Wiring a Log Cabin

[Steve 34]

Hi

I need to put in a supply for a log cabin, I have power to a shed nearby (10m away from the cabin) via 2.5mm inside plastic conduit. Can I take a supply from that or do I need to upgrade the whole supply to 4mm. The shed supply is taken directly from the consumer unit protected via a 15A MCB. The load on both the shed and cabin will be quite low, occasional power tools and lighting there are no appliances left on in either. I have a unit with a RCCB and 2 MCB's I can use, should I put that in the shed (currently only protected by a old consumer unit wire fuses and no RCD) or in the cabin.

Steve M

 

[davy_owen_88]

How far from the house consumer unit is the shed?
What cable is used to supply the shed?
Is the shed circuit protected by an RCD at the house end?

Firstly, as you are in Wales this work will be notifiable to your LABC, and you must inform them before you begin work (or you must aquire the services of a qualified, competent and registered electrician to carry out the work for you).

As you say the load will be low, you could take a feed from the shed but depending on the circuit length you might need to upgrade the supply cable to cope with the additional load and increased voltage drop.

Until you answer the initial questions though, there isn't really much else we can do to help.

Davy

 

[ban-all-sheds]

And what type of supply is it?

And are there any extraneous-conductive-parts in either the garage or the log cabin?

 

[Steve 34]

Hi

Thanks for the replies

Distance - about 20-25m
Cable -2.5mm t & e
Protection via rcd
Power supply - not sure of the type, 1 cable entering main fuse 2 tails exiting with a separate earth via earth rod
No extraneous-conductive-parts in either shed or cabin

 

[davy_owen_88]

You will definately need to replace the supply cable to the shed because twin and earth is not suitable for burial unless protected by earthed steel conduit. Plastic conduit will not provide any mechanical protection whatsoever and whoever installed it shouldn't be touching electrical work.

As you are replacing the cable I would definately recommend a minimum of 4mm² SWA but 6mm² would be better to provide some spare capacity for future upgrades (garden lights, pond pump etc).

As you have a TT earthing arrangement, you can use 2-core SWA with a dedicated earth rod local to the shed.

Do you want separate lighting circuits or will lighting be supplied by lamps connected to the sockets? I would also recommend you get shot of the rewireable fuse box and replace it with the newer MCB/RCD's.

I assume that because you have a TT supply that the shed is connected to the 30mA RCD and not the 100mA time-delayed rcd? If the supply cable to the shed is not buried in a wall at a depth of less than 50mm I would suggest that you switch the circuit over to the S-type RCD and then use a 30mA RCD in the shed to protect all circuits.

SWA requires suitable glands and an adaptable box to terminate the cable to. This should be situated next to your house consumer unit and a similar box before the consumer unit in the shed.

 

[ban-all-sheds]

11A then if you stick with 2.5mm².....