CONVERSION GUIDE

Garage Conversion Electrical Work: Wiring Guide for UK Homeowners

Everything you need to know about electrical work in a garage conversion — upgrading from basic garage supply to full habitable room standard, heating options, consumer unit considerations, Part P notification, and the mandatory Electrical Installation Certificate.

Start 7-day free trial

Free for 7 days · No charge until day 8 · Cancel anytime · Used by 1,000+ UK electricians

12 min readUpdated 2026-05-18Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

ShareXinW
Follow

1,000+

UK electricians

“Replaced three separate apps with Elec-Mate. Certs, quotes, and scheduling all in one place.”

Daniel Palmer — DP Electrical

Key Takeaways

  • 1A garage being converted to a habitable room must have its electrical installation upgraded to full domestic dwelling standard under BS 7671:2018+A4:2026 — the basic garage supply (lighting, one or two sockets) is not sufficient.
  • 2All electrical work in a garage conversion is notifiable under Part P of the Building Regulations 2010. An Electrical Installation Certificate (EIC) is legally required on completion.
  • 3An attached garage fed from the main house consumer unit must have its circuits reviewed and upgraded — the existing garage sub-circuit is typically not rated for the demands of a habitable room.
  • 4A detached garage being converted to living space will require a separate sub-board or consumer unit, either fed from the main house via SWA armoured cable or via a new DNO supply — specialist electrical design is required.
  • 5Electric heating is the most common heating solution for garage conversions due to the difficulty of extending the gas central heating system. Underfloor heating, infrared panels, and electric panel heaters all have different circuit requirements.
01 · Conversion Guide

Attached vs Detached Garage Conversions

The electrical approach for a garage conversion differs significantly depending on whether the garage is attached to or detached from the main house. Understanding this distinction is essential for planning the electrical installation correctly.

  • Attached garage — shares a wall with the main house. New circuits can be run directly from the main consumer unit through the shared wall. This is the simpler and more cost-effective approach. The existing garage sub-circuit (if any) will be replaced or supplemented with properly rated circuits for the habitable room use.
  • Detached garage — requires a separate supply from the main house. This is typically achieved using SWA (steel wire armour) armoured cable buried in a trench between the house and the garage, feeding a sub-board or consumer unit in the garage. The armoured cable route, trench depth, and earthing arrangement must comply with BS 7671. See the outbuilding electrical installation guide for full details on the SWA cable requirements.

In both cases, the existing garage electrical installation — typically consisting of a single lighting circuit and one or two socket-outlets on a basic sub-circuit — is wholly inadequate for habitable room use and must be replaced or significantly upgraded.

Free download

Get the BS 7671 A4:2026 Cheat Sheet — free

Every key change in the 2026 amendment on one page. AFDDs, TN-C-S protection, new schedule columns, model forms. Pinned on your van dash.

  • Every regulation change summarised
  • New model forms (EIC + MEIWC)
  • Free PDF — no subscription

We'll email it once. No spam — unsubscribe any time.

02 · Conversion Guide

Upgrading the Electrical Supply for Habitable Use

The first task when converting a garage electrically is to assess the existing supply and determine what needs to be upgraded. In most cases, this means installing entirely new circuits rather than modifying the existing ones.

  • Assess the main house consumer unit — check for spare ways, main fuse rating, and RCD protection. If the consumer unit is old or lacks RCD protection, upgrading it as part of the garage conversion project is strongly advisable and may be required to provide adequate protection for the new circuits.
  • Cable sizing for the garage feed — if the garage is to be fed from the house consumer unit, the feed cable must be sized for the total load of all circuits in the converted garage. For a room with heating, lighting, and socket-outlets, the feed cable is typically 10mm² or 16mm² twin and earth (for an attached garage) or SWA armoured cable of appropriate cross-section (for a detached garage).
  • DNO involvement — if the main house supply cannot support the additional load of the converted garage (particularly with electric heating), the Distribution Network Operator (DNO) must be consulted about a supply upgrade. DNO upgrades can take several weeks to arrange and should be factored into the project timeline.
03 · Conversion Guide

The Habitable Room Electrical Standard

A converted garage used as a living room, bedroom, home office, or playroom must meet the same electrical standard as any other room in the house under BS 7671:2018+A4:2026. This is a significant step up from a typical garage installation.

