Another Garden shed wiring project.

[SuperKat]

I am about to erect a new metal garden shed and take down my 20 year old cow shed. My existing shed is wired with twin and earth buried in pipe below slabs. It is spured of an exisiting socket in the house. The consumer unit only has 3 fuses 1 for cooker 1 for lights and one for ring main.

I am guessing I am going to need a new consumer unit for starters. Is there an alternative? Could I for example replace the ring main fuse with a larger one and rewire the ringmain and shed into one of these: http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331827&ts=49841&id=63138 Or is there a better way?

I intend to do the majority of work myself to lower costs and have it certified/notified/checked by a qualified electrician.

The shed curcuit will only power a few power tools, garden pond, shed lights and garden lights.

I know I will need SWA cable, but not sure what size? 1.5mm, 2.5mm or 4mm and 3 or 4 core?

How are these connected at each end? I guess I need a n RCD in the shed?

Any help or links to guides would be appriciated.

 

[Steve]

A metal shed? oh dear. This will probably introduce issues involving exporting earths.

Please post a picture of your mains intake (meter and main fuse, showing as much as possible). Only having 3 fuses - you might need a full rewire, as well as the new fuse box!

You shouldn't increase the rating on that ring main fuse. You probably cant anyway, the fuse box may not accept bigger ratings than 30A.

That mini-CU you linked to is OK for fitting AT the shed - for lights and socket circuits.

Get an electrician to come and advise BEFORE you start work - dont just expect any spark to sign off your work - he is putting HIS name to YOUR work, most reputable sparks wont do this. When he arrives, ask him about earthing arrangements and exporting PME earths - astonish him with your knowledge of tech. terms, he will be less likely to BullS*** you.

 

[diyunotaclue]

dont even need to look at this to know it needs complete rewire my friend, maybe the cows wont be moving out for a while....get plenty of quotes as so many wrong uns out there trying to bolt people up especially with part p now gives em excuse to hike it up a bit..........

 

[SuperKat]

Hmm.

OK What is required in a full rewire? I am guessing splitting the ring mains into smaller curcuits and new consumer unit. I will get a spark to do this.

As for the shed I am going to go though the process of notifing building control etc. I intend to run the cable to the shed and wire the shed but will leave the final connection to a spark once building control have done their bit.

What would be the right cable to use? 4mm SWA?

I assume, with it being a metal shed, the shed itself will need to be earthed.

In the shed I intend to connect the SWA cable to one of these. Apart from a gland in there anything else I will need to go inbetween the cable and the said unit?

Also what are IP55 and IP65 and which will I need?

Thanks

 

[Adam_151]

There shouldn't be any need to rewire the house just to run a new circuit out to the shed, though you will need a new CU, either just for the additional circuit or for the whole house (and the existing circuits would have to be in a reasonable condition for a spark to move them across to a new CU)

Without knowing what earthing system you are on, I can't say that 4mm² would be the right to use, if its PME and you decide to export the eqipotential zone, you'd need 10mm² , though I'd personally probably make the shed TT instead

That board arrangement will be right whatever earthing system you end up with in the shed, but it doesn't give any room for expansion (is this an issue?) and its a rubbish make

 

[SuperKat]

though I'd personally probably make the shed TT instead

Forgive me, what do you mean?

Do you mean place an earth rod next to the shed and connect the shed to it?

Can I then use that as the earth for all the shed wiring??

 

[Pensdown]

How far away is the shed from the house? If it's close PME is fine, if it's not then TT is better

 

[SuperKat]

How far away is the shed from the house?

20 Metres + 2 to the CU

 

[Pensdown]

How far away is the shed from the house?

20 Metres + 2 to the CU

IMO you would be better of sticking with PME @ 20mtrs as the TT zone would be to close to the PME zone. For example, if you plugged an extension lead into the shed socket for use outside it would reach into the PME earth zone so you could end up with 2 different earth potentials. I know most outside garden tools are double insulated but I cant see the benefit in the this instance for going TT