New Wiring for Extensions in Chelsea

Every type of residential extension has its own distinct electrical requirements — and getting the specification right from the outset saves time, money, and disruption during the build. Here is exactly what our NAPIT registered electricians cover for each extension type across Chelsea and South West London:

Single Storey Extensions

Single storey extensions are the most common residential extension project across Chelsea and West London — and the most common type of new wiring installation we carry out. Whether you are adding a kitchen extension, a living room, a utility room, or an open plan kitchen-diner, we design and install all new circuits to BS7671 18th Edition standards — including lighting circuits, socket circuits, and dedicated circuits for fixed appliances such as cookers, dishwashers, and washing machines. Every installation is planned around your builder's programme and certified under Part P on completion.

Double Storey Extensions

Double storey extensions require a more comprehensive electrical design — with separate lighting and socket circuits required on each floor, staircase lighting, and often additional circuits for en-suite bathrooms, home offices, or bedroom entertainment systems. Our electricians work closely with your builder to ensure first fix cabling is completed at the right stage of the build, with second fix fitted and certified once plastering and decoration is complete.

Garage Conversions

Converting a garage into a habitable room — whether a home office, a gym, a playroom, or an additional bedroom — requires a full new wiring installation to bring the space up to residential electrical standards. This typically includes new lighting circuits, socket circuits, a dedicated heating circuit, and in many cases a new consumer unit circuit to supply the converted space. We also assess your existing consumer unit capacity as part of every garage conversion survey — ensuring your installation can safely support the additional load before work begins.

Loft Conversions

Loft conversions present specific electrical challenges — particularly around cable routing, insulation requirements, and the positioning of smoke detectors and emergency lighting. Our NAPIT registered electricians are experienced in all types of loft conversion wiring across Chelsea and South West London — from simple Velux conversions to full dormer and hip-to-gable projects. We design the electrical layout around your architect's drawings, coordinate with your builder throughout, and certify all work under Part P on completion.

Garden Rooms & Outbuildings

Garden rooms, home offices, studios, and outbuildings require a dedicated supply cable run from your main property — typically buried underground to current wiring standards. We design and install the complete electrical supply for your garden room including the underground supply cable, a dedicated consumer unit within the outbuilding, lighting circuits, socket circuits, and heating circuits where required. Every garden room installation is fully certified under Part P and backed by our 12 month minimum quality guarantee.

Orangeries & Conservatories

Orangeries and conservatories have specific electrical requirements — particularly around outdoor rated fittings, RCD protection for circuits in proximity to water features or external doors, and underfloor heating circuits which are increasingly specified in premium orangery installations across Chelsea and South West London. Our electricians design every orangery and conservatory electrical installation to BS7671 18th Edition standards, ensuring full compliance with the additional requirements that apply to these specific extension types.

One of the most common concerns homeowners have when planning an extension is how to coordinate the different trades involved — and where the electrician fits into the build programme. Chelsea Electrical work alongside builders and project managers across Chelsea and South West London every day — and we understand exactly how to integrate our work into your build schedule without causing delays, disputes, or disruption.

Before the Build Begins

The best time to involve your electrician is before your builder breaks ground — not after. At the pre-build stage we carry out a free survey of your existing installation, assess your consumer unit capacity, discuss your electrical requirements for the new space, and provide a clear fixed price quote covering all new wiring works. We also liaise directly with your architect or builder to ensure the electrical design is integrated into the build drawings from the outset — avoiding costly last-minute changes to cable routes, socket positions, or circuit requirements during the build.

First Fix

First fix is the stage where all new cabling is installed — running cables through walls, floors, and ceilings before plastering begins. This is the most critical stage for coordination with your builder — our electricians need access to the structure before it is closed in. We work directly with your builder to agree the first fix programme, attend on time, and complete all cabling efficiently so the build programme stays on schedule. Every cable route is agreed and documented before first fix begins so there are no surprises on the day.

Second Fix

Second fix takes place once plastering and decoration is complete — this is when all visible elements are fitted, including sockets, switches, light fittings, and accessories. Second fix is a cleaner, less disruptive process than first fix and is typically completed in one to two days depending on the size of the extension. We coordinate directly with your builder or decorator to confirm the second fix programme and ensure the electrical installation is completed and certified before your snagging inspection.

Part P Certification & Sign-Off

Once second fix is complete, every circuit is tested comprehensively to BS7671 18th Edition standards and your Part P certificate is issued. This is the document your building control inspector requires before your extension can be formally signed off — and as a Part P registered electrical business, Chelsea Electrical handle all certification and building control notification on your behalf. Your extension cannot be legally signed off without Part P of the Building Regulations — and we make sure it is always in place before your completion date.

