Electrical Question

Running power cables to garden shed

Hi, I want to run a permanent power cable, attached high up on a stone wall, to a garden shed about 20m from my external (ie outside wall) power socket. It would power a low energy light (11w?) and occasionally either a small power tool or a 2kw heater in winter months. Given the power load and distance would external-quality 2.5mm power cable be man enough? Should it be run through a protective conduit to add protection from UV / weather conditions? Thoughts/advice most welcome, rgds Paul

4 Answers

Best Answer

personally I would use a 10mm armoured cable as people tend to change what they use on the circuit and pull more load. this would have to be fed from your fuseboard and run out to the shed where a small extension board would be fitted to provide a lighting and power supply

Answered 10th Aug 2013

D&C Electrical

Member since 13 Jan 2012

Firstly you need to be aware that this work is Part P building regulation notifiable and you therefore must register your intent to carry out the work and get the part P consent from your local building control office. The fees vary but typically are around £200 - £300 depending on the local authority your in. - see link below


No conduit or ducting is necessary if you use a Steel Wire Armoured XLPE cable. and ideally you would be better off using a 4mm cable and fitting a small two way fuseboard at the shed end that feeds two circuits one for lighting and one for power. You could use a 2.5m, but if loaded up to the maximum you will get some volt drop, plus a 4mm cable is not much more expensive and allows you the option of using power in future if needed.

All work you undertake must be fully compliant to BS7671:2008 and once completed the building inspector will check and test what you have done and if it passes they will issue the relevant part P certificate etc.

You may find its actually cheaper to hire a Part P registered electrician? Alternatively you could take a risk and break the law and not notify the work (not recommended as its a £5000 fine!).

Answered 10th Aug 2013

Electrical Safety Services

Member since 17 Oct 2011

Hi Paul,
Just James here from JC Electrical Solutions. In my proffesional opinion i would consider using either a 2.5 3 core armoured or braded cable and install it as a 20amp radial from your exsisting consumer unit making sure that your exsisting DB is up to 17th Edition Standard (ie dual rcd and all earthing is adequate). This would rule out the need for containment if it is out of reach.
I hope this helps Paul
Regards James
JC Electrical Solutions

Answered 9th Aug 2013

JC Electrical Solutions

Member since 12 Mar 2013

2.5 would be suitable for the loading you describe and at 20mtrs voltage drop is not an issue you could run in conduit , my preference is for armoured. RCD should be incorporated into the design. Main issue here is this is an installation in special location so is required to be either pre notified to LABC so works can be inspected as required or carried out by/under the supervision of a registered electrician who can sign the job off for you.

Answered 10th Aug 2013

kevin cassidy building contractors

Member since 16 Dec 2010

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