External Garage needs leccy.

[Laurence Harvey]

External Garage needs leccy.

My son would like to run mains electricity to his brick-built garage at the rear of his house;...a double-socket and lighting would suffice. The garage sits parallel to the back-wall of his house and the gap between the two is about 9 metres. His house is 20 years old and has an RCD consumer unit that is sited in his hallway at the front of his house.

Whilst being very mindful of rules, regulations and legality he’d like to do as much of the preparatory (non technical) work as possible himself. i.e. digging out a trench for underground cable etc.

With the above in mind a few questions please:

Is it feasible/allowable to run a ‘spur’ to the garage from a ring main socket that’s sits in his kitchen on the rear wall of his house?

If ‘yes’,...what type/size cable would be required and what regulations govern the installation of said cable? How deep would the trench need to be? Are there any other legal requirements?

With regard to the technical side of things at what point would a ‘qualified’ electrician need to take over?... does the work need certification?

At this early stage we’re just looking for initial guidance, advice and any relevant comments.

As ever, all replies gratefully received.

 

[winston1]

You can run a spur from a socket via a FCU but better to run from a spare way on the CU but that then becomes a new circuit and is notifiable.

Cable should be SWA and if running from a spur off a socket can be 2.5mm. If running from the CU the size depends on the size of the breaker feeding it.

Trench is generally about 50cm deep.

No need for a CU in the garage as some recommend. The socket can be wired direct and the light via a switched FCU as a light switch fused at 5 amp.

 

[Laurence Harvey]

You can run a spur from a socket via a FCU but better to run from a spare way on the CU but that then becomes a new circuit and is notifiable.

Cable should be SWA and if running from a spur off a socket can be 2.5mm. If running from the CU the size depends on the size of the breaker feeding it.

Trench is generally about 50cm deep.

No need for a CU in the garage as some recommend. The socket can be wired direct and the light via a switched FCU as a light switch fused at 5 amp.

Many thanks for the reply winston.

With regard to the FCU:...where would it be sited?...inside the house next to the socket?... or in the garage itself?

 

[winston1]

I would site it in the house next to the socket.

 

[DetlefSchmitz]

The main problem with W's reply is that he hasn't told you how to terminate SWA into a plastic accessory. This is one reason why some people would fit a small CU, in order to have something to fit the gland to and to organise things.

 

[Mottie]

I know I’m going to be slated here but I have a 2.5mm cable coming from it’s own circuit breaker in my fuse box, going through a piece of garden hose pipe buried about a foot under my concreted drive. It’s been like that since we moved here in 1990 and had probably been fitted when the house was built in the sixties. About three years ago, my mate was replacing my concrete fence posts when his kango hit the cable and it started fizzing and sparking! It was the old type of stranded 2.5mm cable. We switched it off and we managed to pull a new piece of cable right through to the garage. In my garage I have two double sockets and the lights are fed via a 5 amp fused spur. From the first socket in the garage, a 2.5mm cable extends to my shed through some crinkly plastic type of conduit to another double socket powering a small freezer and a tumble drier. Again, the shed light is fed via a spur box with a 5 amp fuse in it. It all works and it has been for years. Let the slating begin!

 

[Laurence Harvey]

The main problem with W's reply is that he hasn't told you how to terminate SWA into a plastic accessory. This is one reason why some people would fit a small CU, in order to have something to fit the gland to and to organise things.

Thanks for the reply.

If the electrician fitted a garage consumer unit at the end of the ‘spur’ would that make it a ‘notifiable’ job which in turn would mean added administrative expense?

 

[RF Lighting]

It costs an electrician about a quid to notify a notifable job, and really is not a consideration when deciding what is the best design for your installation.

 

[winston1]

Thanks for the reply.

If the electrician fitted a garage consumer unit at the end of the ‘spur’ would that make it a ‘notifiable’ job which in turn would mean added administrative expense?

It costs an electrician about a quid to notify a notifable job, and really is not a consideration when deciding what is the best design for your installation.

It would be completely unnecessary and will cost a lot more than a quid. Maybe an hour or twos work plus the cost of the CU.

 

[RF Lighting]

It would be completely unnecessary and will cost a lot more than a quid. Maybe an hour or twos work plus the cost of the CU.

It is a better design to not have a single RCD protecting both the sockets and the light.

Why would a CU take any longer than an FCU? It is the same amount of wires and connections, but with much more room to work in.

 

[winston1]

It is a better design to not have a single RCD protecting both the sockets and the light.

But he is running as a spur off his house ring which is RCD protected. i.e. a single RCD.

 

[RF Lighting]

But he is running as a spur off his house ring which is RCD protected. i.e. a single RCD.

And that is a poor design. There are better ways to do this installation.

 

[winston1]

And that is a poor design. There are better ways to do this installation.

I agree and I said so in post 2.

 

[RF Lighting]

I agree and I said so in post 2.

So how would you divide the RCD protection without installing a consumer unit in the garage?