Home working has made outbuilding supplies one of our more frequent requests. Done properly, it is a dedicated circuit from the house, in armoured cable, terminating in a small distribution board in the building — with its own protection and its own certificate.
What a correct supply looks like
The specification follows the load and the distance, and both matter more than people expect over a long run.
- Correctly sized steel wire armoured cable for the load and length
- Buried at suitable depth with marker tape, or otherwise protected
- Glanded terminations at both ends
- A small consumer unit in the outbuilding with its own protection
- Earthing arrangement assessed for the specific installation
Sizing for what you will actually run
A laptop and a couple of monitors is a small load. A heater, a kettle and a workshop tool is not. Tell us what the building will be used for in winter, because heating is what usually decides the cable size.
Certification
A new supply to an outbuilding is a new circuit, so it is notifiable and comes with an Electrical Installation Certificate covering the supply and the distribution within the building.
Common questions
- Can I run it from an outdoor socket?
- No. An outbuilding needs its own correctly designed supply.
- Do you dig the trench?
- We can, or your groundworker can to our specification — often cheaper if they are already on site.
- Can lighting and sockets both be included?
- Yes, via the small board in the building.
- How long does it take?
- Typically one to two days once the trench is available.
Tell us the distance from the house and what you will run in there, and we can size the supply.
Related guides
- Outdoor Sockets and Garden Lighting That TripGarden electrics live outdoors, and outdoors is where every weakness in an installation eventually shows.
- Planning Outdoor and Garden LightingGood exterior lighting is mostly about restraint, direction and IP ratings.
- Electrics for Working From HomeMost home offices were bedrooms, and bedrooms were wired for a lamp and an alarm clock.