Wiring Up My Shed, well starting to think about it.

[dave1w]

I’m just about finished with my shed / man cave, and will at some point soon be needing it all wired up.

My plan is to put in the circuits, mount the socket boxes / lights and consumer u it’s, run the cables myself, then have the local electrician in the village connect it all up.

From the house to the shed 4 mm SWA, possibly 4 core so later I can extend a separate outside lighting circuit out there - to be buried for approx 20metres to the shed, go into a junction bow on outside of shed.

Internal, light circuit, done in 1.5mm twin and earth, and a ring main done in 2.5mm (feeding 5 double sockets, with maybe max 3kw at one time.)

Have garage type consumer unit in the shed. Making sure it has RCD - should this be at the House end?

I’ll be discussing with the electrician anyway, but does this sound about right?

What are the pro’s and cons of SWA buried against cable in a long flexible conduit?

Dave

 

[Taylortwocities]

I’ll be discussing with the electrician anyway

Quite honestly. Have that discussion. He/she will have to certify it all as his own design, installation and test. There are too many variables and what ifs to cover all of the bases on an internet forum.

 

[winston1]

For a start the lighting circuit does not need to be 1.5mm, 1.0mm is quite adequate, cheaper, and saves the worlds valuable resources of copper.

You only need an RCD if the feed is not already RCD protected in the house. So where does the feed come from?

You don't need a CU in the shed. Lights can come off the ring via a switched FCU fused at 5amps which is also used as the light switch. An extended outside lighting circuit can be done the same way so no need for 4 core SWA either.

SWA is preferable to flexible conduit. it is much more durable.

 

[ban-all-sheds]

My plan is to put in the circuits, mount the socket boxes / lights and consumer u it’s, run the cables myself, then have the local electrician in the village connect it all up.

Is that also his plan?

Why are you having someone else connect it all up?

What are you planning to do about Building Regulations notification/compliance?

From the house to the shed 4 mm SWA, possibly 4 core so later I can extend a separate outside lighting circuit out there

Would that be 2 x L&N, or 2 x L & 1 X N?

to be buried for approx 20metres to the shed, go into a junction bow on outside of shed.

4mm² is good for just over 30A at that distance - given how insignificant the cost of larger cable would be, consider putting a larger one in.

Internal, light circuit, done in 1.5mm twin and earth

Why 1.5mm² rather than 1.0?

, and a ring main done in 2.5mm (feeding 5 double sockets, with maybe max 3kw at one time.)

Why a ring rather than a radial?

Have garage type consumer unit in the shed. Making sure it has RCD - should this be at the House end?

Will the cable from house to shed require RCD protection?

Would you prefer to go back to the house if the RCD tripped while you were in the shed?

I’ll be discussing with the electrician anyway

You probably should, sooner rather than later, depending on what responsibilities you are expecting him to assume.

but does this sound about right?

There are questions....

What are the pro’s and cons of SWA buried against cable in a long flexible conduit?

The latter is less likely to be safe enough to comply. Best idea is buried ducting with SWA inside. 2 ducts, one for power, one for data. Draw ropes left in to allow more cables later if needed.


Given all your questions etc, who do you anticipate signing this:

I being the person responsible for the design of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the design hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2015 except for the departures, if any, detailed as follows:​