How to run power to a garden shed

Inspired by a UK electrician’s practical guide. This walk-through draws on the video "The Easy Way To Install Power To Your Shed" from the Domestic Electricians Life UK channel. It shows a real installation rather than an idealised one, covers both overhead and underground cable options, and is honest about what the regulations require. Recommended viewing before you decide on your approach.

1. Understand the regulations first

Running a new electrical circuit to a garden building is notifiable work under Part P of the Building Regulations in England and Wales. This means it either needs to be carried out by a registered electrician who can self-certify the work, or you need to notify your local authority and have the work inspected.

That said, this guide explains how the job is done so you understand what is involved. Many homeowners prefer to have a qualified electrician do the consumer unit connection while they handle the cable run and shed wiring themselves. Discuss that approach with your electrician first - it is a sensible compromise that cuts costs without cutting corners.

2. Plan your cable route

You have two main options for getting cable from house to shed: underground or overhead. Underground is neater, more permanent, and safer. Overhead on a catenary wire is faster and avoids digging, but it needs enough clearance height and looks less tidy.

For underground, the cable needs to be either armoured SWA (steel wire armoured) cable buried at 500mm minimum depth under garden, or standard twin-and-earth run inside rigid conduit at the same depth. Mark the route and make sure you know where any other buried services run first - a cable locator is worth hiring for the morning.

3. Dig the trench

Dig to at least 500mm depth (600mm if the route goes under a driveway or area that vehicles might cross). The trench should be wide enough to lay the cable flat without coiling - even ground cable does not like being kinked.

Lay a strip of yellow plastic warning tape about 150mm above the cable once it is in. This is the standard marker that alerts any future digger that there is a cable below. When you backfill, compact the soil in layers rather than throwing it all back at once.

4. Run the cable and enter the shed

Use an SWA cable of appropriate size for the circuit you are running. For a typical shed with lighting and a couple of sockets, 2.5mm² twin-and-earth SWA (with the armour used as the earth) is usually adequate. Check the voltage drop calculation if the run is longer than about 20 metres.

Enter the shed through a metal cable gland that clamps the armour correctly. Inside, terminate into a small consumer unit or fused connection unit mounted on the shed wall. From there, standard wiring applies - lighting circuit, ring circuit, or whatever configuration you need.

5. Install sockets and lights in the shed

Use exterior-rated fittings for any socket or light fitting inside an unheated shed. IP44 rated at minimum for damp environments. A double socket, a switched fused spur, and a ceiling light point covers most sheds perfectly well.

Fit an RCD to the shed consumer unit as the first protective device. This is essential for safety in an outbuilding - if the armour of the cable is damaged externally, or if there is a fault inside, the RCD disconnects power before the situation becomes dangerous.

6. Connect at the house consumer unit

This is the part that requires a registered electrician. Connecting a new circuit at the consumer unit involves working in the main distribution board while other circuits are live - only qualified persons should do this. The electrician will connect, test the full circuit, and issue an Electrical Installation Certificate which you should keep with your property paperwork.

Do not skip the certification. It matters when you sell the house and it matters to your insurance.

When to call a handyman

The consumer unit connection is a job for a registered electrician, full stop. Richard works with qualified electricians in the Sandwich area and can co-ordinate the full job: cable trench, shed wiring, and the consumer unit connection - one visit, done properly, with the right paperwork at the end.