How many sockets should you plan for a kitchen extension?

Plan far more than feels reasonable on paper. A well-equipped kitchen-diner typically needs 15 to 20 double sockets across worktop runs, islands, and the living-dining zone, plus dedicated connections for fixed appliances. Almost every homeowner who finishes an extension says they wish they had fitted more.

Why does the electrical layout have to be planned before first fix?

Every socket height, dedicated circuit, and lighting position depends on where your fitted units and appliances go, so the room layout has to be final first. Once cables are buried behind plasterboard and screed, moving anything means cutting open finished walls, so the decisions are made on paper, not on site.

Do you need to mark socket heights on an electrical plan?

Yes. Worktop sockets, appliance connections inside base units, and standard room sockets all sit at different heights, and the electrician defaults to standard height unless you tell them otherwise in writing. Writing the height next to every socket on the drawing is what prevents the most common positioning errors.

Can you add floor sockets or island cables after the screed is poured?

No. Any cable that runs through the floor must be in conduit laid before the screed goes down, so island sockets and central floor points have to be decided at planning stage. Retrofitting them later means breaking up a floor that may contain underfloor heating loops.

Should you brief your electrician by phone or with a drawing?

Always with a marked-up drawing plus photographs, never a phone call. A verbal brief leaves the electrician to make assumptions about positions, which is how extractor fans end up blocking wall units and sockets land at the wrong height. The drawing is the contract between what you expect and what gets wired in.

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Phase 6 · First Fix · Task 01 of 06

Electrical Layout Planning

How to plan your socket, switch, and lighting positions before the electrician arrives. Your room layout must be finalised first.

14 min readUpdated 2026Premium

Process infographic showing the electrical layout planning sequence: finalise room layout, map sockets and circuits, plan lighting zones, check consumer unit capacity, then brief the electrician

Prerequisites

Complete this first

Screeding

Get your electrical layout wrong and you'll pay to fix it twice: once to move the cables behind the plasterboard, and again to replaster the wall you just ripped open. Sockets in the wrong position, an extractor fan wired where it blocks a fitted unit, a pendant light over the wrong spot. These aren't rare problems. They're the most common first-fix failures on extension projects, and every single one is preventable with a few hours of planning before your electrician picks up a drill.

This is the planning stage. The actual installation (first-fix electrics) is a separate task that happens after you've completed this exercise. You are the designer here. Your electrician executes your design. If you hand them a vague brief, you'll get a vague result.

Do this first

Your room layout must be finalised before you plan electrical positions. Every socket height depends on where worktops and fitted units go. Every dedicated circuit depends on which appliances you've chosen. Every lighting zone depends on the room layout. If the layout changes after first-fix wiring is buried in the walls, you're looking at expensive rework. Don't start this until your layout drawings are complete.

What this guide covers

01Why This Is a Separate Step
02Socket Positions: Where and How Many
03Dedicated Circuits: What Needs Its Own Feed
04Lighting: Zones, Not Just Lights
05Cables in Screed: The Sequencing Trap
06The Consumer Unit Question
07Part P: What You Must Know
08AFDDs: Recommended, Not Required
09Smart Home Pre-Wiring
10Creating Your Electrical Layout Drawing
11What Your Electrical Quote Should Include
12Common Mistakes
13What This Costs You to Plan

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