When should I do my first fix electrical?

First fix electrical should happen after the building shell is watertight and structural work is complete, but before insulation, vapour barriers, and plasterboard go up. On a typical domestic extension or new build, the sequence is: structural frame and roof complete, windows and external doors fitted, first fix plumbing (hot and cold pipes, waste), first fix electrical (cables, back boxes, consumer unit connections), insulation, plasterboard. On a rewire in an existing property, first fix means running new cables before the plasterer makes good. Always confirm your slot with the builder or project manager at least 2 weeks in advance — if you turn up and the plasterboard is already going up, you have a problem.

Who should go first — electrician or plumber?

On most domestic projects, the plumber goes first for first fix because their pipes and waste runs are larger and less flexible than electrical cables. Plumbing pipes need gravity falls and cannot be bent as easily, so they get priority on routes through joists and stud walls. However, this is not a hard rule — it depends on the specific project. The best approach is to meet the plumber on site before first fix starts and agree: joist drilling positions (electrical notches at the top, plumbing at the centre — in accordance with building regulations), shared stud walls, and bathroom layouts. If you both need to cross the same joist, the plumber takes the centre (within the safe drilling zone) and you take the top.

What if the builder damages my cables during construction?

First, document the damage with photos immediately and note the date, location, and nature of the damage. Notify the site manager or main contractor in writing (email or message) within 24 hours. Do not simply repair and move on — you need a record for two reasons: (1) you should be paid for the repair work, and (2) if the cable damage is not your fault, you do not want to be held responsible later if there is an issue. If the cable was installed in a safe zone (as defined in BS 7671) with appropriate mechanical protection, and the builder drilled or nailed through it, liability clearly falls on the builder. If your cable was outside a safe zone and not mechanically protected, you may share responsibility. Always install within safe zones and use cable covers or conduit in high-risk areas.

How do I coordinate with the plasterer?

The plasterer needs to know: where all your back boxes are (so they can plaster up to them, not over them), where cables enter the wall (so they do not fill your conduit entries with plaster), and that all your cables and back boxes are fully secured before they start. Before the plasterer begins, walk the job and check: all back boxes are at the correct depth for the chosen plaster thickness (typically 12 to 13mm for skim on plasterboard, 15 to 20mm for multi-coat on brick), all cables are clipped securely and will not be displaced by plastering, and any surface-mounted conduit or trunking is complete. A 10-minute walk-around with the plasterer saves hours of problems later.

What are safe zones for cable routing?

BS 7671 Regulation 522.6 defines safe zones where cables in walls should be installed to reduce the risk of damage from nails, screws, and fixings. The safe zones are: horizontally within 150mm of the top of the wall or partition, horizontally within 150mm of a finished floor, vertically within 150mm of the angle of two walls, and within the zone running horizontally or vertically from an accessory (socket, switch, etc.) on either side. Cables installed within these zones are assumed to be protected by their position. Cables outside safe zones must have additional mechanical protection (such as earthed metal conduit, steel capping, or RCD protection on the circuit). Always install within safe zones where possible and use cable covers where you cannot.

How do I handle scheduling conflicts with other trades?

Scheduling conflicts are inevitable on building sites. The key is to communicate early and in writing. At the start of a project, ask for the programme (schedule) and identify your first fix and second fix windows. Two weeks before your slot, confirm with the site manager that the preceding work is on track. If your slot is moved, get the new date in writing and confirm that you can accommodate it. If multiple trades need the same space at the same time, propose a solution: "I can do the upstairs while the plumber works downstairs" or "I need 2 hours clear access in the kitchen for the consumer unit — can we schedule that for first thing Tuesday?" Being flexible and solutions-oriented wins you repeat work from builders.

Should I charge extra if I have to work around other trades?

If the original quote assumed clear access and you now have to work around other trades (which slows you down), you are entitled to claim for the additional time. On a fixed-price domestic job, this is a grey area — it depends on whether your quote specified clear access. On commercial subcontracts, variations for restricted access are standard. The best approach is to specify in your quote: "This price assumes clear, unobstructed access to all areas during first fix and second fix. If access is restricted by other trades, additional time will be charged at £X per hour." This sets the expectation upfront and avoids awkward conversations later.

