power to new out building

[Helpme]

I am just about to lay a patio and would prefer to dig a trench and lay cable (in a tube if possible so I can add other services as technology changes) to an outbuilding I would like to build in the next year or two. The outbuilding will be an office and workshop, approx 20 sq m.

What cable should I use? Do I run cable in both directions for a ring, or do i just lay 1 cable? Does it have to be armoured if it is inside a tube (The sort they lay cables in at the side of the motorway). I dont want to do the electrics, only lay the correct cable so I dont have to dig up the patio again in 12 months!

A huge thanks in advance for your help

 

[davy_owen_88]

What kind of workshop? How far will it be from the house consumer unit?

You will want a separate supply from the consumer unit/meter tails supplying a consumer unit in the outbuilding - this will require a single cable feeding it and all circuits will be fed from that.

Unless you used earthed metal conduit then the cable must be armoured. It is easier to lay SWA than to run standard cable inside earthed conduit.

Could you just lay the ducting now and install a draw line to add the cables later?

 

[breezer]

lay 2 pipes, one for electric supply other for data etc

 

[Helpme]

thanks for the speedy replies. The building will be approx 50ft away from the consumer unit.

The workshop will be nothing exceptional. I would like to squeeze in a lathe if possible, but everything else will be standard power tools. All 240v.

What rating of cable should I buy and can you recommend a supplier? Also, where do i buy the ducting/pipe?

Thanks

 

[Taylortwocities]

To calc cable size you first must tell us how many amps you will be drawing. How big is a lathe? Single phase, three phase? Its a motor so will have relatively high inrush currents
Will you have heaters in your outbuilding? etc etc.

SWA available from any electrical wholesaler or on the NET (Screwfix, TLC, etc etc)

More info = more help...

TTC

 

[Helpme]

Single phase lathe. 3Kw heater. PC, TV, Music, Lights, 0.5kw outside floodlight, Kettle, electric fan.

Nothing too complicated and hugely power hungry.
Thanks again

 

[Lectrician]

Lay two 4 inch cival pipes. They are just black 4 inch thin walled ducts. Keep them straight, and minimise bends - if you use bends, use ones designed for the civil pipe, as they are intended for cables, and are swept. You can leave the end of the pipe burried, marked with a stake or something until the future.

Bung in some blue rope if you can, but this can be wapped through after fairly easily.

 

[Helpme]

Thanks to everyone.

I am struggling to source 4" conduit. I can only find 25mm, which is the biggest I can locate.

Any advice on the size of cable I should use? It would be easy to lay it now and let an electrician connect it up some point in the future.

 

[Chri5]

I'd use 10mm SWA see here http://www.tlc-direct.co.uk/Products/SW10slash2.html and I'd dig the trench 450mm deep ( in non cultivated area- such as lawn or under path), I think it's 600mm deep for areas where you might cultivate (dig).

I wouldn't bother with a duct since you do not have to, other than for replacement of cable in 30 years time

Regarding comms, data and voice I would get some plumbing waste tube 40mm, something like http://www.drainageonline.co.uk/products.php?category_id=43- Do run in a draw wire as you lay it.
Duct is required for separation of service from power cable and commonly voice and data cable are internal grade (although Cat 5 external and voice cable can be purchased.

Before I get called a barsteward for suggesting 10mm SWA my logic is that I have no idea on the power of a lath, although the cable is rated at 80A it's better to be over than under sized.

No doubt a sub main of either 40A or 60A will be more than enough

 

[Lectrician]

Dont search for conduit - search for DUCT

http://www.trademate.co.uk/products...duct&SearchMode=Product&KeyPart1=A&Keypart2=3