Attention Sparkies! Help needed - power to outbuildings

[GreatOldOne]

Hi chaps,

I'm building a shed in the back garden to house my Lathe and other machine tools I plan on getting later on. Obviously this will all need power.

I need some advice on the best way to run the cabling to the shed.

Here's a rough, not to scale layout of the house and the sheds:



The main consumer unit is in the garage.

My initial thought is it would be easier and cheaper to take a feed from the consumer unit out of the garage wall and then straight up to the loft, with the cable in some galvanized conduit. Then run the cable through the loft to the opposite wall and then down toward the sheds in more conduit, with the main feed ending up in the workshop and a separate small consumer unit there.

Here it would feed 4-5 double 13amp sockets and some fluorescent lighting, and some form of light in the shed down the side of the house.

What I need to know is would this be OK by the electrical regs?

I know this sort of thing is notifiable to the powers that be, so it would have to be signed off by a qualified professional - but how much of it can I do my self, and what needs to be left to the Sparkie?

I've tried researching this myself, but get lost with earthing methods, cable cross section, separate earths, Part P and voltage drops.

Other things - the Lathe is 1000w, 13amp. Any other machine tools would be of similar rating, but unlikely that they would be run at the same time. An outside socket on the wall of the workshop would be nice for the lawn mower.

Thanks In Advance,

Jason

[nutter]

If you not sure what earthing methods, cable cross section, separate earths, Part P and voltage drops. Then for what you are asking for I would suggest you find a suitable sparkie.

Part-P is a legal signoff on works that is done by a sparkie at the end of an installation. It was brought in to try and prevent non-component, poor DIYer doing dangerous electrical changes to thier home, making it a fire hazard and dangerous. (Most house fires are a result of poor electrical wiring or plugs)
All electrical work in a bathroom, kitchen or outside of your house will need a Part-P certificate. Because of the risk of a person coming in contact with water and electricity at the same time.

As you want to add some serious power in your shed, i would advise getting a sparkie invovled
Even though you say you dont want to use all 5 double extensions at the same time the behind scenes wiring must be able to support that load. (in case you forget to turn things off) Otherwise a fire is a possibilty, in a shed this is not good news.

Be aware the main consumer unit must be RCD protected (resettable fuses). If your consumer unit is not already RCD based, a sparkie will insist on it being RCD. You may need to upgrade this as well with live electricity around this is definitly one for the sparkie.

As for another consumer unit in the shed, this is a good idea. for lighting this should be on a 5Amp cirucit, so a seperate fuse here for the extensions and lighting is a good call.
The external socket on the shed for the lawnmower, will need to be RCD, this can be done on you shed consumer unit. (RCD for internal sockets,RCD for ligthing, RCD for external socket)

To keep the costs down, you can might be able to find yourself a sparkie, who will oversee your work.
You run the cable through your loft, secure it etc, but not connect it either end.
You screw the consumer unit to the inside of your shed.
You add extensions where you want them.
You run the wires, between the extensions.

Then you get the sparkie to check you work, make the Live connections to everything.
Check it is safe to use, then issue you with a Part-P certifcate.

You will need a PART-P certificate for the installation when you want to sell your house.

I have done things like this on my own home, including a complete re-wire of the kitchen, I did all the work got it inspected and signed of by a sparkie, who gave me a PART-P for it.

I hope that helps.
Steve

[chrislandy]

Hi GOO,
I've just had a quote for running a 60A feed to my workshop which is around £300, burried armoured cable to a new consumer unit (although the power points are not included in that)

Chris