  • Socket-outlet provision — a minimum of four to six double socket-outlet positions for a living room or bedroom use. All socket-outlet circuits must have RCD protection with a rated residual operating current not exceeding 30mA, under Regulation 411.3.3 of BS 7671.
  • Lighting — a dedicated lighting circuit with switched control. LED downlighters are a popular choice for converted garages with lower ceiling heights. Confirm that the driver type is compatible with the dimmer switch if dimming is required.
  • Smoke detection — a mains-powered smoke alarm with battery backup (Grade D under BS 5839-6:2019), interlinked with the existing alarms in the house.
  • Earthing and bonding — the converted garage must have a proper earth connection via the main earthing terminal. Any metallic water or gas pipes entering the converted space must be bonded to earth under Regulation 544 of BS 7671.
04 · Conversion Guide

Heating Options for Converted Garages

Heating is one of the most important decisions in a garage conversion. Most garages are not connected to the gas central heating system, and extending the system is often costly and disruptive. Electric heating is therefore the most common solution.

  • Electric underfloor heating — the most popular option for converted garages with a concrete floor. A heating mat is installed under the floor covering and connected to a dedicated circuit with a thermostat and floor sensor. For a 15m² garage, a 2kW system on a 10A circuit is typical. The thermostat must be appropriate for the floor type — tile, laminate, and carpet all require different sensor configurations.
  • Electric panel heaters — wall-mounted electric panel heaters with programmable thermostats are a lower-cost option. A 2kW panel heater requires a 10A circuit. If multiple heaters are installed, a dedicated heating circuit or separate circuits for each heater should be used rather than connecting to the general socket ring.
  • Infrared heating panels — ceiling or wall-mounted infrared panels heat objects rather than air, making them efficient for well-insulated spaces. They can be connected via a standard 13A socket or hardwired on a dedicated circuit. For a permanent installation in a habitable room, hardwiring is preferred.
  • Extending gas central heating — technically possible but requires a Gas Safe registered engineer to extend the pipework, a new radiator installation, and a check that the boiler has sufficient capacity for the additional load. For most garage conversions, the cost and disruption of extending gas heating makes electric heating the more practical choice.

Try Elec-Mate free for 7 days

16 certificate types, 70+ calculators, RAMS, quoting, invoicing, AI agents, and 46+ training courses — from £6.99/mo.

Start free trial
Download on the App StoreGet it on Google Play
05 · Conversion Guide

Consumer Unit Considerations

The consumer unit serving the converted garage (whether it is the main house unit or a dedicated sub-board) must meet the requirements of BS 7671 for a domestic installation.

  • Non-combustible enclosure — under Regulation 421.1.201 of BS 7671, consumer units in domestic premises must have a non-combustible enclosure. Metal consumer unit enclosures are the standard solution. Older plastic-encased consumer units must be replaced if the unit is being upgraded.
  • RCD protection — all socket-outlet circuits must be protected by a 30mA RCD. For a sub-board serving a converted garage, a dual-RCD or RCBO consumer unit is appropriate. RCBOs (individual RCDs combined with circuit breakers) provide the advantage that a fault on one circuit does not trip the entire board.
  • Sub-board for detached garages — a detached garage conversion requires a consumer unit or sub-distribution board at the garage end of the SWA feed. The sub-board must have a main switch (isolator) and appropriate circuit breakers for each circuit. The earthing arrangement for the sub-board must be determined by the earthing system of the main house installation.
06 · Conversion Guide

Part P and Building Regulations for Garage Conversions

All electrical work in a garage conversion is notifiable under Part P of the Building Regulations 2010. In addition, the overall garage conversion requires building regulations approval covering structure, fire safety, insulation, and ventilation.

