Getting the electrics right in your garden room is essential for safety and usability. Here's what you need to know about power supply, consumer units, and what to specify.
Garden Room Electrics: A Complete Guide
Electrics are one of the most important — and most commonly underspecified — aspects of a garden room. Getting them right from the start will save you significant cost and disruption later.
The Power Supply
The most common way to supply power to a garden room is via an armoured cable running underground from your house's consumer unit (fuse box). This is known as a sub-main.
Armoured Cable Options
- 2.5mm² SWA: Suitable for basic use (lighting, laptop, phone charging)
- 6mm² SWA: Suitable for most home offices and studios
- 10mm² SWA: Required for high-demand uses (electric heating, hot tub, EV charger)
The cable must be buried at a minimum depth of 500mm (or 450mm if covered with mechanical protection). It should be routed to avoid future excavation areas where possible.
Cost
Supply and installation of an armoured cable typically costs £500–£2,500 depending on distance, ground conditions, and cable size.
The Garden Room Consumer Unit
Your garden room should have its own consumer unit (fuse box), which provides:
- Protection for all circuits in the garden room
- RCD (Residual Current Device) protection — essential for safety
- The ability to isolate the garden room supply independently
A basic consumer unit with 2–4 circuits typically costs £300–£600 installed.
Circuit Planning
Think carefully about what circuits you'll need:
| Circuit | Typical Requirement |
|---|---|
| Lighting | 1 circuit for most rooms |
| Sockets | 1–2 circuits depending on load |
| Heating | Dedicated circuit if electric heating |
| Data/AV | Not a separate circuit, but plan cable routes |
| Air conditioning | Dedicated circuit |
| Outdoor sockets | Separate weatherproof circuit |
Sockets and Lighting
Sockets
For a home office, specify more sockets than you think you need. A typical 4m × 3m office should have at minimum:
- 4 double sockets around the walls
- 1–2 floor sockets if you have a central desk
- USB charging sockets at the desk position
Lighting
- Recessed LED downlights are the most popular choice — clean, energy efficient, and good light output
- Pendant lighting adds character but requires higher ceilings
- Consider task lighting at the desk position in addition to general lighting
- External lighting (PIR sensor light at the door) is a practical addition
Data and Connectivity
Don't rely solely on WiFi. Specify:
- Cat6 ethernet cable run from your router to the garden room (or via a powerline adapter)
- Data sockets at desk positions
- Consider a WiFi access point in the garden room for reliable wireless coverage
Part P Compliance
All electrical work in a garden room must comply with Part P of the Building Regulations (Electrical Safety in Dwellings). This means:
- Work must be carried out by a Part P registered electrician (or notified to your local council)
- You should receive an Electrical Installation Certificate on completion
- This certificate is important for insurance and when selling your property
Questions to Ask Your Garden Room Company
- Is electrical installation included in the price, or is it extra?
- What size consumer unit and how many circuits are included?
- How many sockets and lights are included as standard?
- Will you provide an Electrical Installation Certificate?
- Who carries out the electrical work — your own electricians or a subcontractor?
Always use a qualified, Part P registered electrician for garden room electrical installations.