Before & After — Wiring a Detached Garage From Scratch
By Frankie · April 2026 · 4 min read
One of my most popular jobs is supplying power to detached garages and outbuildings. This one is a good example of what’s involved, and the difference it makes.
The Starting Point
This detached garage had nothing more than a single pendant light hanging from the ceiling. No sockets, no consumer unit, no proper electrical supply. The customer wanted to actually use the space, and for that, they needed proper power.
What I Installed
I ran a steel wire armoured (SWA) cable from the house, routing it neatly along the external wall at low level and through to the garage. SWA is the correct cable for this kind of external run. It’s tough, weather-resistant and provides its own mechanical protection.
Inside the garage, I installed a dedicated BG consumer unit with a 100A main switch and individual MCBs protecting separate circuits:
- B6, lighting circuit
- B16, socket circuit
Everything is surface-mounted in white conduit, keeping it tidy against the exposed brickwork.
The Result
A fully functional garage with proper lighting and double sockets, its own dedicated supply and individual circuit protection. Tested, certified and labelled with the installation date and next recommended inspection.
What Does a Garage Power Supply Cost?
Every job is different depending on the distance from the house, the number of circuits and the existing supply. I provide free, no-obligation estimates, just get in touch and I’ll come and have a look.
Key details:
Cable: Steel wire armoured (SWA), external surface-mounted run
Consumer unit: BG with 100A main switch, B6 and B16 MCBs
Circuits: Lighting (6A) and sockets (16A)
Containment: Surface-mounted white conduit on brickwork
Certification: Electrical Installation Certificate (EIC) to BS 7671
Frankie Sewell
NICEIC Approved Contractor • YRLA Recognised Service Provider • Bright Sparks of York
Frequently asked questions
How much does it cost to wire a detached garage?
Every job is different depending on the distance from the house, number of circuits, and site conditions. A typical single-garage installation with lighting and sockets is scoped on site. I provide free, no-obligation estimates after a site visit.
What cable is used to run power to a detached garage?
Steel wire armoured (SWA) cable is the standard for running power to a detached garage. It provides its own mechanical protection, is weather-resistant, and is suitable for external surface-mounted or underground runs. Standard domestic cable is not suitable for outdoor or underground use without additional protection.
Does a detached garage need its own consumer unit?
Yes. A detached outbuilding should have its own consumer unit (or small distribution board) with individual circuit protection. This provides local isolation and separate MCBs for each circuit, typically one for lighting and one for sockets.
Do I need a certificate for garage electrics?
Yes. A new electrical supply to a detached garage is notifiable under Part P of the Building Regulations. An Electrical Installation Certificate (EIC) must be issued on completion. I am registered to self-certify notifiable work like this, so Building Control is notified for you rather than by you.
Need Power to Your Garage or Outbuilding?
Tell me what you need and I’ll give you a clear estimate based on the actual cable route. No obligation.