what size cable

mickjohnlong

i am looking to run power out to a shed but dont know what size cable to run planning on putting a consumer unit in the shed. i will be putting in a few sockets and a light any help would be great

paddy147

You could probably safely use 3 core 4 square or 6 square SWA for your shed.

I used 3 core 10 square SWA for my garage,but thats for future proofing and to allow for future use of any diy equipment and machinery down there.




The SWA runs underground through ducting,down through the back garden to the garage.

The SWA goes into an IP Rated Fuseboard inside the garage (you must use an IP Rated board for a shed/garage) and I have 2 lights,4 double sockets,alarm system and leccy roller garage door on the garage fuseboard.

mickjohnlong

thanks for the reply would i need to go with the 10sq i would be putting a lot of stuff in it or much of a load on it also if i was using the armoured cable could it be clipped to the wall as i have no ducting to the shed

2011

mickjohnlong wrote: »

thanks for the reply would i need to go with the 10sq i would be putting a lot of stuff in it or much of a load on it also if i was using the armoured cable could it be clipped to the wall as i have no ducting to the shed

To be able to size a cable it is essential to state length of run.
If it just a light and a few sockets for general use and the run is short a 10 sq. as suggested should be fine.

Yes you cloud clip to the wall, cleats with screws would be better. Use plenty of fixings or it will sag. A using chalk line will make it look better too (straight line).

mickjohnlong

its just for general use the run is roughly 50m

2011

mickjohnlong wrote: »

its just for general use the run is roughly 50m

That is a long run!
How big is the shed? Once the supply is in the shed, how far is the run to the furthest point?

What sort/size of loads are you talking about?

M cebee

yes 50mt is a long run

10sq is not the correct size for every job

mickjohnlong

its just a standard shed 12x12 i think mainly a light and sockets just to have if needed cant imagine any great load going on it

2011

mickjohnlong wrote: »

its just a standard shed 12x12 i think mainly a light and sockets just to have if needed cant imagine any great load going on it

What you should do is:
1) Work out your maximum possible load.
2) I would add 25% to this for future expansion, but you don't have to. Treat this as your "design current"
3) Select the next fuse size above this.
4) Select the smallest sized cable that can safely carry this current continuously.
5) Ensure that the volt drop using this cable size is within permissible values for this length of run while carrying the design current calculated earlier. If the volt drop is excessive go up a cable size until the hold drop issue is resolved.

Also bear in mind:
* It is best to have no joins on the cable whatsoever.
* Ensure that the armor on the SWA is suitably bonded by using proper SWA glands. I personally prefer the CW type.

M cebee

yes that's about it i reckon

the volt drop includes tails+sub-main and final circuit

and a spark can get an idea of the end loop impedance from the impedance at main DB and impedance of sub-main and final cct
http://www.tlc-direct.co.uk/Book/5.3.6.htm

2011

M cebee wrote: »

the volt drop includes tails+sub-main and final circuit

Well said

Bruthal

It musy be a nasa control centre going in this shed.