Outdoor Socket - Best Practice?

[The_Scotty]

Which is the best way to power an outdoor socket from the following scenario?

Nearest power source is a CU in a garage (which is fed by 16mm SWA from the house).

In the gararge CU is
C16 MCB marked Outside Lights (3 outside lights fed by 10mm SWA)
C16 MCB marked garage socket (one doublesocket on a radial beside the CU)
B6 MCB marked garage light (two fluro lights)
There is another C16 MCB with no markings and I've yet to ascertain what it does although it is in the ON position (it may or may not be spare)

Where the new outdoor socket would be is approx 35m (cable run) from the CU in the garage.

The outside lights are fed by 10mm SWA which joins above ground in a weatherproof box to feed the first light before travelling underground to the second and then the third light.

The new socket would be approx 3m from the final light.

The new socket is to be used for lighting a tree (Christmas style) and occasionally for a strimmer for a small patch of grass.

Cheers

 

[Keith1978]

I'd run it directly off the socket in the garage in 2.5mm twin and earth or preferably from the 16A MCB that is spare in your Garage CCU. I'm assuming that it's going to be fixed to the outside of the garage wall?

 

[The_Scotty]

I'd run it directly off the socket in the garage in 2.5mm twin and earth or preferably from the 16A MCB that is spare in your Garage CCU. I'm assuming that it's going to be fixed to the outside of the garage wall?

No Keith its 35m away from the Garage. Seriously

 

[plugwash]

how long is the run from the main house CU to the garage CU?
what breaker is the garage supply on in the house?

We need theese figures to work out the voltage drop to the garage and hence how much voltage drop is left for the new circuit.

It would also be usefull to ktnow more details on the outside lights (power, type, cable run lengh) to see if it is ok to add to that circuit or if a new circuit from the garage is needed.

 

[The_Scotty]

Thanks Plugwash, I will try and find out but TBH I think I will call the electrician.

A customer asked me 'how much would it be roughly to put a socket there' whilst we were doing some other work at her house.

I had a feeling whatever it was it would not be worthwhile economically given the potential cable run involved so I thought I'd get an idea of how best to do it.

 

[securespark]

So what trade are you in, then?

 

[The_Scotty]

Just read back my last post.

It doesn't read as it should.

I had no intention of doing the work.

I don't like calling 'our' electrician, or any other tradesman, unless I'm giving them a fairly definite lead for some work and not just a question a customer has asked in conversation.

 

[Keith1978]

I'd run it directly off the socket in the garage in 2.5mm twin and earth or preferably from the 16A MCB that is spare in your Garage CCU. I'm assuming that it's going to be fixed to the outside of the garage wall?

No Keith its 35m away from the Garage. Seriously

Right! Was tired last night when typing that, sorry.

Off the top of my head i'd probably run a bit of 4mm armoured down to it, my main concern would be what these outside lights are drawing.

 

[The_Scotty]

The first light is a 450W bulb (Newlec brand I think)

The other two I'm not sure but they are not as big as the first one.

 

[ban-all-sheds]

My main (? - significant, anyway) concern would be how long the cable to the garage is. 16mm² could be because it happened to be spare, or it could be an expectation of a heavy load, or it could be that the garage is a long way off. There's not much indication that 16mm² is needed for load reasons, so I wonder how long it is, and therefore how appropriate Type C breakers are....