  • Competent person scheme — use a NICEIC, NAPIT, or ELECSA registered electrician to self-certify the electrical work under Part P. This avoids the need for a separate building control electrical inspection.
  • EIC on completion — the electrician must issue an Electrical Installation Certificate (EIC) on completion. This document must be provided to the homeowner and retained with the building regulations completion certificate. Use the Elec-Mate EIC app to complete and issue the certificate on site.
  • Consequences of non-compliance — without a valid EIC and Part P notification, the conversion cannot receive building regulations sign-off. This will affect the property's value, its insurability, and the ability to sell in the future. Retrospective regularisation is possible but involves an EICR on the existing installation and can be expensive.
07 · Conversion Guide

For Electricians: Garage Conversion Electrical Contracts

Garage conversion electrical work is reliable, profitable, and accessible for domestic electricians. A full garage conversion — supply upgrade, lighting, sockets, heating circuit, smoke detection, testing, and EIC — typically generates £1,200 to £2,800 in revenue.

Issue the EIC Same Day

Use the Elec-Mate EIC certificate app to complete and issue the EIC on site, including the full schedule of test results. Clients appreciate same-day documentation, and it protects you if questions arise later.

Win with Professional Quotes

Use the quoting app to produce a detailed, itemised quote for the conversion electrical works. Include all materials, labour, testing, EIC, and Part P notification in a single professional document.

Run your garage conversion jobs with Elec-Mate

Join 1,000+ UK electricians using Elec-Mate for EIC certificates, quoting, and job management. Complete more jobs with less paperwork. 7-day free trial.

Try it free for 7 days
Download on the App StoreGet it on Google Play

Frequently Asked Questions About Garage Conversion Electrical Work

What electricians say

Verified reviews from the UK App Store.

One App for Everything!

Elec-Mate is my go to app for business and electrical work. It's feature rich without feeling cluttered. A true all in one app for quotes, certs, calculations, RAMS, EICRs, and more. I use it every day without fail, and it makes my workflow much smoother since I'm not jumping between apps anymore. The price-to-feature ratio is excellent. Any issues I've had, the developer responds within the hour and usually fixes them the same day. 100% recommend.

Apple App Store · GBR

Fantastic app for electricians

I've used the app and the web based version for a while now and it's well worth the investment. If you're an apprentice or experienced Spark give it a go, you won't be disappointed.

Apple App Store · GBR

Absolutely amazing

I've been using Elec-Mate for a while now, and honestly, it's one of the best apps I've ever downloaded. Every aspect of it feels thoughtfully designed, from the clean and intuitive interface to the powerful features that make everything so easy to manage. It's clear that a lot of care and attention went into building this app, and it shows in every detail.

Apple App Store · GBR

Trusted by electricians across the UK

Real feedback from real sparks

“Replaced three separate apps with Elec-Mate. Certs, quotes, and scheduling all in one place.”

Daniel Palmer

Sole Trader · DP Electrical

“I've won two contracts this month because I could turn quotes around same-day with the AI cost engineer.”

Nathan Perry

Electrician · NP Electrical Services

“The study centre got me through my AM2. Mock exams and flashcards are brilliant.”

Jake Pizey

3rd Year Apprentice · Apprentice

7-Day Free Trial — Cancel Anytime, No Hassle

Complete Garage Conversion EICs on Your Phone

Join 1,000+ UK electricians using Elec-Mate for on-site EIC completion, quoting, and Part P compliance. 7-day free trial, cancel anytime.

“Replaced three separate apps with Elec-Mate. Certs, quotes, and scheduling all in one place.”

Daniel Palmer, DP Electrical

From £6.99/mo after trial — less than a coffee a week

or download the app
Download on the App StoreGet it on Google Play
7 days free, then from £6.99/moCancel in one tap — no calls, no hassleiOS, Android & WebBS 7671 compliant
16
Certificate Types
70+
Calculators
46+
Training Courses
8
AI Agents

1,000+ electricians · From £6.99/mo after trial

App Store

We use cookies to improve the app and measure what works. Cookie Policy