Getting power to a garden room without regretting it later

What a proper supply looks like

The standard approach is a dedicated circuit from the house consumer unit, run in steel wire armoured cable, buried in a trench at a safe depth with warning tape above it, terminating in a small consumer unit inside the garden room. From there, separate circuits feed sockets and lighting.

Cable size depends on the load and the length of the run, because voltage drops over distance. That calculation is the electrician's job and it is a real reason two quotes can differ.

Typical loads by garden room use. Use | Typical demand | Worth allowing for. Office — Low: laptop, screens, small heater — Ethernet, desk height sockets; Gym — Moderate: cardio kit, fan, lighting — Dedicated socket at machine position; Bar — High: fridges and coolers running together — Separate appliance and lighting circuits; Studio with kiln or heavy tools — High and specialist — Load assessed individually before design; Room with shower — High during use — Dedicated circuit for the shower unit Load and cable sizing should be calculated for your run length by the electrician doing the work.

Part P and certification

New circuits and work in the garden are notifiable under Part P of the building regulations in England. That means the installation must be carried out and certified appropriately, either by a registered competent person or notified to building control.

Keep the certificate. It comes up when you sell, and unrecorded garden wiring makes buyers and their solicitors nervous for good reason.

Designing the circuits around real use

Standard practice puts sockets on one circuit and lighting on another, so a tripped appliance does not leave you in the dark. Beyond that, think about where equipment will genuinely live.

Sockets at desk or bench height where the work happens · One outdoor rated socket by the door for tools and garden equipment · External light on a switch inside and outside · Dedicated circuits for high draw items such as a shower or fixed cooling unit · Ethernet, and a spare draw cord in the duct for whatever comes next

Lighting that suits the room

Small buildings do badly with a single central fitting: it lights the middle of the room and leaves the working surfaces in shadow. Layered lighting works better, combining a general layer with task lighting where you actually do things.

For offices and studios, choose fittings with good colour rendering. For a bar, dimmable circuits change the atmosphere far more effectively than clever fittings.

Doing it once

Almost every retrofit request we get comes down to one of three things: not enough sockets, no network cable, or lighting in the wrong places. All three cost very little at first fix and are disruptive later because the walls are insulated and finished.

Frequently asked questions

Can I run a garden room from an extension lead?

No. A garden room needs a permanent, properly sized supply on its own circuit, installed and certified as notifiable work. Extension leads across a garden are unsafe and will not satisfy a buyer's solicitor either.

How deep does the cable to a garden room need to be buried?

It needs to be at a depth that protects it from damage from digging and cultivation, in armoured cable with warning tape above. Your electrician will set the depth for your ground and route.

Does a garden room need its own consumer unit?

In most cases yes, so that sockets and lighting sit on separate protected circuits within the building rather than everything hanging off a single supply.

Is garden room wiring notifiable under Part P?

Yes. New circuits and outdoor electrical work in England are notifiable, so the installation must be certified by a competent person or notified to building control.

How many sockets should a garden room have?

More than feels necessary, placed at the height the equipment will sit. Adding them after the insulation and plaster are in is far more disruptive than fitting spares at first fix.