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Garden room and garden office electrics.
A garden office needs power, light, heat and a fast connection, all running reliably at the bottom of the garden. Here is what that involves.
← All garden and exterior lighting
What a garden room usually needs
- A supply cable from the house, usually armoured, sized for what you will run out there, buried or in duct.
- Its own small consumer unit in the building, with RCD protection, so you can isolate the room on its own.
- Earthing done properly. On many homes the supply is PME, and taking that earth out to an outbuilding is not always right. Sometimes the building needs its own earth rod. We check and decide this on survey.
- Sockets, lighting and switching, including outside lights on the building and the path to it.
- Heating or air conditioning, which drives the cable size more than anything else.
- Data: a data cable or fibre in its own duct in the same trench, so the office does not rely on a Wi-Fi extender. See poor Wi-Fi signal.
Certification
A new circuit to an outbuilding is notifiable under Part P in England. We test it, issue the Electrical Installation Certificate and notify it, which you will need if you sell the house.
Plan it before the room arrives
If the base is not down yet, lay the duct now. Garden room suppliers often offer to “connect the power”; check who is signing off the work. See why to hire your own electrician.
Photographs: new-build houses in Radlett and an outbuilding in Hertford.
Questions we’re asked
What size cable does a garden office need?
It depends on the load and the distance. Lights, sockets and a laptop need far less than electric heating, air conditioning or a hot tub on the same supply. We calculate it on survey.
Do I need a separate fuse board in the garden room?
Usually, yes. A small consumer unit in the building lets you protect and isolate its circuits locally.
Can you run internet to the garden office?
Yes. A data cable or fibre in its own duct, laid in the same trench as the power, gives a reliable wired connection.
Written by SEGplc. Last updated 19 October 2026.
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