An outdoor socket is one of those small additions that dramatically improves how you use your garden — powering a lawnmower without an extension lead trailing through a door, running festoon lights, charging outdoor tools, or supplying an outbuilding. But outdoor electrical work is one of the areas where the UK Building Regulations are unambiguous: it is notifiable work, it requires specific cable types, and the protection requirements are more stringent than indoor circuits.
This guide explains what is legally required, what it costs, and the best approach for different garden power scenarios.
Regulatory Requirements
All outdoor electrical socket circuits in England and Wales are notifiable work under Part P of the Building Regulations. This means the installation must either be:
- Carried out by an electrician registered with a government-approved competent person scheme (NICEIC, NAPIT, ELECSA, or similar), who can self-certify the work; or
- Designed and installed by a competent person and then inspected and certified by a local authority Building Control inspector — who will charge a fee of £300–£500 for this.
In practice, almost all outdoor socket work is done by registered electricians who self-certify. On completion you receive an Installation Certificate under BS 7671 (18th Edition IET Wiring Regulations).
Do not be tempted to DIY outdoor socket work without certification. Your home insurance may be invalid for any electrical fault or fire if notifiable work was not certified. When you come to sell the property, solicitors routinely request electrical certificates.
Protection Requirements: RCD is Mandatory
Every outdoor socket circuit must be protected by a 30 mA residual current device (RCD). This is a hard requirement under BS 7671 (Regulation 411.3.3). In most modern consumer units (fuse boards) fitted since around 2010, RCD protection is already provided by an RCBO or by the RCD protecting the relevant circuit. Your electrician will confirm this at the design stage.
In addition, sockets installed outdoors must be:
- IP-rated to at least IP44 (splash-proof) for a standard outdoor location. IP55 or IP65 is recommended near water features, hose connection points, or any exposed coastal location.
- Suitable for outdoor use — standard indoor sockets are not acceptable even under cover.
Cable Types and Burial Depths
The cable run from the house to the outdoor socket is the most technically critical element.
| Route | Permitted cable type | Minimum depth |
|---|---|---|
| Buried in garden (no protection) | 6242Y twin + earth in 25 mm conduit is insufficient — must use 2.5 mm² SWA (steel wire armoured) | 500 mm (earthed areas) |
| Buried in garden under concrete / drive | 2.5 mm² SWA armoured cable | 500 mm |
| Surface-run on exterior wall | 2.5 mm² singles in rigid conduit, or SWA | N/A |
| Overhead (span under 3 m) | 2.5 mm² or 4 mm² aerial bundled cable on a catenary wire | At least 3.5 m above ground |
SWA (steel wire armoured) cable is the standard for buried garden cable runs. The steel wire armour provides mechanical protection against garden forks and spades. For a single outdoor socket, 2.5 mm² 2-core + earth SWA is almost always sufficient. SWA cable costs £3.50–£6.00 per metre supplied.
The cable must be identifiable along its route — either by cable marker tape laid above it at 100 mm depth, or by routing the cable along a line that is unlikely to be disturbed (fence line, wall base). Draw a plan and keep it with the Building Regs certificate.
Cost Guide
| Scenario | Typical cost (2026, inc. VAT) |
|---|---|
| Single outdoor socket, surface-run cable from nearest indoor socket | £180–£300 |
| Single outdoor socket, buried cable run (up to 10 m) | £250–£450 |
| Twin outdoor socket, buried cable (up to 10 m) | £300–£550 |
| Dedicated garden circuit from consumer unit, up to 20 m buried run | £450–£800 |
| Outbuilding supply (sub-panel, lighting + sockets) | £800–£2,000 |
These prices include labour, materials (SWA cable, back box, outdoor socket, any conduit, fittings), and the Part P self-certification certificate.
Garden Power Options Beyond Standard Sockets
Weatherproof Extension Columns
Free-standing socket columns (e.g. for a patio or decking area) can be fed by a buried SWA cable. They provide 2–4 socket positions at a convenient height and are rated for permanent outdoor installation. Supply-only cost: £80–£200.
Outbuilding Supply
A detached garage, workshop, or home office that requires multiple circuits or significant load (240V power tools, an electric car charger) is best served by a dedicated SWA supply from the main consumer unit, with a small sub-panel (consumer unit) in the outbuilding providing separate circuits for lighting, sockets, and any specific equipment.
This is a larger project — expect £800–£2,000 for a typical garage/workshop — but correctly done it is much safer than multiple extension leads from the house and avoids the risk of nuisance tripping on a shared household circuit.
Low-Voltage Garden Lighting (12V)
Low-voltage garden lighting systems (transformer in the house, 12V cable buried to outdoor fittings) are not covered by Part P in most cases — 12 V SELV (Separated Extra Low Voltage) circuits are exempt from notification. This makes DIY installation of low-voltage path and patio lighting legal and straightforward. Cable must still be buried at least 150 mm deep (or run in conduit) to avoid damage from gardening.
Solar-Powered Outdoor Lighting
Battery-backed solar lights require no electrical connection and no regulatory compliance. Quality solar garden lights (lithium battery, 4–8 hour runtime) range from £15–£80 per unit. For lighting applications that do not need mains reliability, solar is the simplest option.
Choosing an Electrician
For Part P notifiable outdoor work, use an electrician registered with one of the government-approved competent person schemes:
- NICEIC — the largest; check registration at niceic.com.
- NAPIT — widely used by smaller contractors.
- ELECSA — common in southern England.
Ask for a quotation that specifically includes the Part P certificate and BS 7671 Installation Certificate. A reputable electrician always includes this — if a contractor does not mention certification, treat this as a red flag.
Get at least two quotes for jobs over £400. Prices vary significantly by region — London and south-east England typically run 25–40% higher than the Midlands and north of England for the same scope of work.
