Garage - cable rating

[scottie]

I want to run power from my shed to a garage.

The shed is some 25 meters from the house and is connected via 2.5mm armoured cable connected to 2.5mm PVC cable (via internal junction box) which runs to house CU on a 16A MCB on the RCD side of the CU. The shed has a garage/shed CU with RCD, 16A and 6A MCBs. The garage is a further 20 meters from the shed where I need to install 2/3 double sockets (on 2.5mm cable (approx ring length 30 meters)) to run electric door motors, a small freezer and occasional power washer. What’s the best way to achieve this, if at all:

1. add power to the garage by running a 2.5mm cable from the shed CU to a similar CU in the garage
2. run a new supply from the house to new CU in garage – what size cable 2.5mm or 4mm or 6mm…
3. get a new grid supply installed in the garage by electricity company
4. move garage closer to house

 

[electronicsuk]

With the loads you have described I would consider running a new cable from the house CU, otherwise you have a 45+ metre run on 2.5mmsq which will severely limit the maximum load in the garage.

 

[scottie]

just remeasured - total run to garage is 65 meters with a further 30 meters (on a ring) of 2.5mm cable required internally so definately running separate cable from house CU and considering 6mm armoured cable - will this cover me and what size MCB on house CU should i use.

 

[Steve]

Thats gonna cost you

Why are you using a ring main? You dont need to, and a radial is probably better suited.

With 6mm SWA at 60 metres, you need a 16 amp MCB at the house due to voltage drop.

With 10mm SWA you could fit a 32 amp MCB.

http://www.tlc-direct.co.uk/Products/SW10slash3.html for 10mm SWA. You can buy by the metre, but I suggest you purchase 100 metres and flog the rest on ebay or to a local spark. You always need more than you think (seriously, dont underestimate)

You could always enquire with your local network operator as to the cost of a new supply to the shed / garage.

Also consider split concentric cable. This is cheaper and more compact than SWA, as it has a central live core and the neutral and earths wrapped around it. TLC dont sell this unfortunately.

 

[plugwash]

TLC are not a particularlly cheap place to buy SWA.

http://www.electricalshop.net/acatalog/3_Core_Steel_Wire_Armoured__SWA__Cable__6943X_.html has it a bit cheaper.

also try ebay, there doesn't seem to be anything appropriate listed at the moment but when it does appear on there the price is often pretty good.