for the DNO to do, but you can always make enquiries for them to install one, where in the UK are you?

AndyGuinness

 

[Doc Hudson]

For tails that are shorter than 3m there is no obligation or regulation saying you should have an isolator, but having one installed can make life much easier and convenient during future alteration maintenance work. Personally if there is room I would fit one.

Doc H.

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Nope, that's for the DNO to do, but you can always make enquiries for them to install one, where in the UK are you?AndyGuinness

The tails on the CU side of the meter are the property owners, as such isolators can be fitted there at the choice of the owner. Before the meter is the DNO's jurisdiction.

Doc H.

 

[Zeespark]

That's true Doc, this might be over kill, but would 2 DP isolators be the best option here perhaps? to facilitate independent isolation?

AndyGuinness

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And also, what about EAW89 Regulations? not something else to consider?

 

[3435hobiton]

I'm in Paignton, Devon. So would i be right in saying that I split the tails from the henley block, one set going to my existing cu and the other going to my new small cu fitted within the 3mts, housing an Rcd and 32A MCB and then an swa cable supplying a further consumer unit in the garage with my 6a and 16a MCB'S? Also thank you Doc H for the advice.

 

[Zeespark]

Main switch and RCBO's would be a better choice or you would need to install a 30mA RCD after the Main switch.

AndyGuinness

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Is everything going to be surface mounted? if so, then strictly speaking RCD's won't be required.

AndyGuinness

 

[Doc Hudson]

I'm in Paignton, Devon. So would i be right in saying that I split the tails from the henley block, one set going to my existing cu and the other going to my new small cu fitted within the 3mts, housing an Rcd and 32A MCB and then an swa cable supplying a further consumer unit in the garage with my 6a and 16a MCB'S? Also thank you Doc H for the advice.

That sounds like an acceptable solution, just remember not to have two RCD's in series as you will not get any discrimination between the two unless the first one is a time delayed RCD. What is the distance to the garage and are there any extraneous metal parts, (such as pipes, steel supports etc)? Such that you may need to consider separate earthing of the garage? Some members always TT remote buildings, but it is acceptable to export the earth providing certain conditions are met.

Doc H.

 

[3435hobiton]

Yes the cable to the new cu will be surface mounted and then I will be taking an swa cable to the garage. Would you recommend a main switch with 32a mcb and then protect the circuits in the garage with an rcd protected cu?

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or possible a 32a RCBO as you mentioned before?

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The help is very much appreciated!

 

[Zeespark]

Main switch and RCBO is the route I would personally take, how old is the current fuse board?

AndyGuinness

 

[3435hobiton]

Around 8 years old. It is not rcd protected and although I have informed that any new circuits which may supply outdoor machinery etc has to be rcd protected, they are reluctant to have the board changed.

 

[Zeespark]

Is there much space near the current fuse board? the reason I ask is because are you able to possibly install the carcass of a new board, and as the house is rewired in time, the new circuits can be installed into the new board, with the tails being modified at a later date at all?

AndyGuinness

 

[3435hobiton]

This is a possibility, I will have to have another look!

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That is a very good option that did not occur to me

 

[Zeespark]

It would be filled with blanking plates initially, but may save time. Another time saving tip would to remove a small portion of the ceiling where the new cables are to be fed through, it saves having to mess about doing it later.

AndyGuinness

 

[3435hobiton]

Thanks very much for the info, i'll bear that in mind. Hopefully I can get her to reconsider a new board, although I get the impression they wont go for much unnecessary expense.

 

[Zeespark]

A new board carcass, main switch and RCBO won't be mega expensive. Do some checking around online.

AndyGuinness

 

[3435hobiton]

Thanks very much, feel quite a bit clearer now.

 

[Zeespark]

Not a problem bud.

AndyGuinness

 

[3435hobiton]

No extraneous metalwork in the garage. So i'll supply the distribution cable to the garage with a 32A RCBO and then fit the garage with just a 100a isolator and the 16A and 6A MCB'S.