Every new wiring installation we carry out is a comprehensive, fully certified project — not just a few sockets and a light fitting. Here is exactly what is included in every extension wiring installation:

Consumer Unit Capacity Assessment

Before any new wiring begins, we assess your existing consumer unit to confirm it has sufficient capacity to support the additional circuits required for your extension. If an upgrade is required we will tell you honestly and provide a clear fixed price quote for both the consumer unit upgrade and the new wiring installation together. Find out more about our fuse board upgrade service in Chelsea.

New Circuit Design & Planning

We design every new circuit layout around your specific requirements — socket positions, lighting design, dedicated appliance circuits, heating circuits, and any specialist requirements such as smart home integration or outdoor electrics. Every circuit is designed to BS7671 18th Edition standards before first fix begins — ensuring the installation is right first time with no costly alterations required during the build.

First Fix Cabling

All new cables are installed throughout the extension structure during first fix — run through walls, floors, and ceilings as required and routed to protect the cables from damage during the remainder of the build. Every cable route is planned in advance and documented so second fix can be completed efficiently once decoration is finished.

Second Fix Installation

Once plastering and decoration is complete, all visible elements are fitted — sockets, switches, light fittings, and accessories — to a clean, consistent finish throughout the extension. We use quality accessories throughout and will always match the existing specification in your property where possible.

Full Testing & Certification

12 Month Minimum Quality Guarantee

Every new wiring installation we carry out is backed by our 12 month minimum quality guarantee from the date of completion — giving you complete peace of mind that your extension electrics are installed to the standard we promised, and that we stand behind every circuit, every connection, and every fitting we install.

One of the most important questions to answer before any extension wiring begins is whether your existing consumer unit has sufficient capacity to support the additional circuits your new space requires. Adding new circuits to an already full or near-capacity consumer unit is not safe — and it is not something a NAPIT registered electrician will do.

If our assessment identifies that a consumer unit upgrade is required, we provide a clear fixed price quote for both the upgrade and the new wiring installation together — with both jobs completed by the same team, at the same time, as efficiently as possible.

Find out more about our fuse board upgrade service in Chelsea — or call us on 02034 886942 and we will assess your property's requirements at no charge.

The decisions you make about your extension's electrical installation before the build begins will determine how functional, future-proof, and valuable that space is for years to come. Moving a socket after plastering costs significantly more than positioning it correctly during first fix — and adding a circuit after completion can mean lifting floors and chasing walls that have already been decorated. If you are still at the early stages of your project, the Planning Portal provides comprehensive guidance on extension planning permission requirements. Here is what our NAPIT registered electricians recommend thinking about before your build begins:

Socket & Switch Positioning

Think carefully about how you will use the new space and where you will need power. A kitchen extension needs sockets at worktop height, above and below the worktop, and dedicated circuits for fixed appliances. A home office needs multiple desk-height sockets, USB charging points, and ethernet connections. A garden room needs weatherproof outdoor sockets on the exterior. Getting socket and switch positions right at the design stage costs nothing — changing them after plastering costs significantly more.

Lighting Design

Lighting design is one of the most overlooked elements of an extension electrical installation — and one of the most impactful on the finished result. Think about the layers of light you need in the new space — ambient, task, and accent — and design separate lighting circuits for each zone. Dimmer-compatible circuits, recessed downlights, pendant positions, and external lighting all need to be planned and cabled during first fix. Our electricians will always discuss your lighting requirements at the survey stage and advise on the most effective and energy-efficient solution.

EV Charger Circuit

If you do not currently have a home EV charger — or if you are planning to get one in the future — an extension project is the perfect opportunity to install a dedicated EV charger circuit at the same time as your extension wiring. Adding a dedicated circuit during first fix costs a fraction of what it would cost to install separately after completion. Find out more about our EV charger installation service in Chelsea.

Smart Home Integration

If you are planning smart lighting, smart heating controls, or a home automation system in your extension, the wiring infrastructure needs to be planned and installed during first fix — not retrofitted afterwards. Our electricians are experienced in wiring for smart home systems across Chelsea and South West London and will advise on the most practical and future-proof approach for your specific project and budget.

Underfloor Heating

Electric underfloor heating is increasingly specified in extension projects across Chelsea and South West London — particularly in kitchen extensions, orangeries, and ground floor living spaces. A dedicated underfloor heating circuit needs to be planned and installed during first fix alongside your other new circuits. Our electricians will advise on the correct circuit specification for your chosen underfloor heating system at the survey stage.

