Electric For New Shed

[RPOY]

Hello to you all at DIYnot,

Ive just got a new log cabin shed, the shed is 150ft down the garden.

Now i want to add eletric to it, ie, lighting, sockets. Just want a simple set up.

Just a few question.

What i was thinking of getting done was, runing twin and earth (protective of course) down the garden coming of a socket, ie spur. But Im not to sure how far you can run 2.5mm twin and earth from a spur

But what i really want done is a consumer unit in the shed, all I need is a 6amp for the lighting and 32amp for the ring main. to do this I would have to use either run single earth live and neatrual 6mm or more, (protective of course) or which i think is the best idea is to use SWA.

By question is, how hard is it to add a second consumer unit and where can I pick the power up.

I'm not a eletrisain but am happy to do this install myself because ive done a simliar install before, but not to a scale of runing cable 150ft and not even touched a subject to adding a seconed consumer unit.

I know im gonna get a lot of stick and can see ppl saying u shouldnt do this yaself I fully understand what you are saying, and if I feel that it really not safe to do so, then I will step back.

What I want to know is how simple it can be in adding a second consumer unit if its to hard then an expect will have to come in, but as ive said before i feel conficant in doing the rest.

I'll be buying all my equipment from screwfix



Any advise is very much appreitanted.

thank you

 

[mo2]

Any advise is very much appreitanted.

i found that funny


anyway, as far as I understand according to Part P of the building regs you can not add a second consumer unit or electrics outside without certification AND STUFF

 

[RPOY]

I wont hit back on the coment u said, coz im just looking for information

I was looking to install somethink very simlar like this

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331827&ts=49262&id=63138#

As for the consumer unit, ok i may need to get some1 in (as I said in my first post)

If its gonna be to much trouble, then I would like to know how far I can run a spur?

 

[securespark]

You want a ring final & a lighting circuit 150 feet away on a spur?

Nah...

 

[Steve]

And its not a matter of safety or confidence, its a matter of compliance with the law. We can talk you through it step by step on the forum, however it doesn't get around the fact that you haven't notified your LABC under part p of the building regs. Get onto building control and ask for their opinion on whether it is best to get an electrician in.

For that distance, you'd probably need a 10mm² armoured cable for a 32A submain to the shed. Though I dont know how to work volt drop out for an exact figure.

If I were you, i'd go the whole hog and run 16mm² armoured, this way you've got room for expansion. After all, you dont want to dig the trench twice.

 

[RPOY]

I dont need to run a spur no more, just been under the stairs and there 3 spear fuses i could use.

Now all I want to know is the size of cable in mm (twin n earth) I'll hav to use if i'm runing 150ft (50m)

 

[RPOY]

You want a ring final & a lighting circuit 150 feet away on a spur?

Nah...

No not at all, just a ring final, that way I can just add a socket and a plug light, Not a light circiut from the spur.

 

[dingbat]

I dont need to run a spur no more, just been under the stairs and there 3 spear fuses i could use.

You only just looked?

Now all I want to know is the size of cable in mm (twin n earth) I'll hav to use if i'm runing 150ft (50m)

You want to use twin and earth?


You really shouldn't be considering doing this yourself.

 

[RPOY]

I dont need to run a spur no more, just been under the stairs and there 3 spear fuses i could use.

You only just looked?

Now all I want to know is the size of cable in mm (twin n earth) I'll hav to use if i'm runing 150ft (50m)

You want to use twin and earth?


You really shouldn't be considering doing this yourself.

Sorry ment to say SWA

 

[breezer]

you still should not do it your self, part p and all that, and if you actually read everything posted you would have found your answer.

and what is a spear fuse, is it a pointy one ?

I dont need to run a spur no more, just been under the stairs and there 3 spear fuses i could use.

 

[Taylortwocities]

The wise owls (above) give you good advice. Looks simple, it isnt. Lots of things to consider.

But I'll try and be helpful. Have a read of this while you are waiting for the £700's worth of multi-function test equipment to arrive.....

http://www.iee.org/Publish/WireRegs...matters_electrical_installations_outdoors.pdf

TTC

 

[Steve]

come on lads, at least give him some idea of the scope of work involved here. I mean, if we dont tell him, he might go ahead anyway, do it wrong, and kill himself.

 

[Big_Spark]

Lets attack this from an intelligent point of view rather than mocking..although it is tempting for a laugh!!

The shed is 150ft from the house, so lets assume 170ft (57m) of cable would be needed to supply the shed.

You will run a Ring in the shed, possibly a heater due to distance, as well as lighting, so lets assume a TOTAL POTENTIAL LOAD of 30A.

Now lets do a quick calculation.

2.5mm² SWA is rated at 36A and has a volt drop of 19mV per A per m

So... 19x30x57/1000 = 32.49V

This is no good as the maximum volt drop is 9V

4.0mm² SWA is rated at 49A and has a volt drop of 12mV per A per m

So.. 12x30x57/1000 = 20.52V

Again no good.

10mm² SWA is rated at 85A and a volt drop of 4.7mV per A per m

So.. 4.7x30x57/1000 = 8.037V

This is just inside the compliance required and would mean that the load at the other end could not safely exceed 30A.

Now perhaps you see why this seemingly simplejob is perhaps a little outside your abilities.

Due to the distance from the source of energy the cable MUST be buried, or suspended a minimum of 3.2m from the ground, and if buried it MUST be in a duct with warning tape between it and the surface.

The installation should be protected by a suitably rated circuit breaker at the supply end (32A Type B MCB). Personally I would install a 300mA Double Pole Type S RCD, but this is NOT a requirement of the regs, simply good practice, especially due to the distance from the shed.

However the end terminated in the shed MUST be RCD protected and it should be a 100mA Type S RCD as a minimum. The Ring and any POWER circuit should be protected by a 30mA RCD(RCBO).It is your decision as to whether to pay the extra for individual units or simply protect the whole shed with a 30mA DC sensing RCD.

On top of this the entire installation would need ot be tested and inspected and a certificate issued from a recognised and registered contractor for the local planning office.

It would be cheaper for you to get a contractor to do the work for you as they are required to test their work upon completion and issue a minor works certificate.

You could dig the trench for the cable duct yourself and save some money that way.

Oh..steer clear of that cheap rubbish on the screwfix website..for what you want you need good quality equipment and you want to avoid Volex, Proteus and similar cheap gear.

 

[Steve]

Excellent reply Big_Spark. However, there is still no need whatsoever to protect the cable using an RCD. The MCB gives it all the protection it needs.

And you forgot about the issue of exporting earths, particularly the PME variety, however, I doubt his new log cabin has any ECPs.

RPOY, what variety of earthing system do you have? See the WIKI to figure this out.

 

[Big_Spark]

Crafty, that is why I said it was personal choice..and personally I would be very inclined to do if the client were willing to pay the cost.

It's simply a matter of safety should some twonk dig the cable up or the RCD at the shed end fail for some reason.

If you use SWA then the Building Earth can be taken to the Shed as your simply installaing a sub-main supply, this is regardless of the supply type from the DNO.

I'm sure that someone will come along declaring "install a Rod" from the rooftops, but I have had this discussion with the IEE, the NICEIC and various DNO's. So long as the Earth is continuous and unbroken, there is no requirement to install a rod or secondary earthing, only the required supplementary bonding if required at the other end.