SITE GUIDE

Working with Other Trades: Coordination, Timing, and Protecting Your Work

First fix timing, working with plumbers and builders, protecting your cables, communication, and handling disputes. The practical guide to multi-trade coordination for electricians.

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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.

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Key Takeaways

1First fix electrical must happen after the structural shell is complete but before insulation and plasterboard go up. If you miss your window, you are either chasing finished walls (expensive and ugly) or holding up the project.
2Coordinate with plumbers before first fix — agree on routes through joists, positions of boiler connections, underfloor heating manifold locations, and bathroom fan/shaver socket positions. Whoever gets there first should not block the other trade.
3Protect your cables. Run cables through safe zones (as defined in BS 7671 Regulation 522.6) and use mechanical protection where required. Label cable positions clearly before plasterboard goes up. Damage caused by other trades is YOUR liability if the cable was not installed correctly.
4Communicate your schedule in writing — a quick message in the group chat or email confirming when you need access and what needs to be done before you arrive. Verbal agreements on building sites are forgotten within minutes.
5If another trade damages your work, document it immediately with photos and notify the site manager or main contractor in writing. Do not just fix it silently — you lose your ability to claim for the extra work.

01 · Site Guide

Working with Other Trades: Coordination Is Everything

On any project involving more than one trade — which is most projects — your work will overlap with plumbers, builders, plasterers, carpenters, decorators, and others. How well you coordinate determines whether the project runs smoothly or descends into finger-pointing and delays.

Poor coordination leads to cables being damaged, access being blocked, work being ripped out and redone, and relationships being destroyed. Good coordination means agreeing routes, respecting timings, protecting each other's work, and communicating clearly.

This guide covers the practical realities of working alongside other trades on both domestic and commercial projects — from first fix timing to protecting your cables to handling disputes when things go wrong.

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02 · Site Guide

First Fix Timing: Get Your Slot Right

Typical Domestic First Fix Sequence

1Structural work complete — walls, roof, windows, external doors

2First fix plumbing — hot/cold pipes, waste runs, underfloor heating pipes

3First fix electrical — cable runs, back boxes, consumer unit wiring

4Insulation — cavity, stud wall, and loft insulation

5Plasterboard and plastering

6Second fix — all trades fit their final accessories and fittings

If you miss first fix: You either have to chase finished walls (expensive, messy, and the customer will not be happy) or surface-mount cables (which may not be acceptable). Always confirm your first fix date at least 2 weeks in advance and chase the week before.

03 · Site Guide

Working with Plumbers

Coordination Points

Boiler connection — agree position of fused spur and controls wiring
Unvented cylinder — immersion heater circuit and wiring centre position
Underfloor heating — manifold and thermostat wiring positions
Bathroom — extractor fan, shaver socket, heated towel rail positions
Kitchen — dishwasher, washing machine, and waste disposal FCU positions
Outside tap — may need a frost thermostat or trace heating connection

Watch Out For

Plumbing pipes clipped over your cables — ask them to route around
Water leaks onto electrical connections — report immediately
Joist drilling conflicts — agree zones before either of you starts
Bonding — supplementary bonding in bathrooms, main bonding of gas/water
Unvented cylinders need specific controls wiring — confirm spec with plumber

04 · Site Guide

Working with Builders and Bricklayers

Mark your cable routes before bricklaying and plastering. Use cable markers, photographs, or a simple sketch showing cable positions relative to fixed points. This protects you if a builder later drills through a cable and claims they did not know it was there.
Agree chase sizes and routes before the builder cuts them. If the builder is chasing walls for you, specify the depth (minimum 25mm for twin and earth in capping), width, and route. Supervise if possible — a builder who chases too deep in a load-bearing wall creates a structural problem.
Ducting and conduit before concrete floors are poured. If you need cables under a concrete floor, get your conduit or ducting in before the pour. Once the concrete is down, you cannot retrofit cables without breaking it up.
Lintels and steels. Cable routes that cross above windows and doors will encounter lintels and steel beams. Plan your route to avoid drilling through structural steel — route above, below, or around.