Outdoor Electrics

An extension project often creates opportunities to improve your outdoor electrical installation at the same time — external lighting, weatherproof socket outlets, garden power supplies, and security lighting can all be installed alongside your extension wiring at significantly less cost than a separate installation. Our electricians will always discuss your outdoor electrical requirements at the survey stage and include them in your fixed price quote where required.

Future Proofing

The most cost-effective electrical installation is one that anticipates future needs as well as current ones. Installing additional consumer unit ways, spare conduit runs, or extra circuits during first fix costs very little compared to the cost of adding them after completion. Our electricians will always advise on practical future-proofing measures at the survey stage — ensuring your extension electrics serve your home as effectively in ten years as they do on the day they are installed.

The cost of new wiring for an extension depends on the type and size of the extension, the number of circuits required, the complexity of the cable routes, the condition of your existing consumer unit, and the specification of accessories you choose. Every project is different — and any electrician who quotes you a firm price without surveying your property is either guessing or cutting corners.

What Affects the Cost of Extension Wiring in Chelsea?

Call us or complete the form below and we will arrange your free survey at a time that suits you and your builder.

Choosing the right electrician for your extension is not just about finding someone who can wire a socket. Your extension electrician needs to understand build programmes, coordinate with other trades, meet building control requirements, and deliver a finished installation that is safe, certified, and exactly what you planned — on time and on budget.

Every new wiring installation we carry out is led by a NAPIT registered, time-served electrician with a minimum of 10 years hands-on experience — overseen by our lead engineer who brings 26 years of residential electrical expertise to every project. We have been wiring extensions across Chelsea, Knightsbridge, Belgravia, South Kensington, and the surrounding areas of South West London for years — working alongside builders, architects, and project managers who trust us to deliver on time, every time.

For all residential electrical services across Chelsea and South London visit our electricians in Chelsea homepage.

We are based in Chelsea and carry out new wiring installations for all types of residential extension across South West London. If you are unsure whether we cover your area, call us on 02034 886942 and we will confirm immediately.

Chelsea

Chelsea is our home town and where the majority of our extension wiring projects are carried out. We cover every area of the town including the King's Road, Cheyne Walk, Sloane Square, and the surrounding streets. Chelsea has seen significant residential extension activity in recent years — with homeowners across SW3 choosing to extend rather than move in the current property market.

South Kensington & Brompton

We carry out new wiring installations for extensions across South Kensington and Brompton. This area has a high proportion of Victorian and Edwardian properties where single storey kitchen and living room extensions are particularly common — and where consumer unit upgrades are frequently required alongside the new wiring installation.

Knightsbridge & Belgravia

Knightsbridge and Belgravia are among our most active areas for extension wiring projects — particularly among homeowners in larger period townhouses where double storey extensions and loft conversions are increasingly common. We cover both neighbourhoods and surrounding residential roads throughout.

Kensington & Earls Court

We carry out new wiring installations for extensions across Kensington and Earls Court. This area has a diverse housing stock — from Georgian and Victorian townhouses where loft conversions and rear extensions are common, to mansion block conversions where garden rooms and garage conversions are increasingly popular.

Pimlico & Fulham

We cover Pimlico and Fulham. This area has a significant number of period and larger properties where extension projects are common — and where older consumer units frequently require upgrading alongside the new extension wiring.

Chelsea Harbour

We cover Chelsea Harbour across the southern part of our service area. No travel supplement applies for properties within this area.

Surrounding Areas

We also cover West Brompton, Battersea, Parsons Green, and all towns and areas within approximately 15 miles of Chelsea. Travel supplements may apply depending on distance — we will always confirm this at the time of quoting and will never add charges without prior agreement.

Not sure if we cover your area? Complete the form below and we will confirm immediately.

Your questions answered honestly — by a NAPIT registered, time-served local electrical business with over 14 years carrying out new wiring installations for extensions across Chelsea  and West London.

Still have a question we have not answered? Call us today and speak directly with one of our experienced Woking based electricians — no jargon, no obligation, just straight honest advice about your extension wiring project.

Ready to get your extension electrics planned, priced, and in the hands of a NAPIT registered electrician who will deliver on time and on budget? Complete the form below and we will get back to you within 1 hour — or call us directly on 02034 886942 to speak to an experienced local electrician today.

Every enquiry is handled personally by our team. No automated responses, no passing your details to third parties — just a straight, honest conversation with a time-served electrician who understands extension projects inside out.