Garage power (groan!)...is this ok?

Multiplex · 26 May 2005

I know there's a million threads on garage power as I've just been reading them all!

Am I ok using this RCD Spur from TLC off my kitchen ring main using 2.5mm 3core SWA?

http://www.tlc-direct.co.uk/Products/CM4904.html

The garage is only 4 metres away and I only need to power a light and a lawnmower at the same time, but I guess with the RCD Spur I can put whatever I like in the garage without having to worry about it...

Sorry for posting another garage thread btw!

Simon.

ban-all-sheds · 26 May 2005

How do you propose to terminate the SWA in that?

What do you plan to do at the garage end to create a lighting circuit and a socket circuit?

I assume that your kitchen ring is not already RCD protected?

Multiplex · 26 May 2005

I was going to terminate the SWA in a metal box in the garage and leave the tails of the SWA long enough to take it into the 13A RCD Spur.

After that I was guessing that a junction box would be sufficient to take wires up to a switch and a light as well as feeding a socket in the garage.

The kitchen ring is on an MCB but there's a few threads here with people insisting that an RCD is needed in a garage and this RCD 13a/spur from TLC seemed perfect.

Simon.

BJS_Spark · 26 May 2005

The RCD is needed not because it is a garage but because it is feeding appliances outside (Outside of the equipotential zone) like the lawnmower.

The RCD should be placed on the ring in the kitchen at the start of the circuit with a 13A fuse in. At the garage end I would use a normal switched fused spur for the light with a 3A fuse fed from a JB which spurs off to the socket.

The SWA needs to be buried 450mm deep with a warning on top of it to show diggers it is there.

You may wish to re-think with a larger supply option for future proofing if you may run more equipment in the garage as people often do once the supply is in. (ohh I just think I will stick a tumble dryer in the ol' garage!!)

Multiplex · 26 May 2005

How do I get the RCD fitted in the kitchen?! And why does it have to be in the kitchen when the garage is only 4 metres away?

Simon.

Steve · 26 May 2005

you should run 2.5mm t+e from the RCD FCU to a metal adaptable box, to join to the SWA, as it will be very difficult, if not impossible, to terminate SWA in a standard back box. Fit a similar box in the garage, and carry on there in 2.5mm t+e. Should only fit a couple of sockets and a light (on seperate 3A FCU) though, or theres a risk of blowing the fuse in the FCU if someone plugs in a couple of big power tools etc.

but I guess with the RCD Spur I can put whatever I like in the garage without having to worry about it

please explain what you meant by this. you can still overload the fuse in the rcd spur. the rcd doesnt stop overloads.

ban-all-sheds · 26 May 2005

I don't like the idea of the lights in the garage being on RCD.

I'm not entirely convinced that all circuits outside the equipotential zone need RCD protection - only those supplying portable equipment outside the zone. At 4m I don't see how EFLI would be so high that you'd need an RCD for 5s disconnection.

Unless someone can convince me that all of the circuits need RCD, including the buried cable, I'd say put the RCD protection at the garage end, in the form of an RCD socket outlet or RCBO. Spur off the ring in 6mm² to the adaptable box, run 4mm² 3-core SWA (L/N/E but also earth the armour), or even 6/10mm² for future proofing, to the garage. Instead of messing around with FCUs, install a mini-CU for lights & sockets, and either use an RCBO for the sockets, or RCD socket outlet(s).

Multiplex · 26 May 2005

I'm sorry to ask a stupid question now, but I'll do it anyway.

I know that a spur mustn't take more than 13A, so the TLC 13A RCD Spur I thought was very good, does it not prevent the spur from going over 13A?

If I put a mini CU in the garage, like this one:

http://www.tlc-direct.co.uk/Products/TLBS16slash6.html

What's to stop the spur from going over 13A as per ban's layout?

Simon.

ban-all-sheds · 26 May 2005

It's only spurs wired in 2.5mm² that need to be limited, to prevent the cable being overloaded.

Multiplex · 26 May 2005

Ahhh, okay. That explains that! I'll go ahead with what you suggested and will post back when it's finished.

Many thanks,

Simon.

ban-all-sheds · 26 May 2005

In your trawl of a million threads, did you come across any mention of Part P?

Multiplex · 26 May 2005

Hang on a sec...you didn't think I'd be doing it myself did you?

Simon.

ban-all-sheds · 27 May 2005

Well.... it's what you said....

Multiplex · 27 May 2005

You shouldn't jump to conclusions. At what point is the Part P threshold crossed when an uncertified electrician does the hard work and leaves the certified electrician to finish the job?

It MAY surprise you that some people come on here to find out how a job should be done PROPERLY, even by qualified electricians! Last year you guys helped me with my electric shower, and when the electricians came to quote one wanted to install 6mm cable (on a 20 metre run) and the other said RCD protection wasn't really needed!!!

My neighbour (with the same house) has had her garage wired up a couple of weeks ago by an elderly electrician who charged her 60 quid. It's a spur on SWA into her garage, and there's no RCD, CU or anything!! Is this what I should do? I think not!!

So before every thread ends with "Do you know what Part P is..." I just want to remind you that you guys help a lot of people know and understand how to do a job PROPERLY, and that without help and advice here it makes it even easier for electricians to get away with whatever they want.

Besides, if you have garage electrics put in wouldn't you want to know how it's supposed to work before getting it done?!

Simon.

ban-all-sheds · 27 May 2005

Hey - don't get all bent out of shape.

Firstly, it's no concern of mine whether you comply with the Building Regulations or not - I just wanted to make sure that you knew about them, that's all.

And secondly, I did not jump to conclusions:

ban-all-sheds said:
How do you propose to terminate the SWA in that?

Multiplex said:
I was going to terminate the SWA in a metal box in the garage and leave the tails of the SWA long enough to take it into the 13A RCD Spur.

then a few of us said:
stuff on installing cables, and what accessories to use where

Multiplex said:
I'll go ahead with what you suggested and will post back when it's finished.

If you are planning to have an electrician take ultimate responsibility for this work, then you should not have been asking questions here, and settling on a design, and installing cables and accessories, and terminating SWA, without his involvement. You should have found an electrician, got him to do the design, and asked him what parts of the work he was happy for you to do. With your plan, at what point did you think you'd be handing over to an electrician saying "OK - you can take it from here and sign on the line to say it's all your own work"???

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Garage power (groan!)...is this ok?

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