05 · Site Guide

Working with Plasterers

Before Plasterboard Goes Up

Check all cables are clipped, all back boxes are positioned correctly, all cable entries are clear, and all first fix is complete. Once plasterboard is up, you cannot access anything without pulling boards off.

Back Box Depth

Back boxes must be set to the correct depth for the finished plaster surface. For plasterboard with skim (approximately 13mm total), the front edge of the back box should sit 13mm behind the face of the stud. If the plasterer has to build up around proud back boxes or your boxes are recessed too deep, second fix will be a nightmare.

Plaster in Back Boxes

The most common frustration: the plasterer fills your back boxes with plaster. Use box blanks or tape over your back boxes before the plasterer starts. It takes 5 minutes and saves hours of chiselling plaster out of boxes during second fix.

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06 · Site Guide

Protecting Your Cables from Damage

Install within safe zones (BS 7671 Reg 522.6) — horizontally within 150mm of the ceiling or floor, vertically within 150mm of corners, and within the zone running directly up or across from accessories.
Use cable covers in chases — galvanised steel capping over cables in wall chases provides mechanical protection and satisfies the requirement for earthed metallic covering in safe zones.
Photograph cable routes — before plasterboard or plaster covers your cables, photograph every route. These photos are invaluable for second fix, future alterations, and dispute resolution if someone damages a cable.
Use joist notching guards — metal plates over notches in joists prevent nails and screws from penetrating cables when floorboards are refixed.

07 · Site Guide

Communication and Scheduling

Most problems between trades come down to poor communication. A 2-minute message can prevent a 2-day problem.

Use the site WhatsApp group. Most multi-trade projects have a group chat. Use it to confirm dates, flag issues, and share photos of progress. If there is not one, create one.
Confirm your schedule in writing. "I will be on site Monday and Tuesday for first fix. I need clear access to all rooms. Please ensure first fix plumbing is complete before I arrive." This sets expectations and gives you a record if things go wrong.
Flag problems immediately. If you arrive on site and the conditions are not what was agreed (plumbing not done, walls not ready, access blocked), notify the builder or project manager immediately in writing. Do not just turn around and go home — communicate.

08 · Site Guide

Handling Disputes with Other Trades

Do

Document damage with timestamped photos
Notify the site manager or main contractor in writing
Propose a solution along with the problem
Charge for repair work if the damage was not your fault
Keep records for every project — they protect you

Do Not

Fix damage silently and absorb the cost
Confront other trades aggressively on site
Damage another trade's work in retaliation
Walk off site without communicating
Discuss disputes in front of the customer

09 · Site Guide

For Electricians: Be the Trade Everyone Wants to Work With

The electricians who get the most repeat work from builders and main contractors are the ones who communicate clearly, turn up when they say they will, protect other trades' work, and solve problems instead of creating them. Your technical skill gets you the first job — your professionalism gets you every job after that.

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Frequently Asked Questions About Working with Other Trades

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Working with Other Trades: Coordination, Timing, and Protecting Your Work

Key Takeaways

Working with Other Trades: Coordination Is Everything

Get the BS 7671 A4:2026 Cheat Sheet — free

First Fix Timing: Get Your Slot Right

Typical Domestic First Fix Sequence

Working with Plumbers

Coordination Points

Watch Out For

Working with Builders and Bricklayers

Working with Plasterers

Before Plasterboard Goes Up

Back Box Depth

Plaster in Back Boxes

Try Elec-Mate free for 7 days

Protecting Your Cables from Damage

Communication and Scheduling

Handling Disputes with Other Trades

Do

Do Not

For Electricians: Be the Trade Everyone Wants to Work With

Schedule and manage multi-trade projects

Frequently Asked Questions About Working with Other Trades

When should I do my first fix electrical?

Who should go first — electrician or plumber?

What if the builder damages my cables during construction?

How do I coordinate with the plasterer?

What are safe zones for cable routing?

How do I handle scheduling conflicts with other trades?

Should I charge extra if I have to work around other trades?

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