UK Wiring Colours 2026: Live, Neutral & Earth Colour Codes

Brown is live, blue is neutral, green/yellow is earth — these colours apply to all UK fixed wiring installed since April 2006 and all flexible cables since the 1970s. Before 2006, fixed wiring used red (live) and black (neutral). The table below covers single-phase, three-phase, and pre-2006 colours at a glance.

Understanding UK electrical wiring colours is essential for anyone working with electrical installations — whether you are a trainee electrician, a qualified professional inspecting older properties, or a homeowner checking old wiring. Getting conductor identification wrong can be fatal.

In April 2006, the UK changed its fixed wiring colours to harmonise with European standards. The old red (live) and black (neutral) system was replaced with brown (live) and blue (neutral). This guide explains every colour variation, why the change happened, and the critical safety issues when old and new colours exist in the same installation.

Wiring colour identification is covered in the Level 2 Diploma in Electrical Installations, the 18th Edition course, and is a core competency in 2391 Inspection and Testing.

Single-Phase Fixed Wiring

Since 1 April 2006, all new fixed wiring in the UK must use the following colours:

Three-Phase Fixed Wiring

Three-phase installations use three line conductors plus neutral and earth:

Flexible Cable Colours (Appliance Flex)

Flexible cables — the type found on appliance leads, extension cables, and portable equipment — use the same brown/blue/green-yellow system. However, flexible cable colours changed much earlier than fixed wiring. Appliance flex has used brown (live) and blue (neutral) since the 1970s, so this colour scheme predates the 2006 fixed wiring change by approximately 30 years.

Two-Core and Earth Cable (6242Y)

The most common cable in UK domestic wiring is twin and earth — also known as 6242Y (flat profile). This cable contains two insulated conductors plus a bare copper earth conductor, all enclosed in a flat grey or white PVC outer sheath. The bare earth must be sleeved with green and yellow sleeving at every termination point (e.g. at sockets, switches, and the consumer unit).

Three-Core and Earth Cable (6243Y)

Three-core and earth cable is used for two-way switching circuits. It has three insulated conductors — brown, black, and grey — plus a bare earth. In a two-way switch circuit, the brown conductor is typically the permanent live, while the black and grey are used as strappers (travellers). Because black is used as a switched live in this configuration, BS 7671 requires it to be identified with brown sleeving or tape at each termination.

Single-Phase Fixed Wiring (1976–2006)

For 30 years, UK fixed wiring used the following colours. Many domestic properties still have this colour scheme:

Three-Phase Fixed Wiring (Pre-2006)

Pre-1976 Wiring Colours

Older properties may contain wiring from before the 1976 standardisation. These very old colours were less consistent:

If you encounter wiring from before 1976 — particularly where the earth conductor is bare or has black insulation — the installation is extremely old and likely needs a full rewire. An EICR should be carried out immediately.

The colour change was driven by European harmonisation under IEC 60446 and CENELEC HD 308 S2. The UK was the last major European country still using red/black for fixed wiring. Key facts:

• ✓Amendment 2 to BS 7671:2001 (16th Edition Wiring Regulations) mandated the change
• ✓Transition period: new colours could be used from 1 April 2004
• ✓Old colours were prohibited in new installations from 1 April 2006
• ✓Purpose: avoid confusion when European electricians work in the UK and vice versa
• ✓Fixed wiring colours were the main change — flexible cable colours had already harmonised in the 1970s
• ✓The earth colour (green and yellow) did not change — it has been the same since 1976

The history of wiring regulations covers how BS 7671 has evolved over the decades, including the amendments that introduced the colour change.

UK wiring colours have changed several times over the past century. Understanding the timeline helps electricians date an installation when carrying out inspections and EICRs.

Note the transition period from April 2004 to March 2006: during these two years, both old and new colours were permitted in new installations. After 31 March 2006, only the new harmonised colours could be used in new work.

In real-world electrical work, identifying conductor colours is not always straightforward. Cables deteriorate over time, insulation discolours, and installations may have been modified by multiple electricians over decades. Here are practical tips used by qualified electricians and inspectors.

Never Rely on Colour Alone

BS 7671 is clear: colour is an aid to identification, not a guarantee of function. Always use a voltage indicator (such as a GS38-compliant two-pole tester) to confirm whether a conductor is live before working on it. This is a core part of the safe isolation procedure.

Common Identification Problems

• ✓Discoloured brown insulation can look red in poor lighting — check the cable sheath age (grey PVC = post-1960s)
• ✓Black conductors: in old single-phase wiring, black is neutral. In new three-phase wiring, black is L2 (a live phase). Always test before touching
• ✓Blue conductors: in old three-phase wiring, blue is L3 (live). In new wiring, blue is neutral. The opposite function — test every time
• ✓Bare copper earth conductors in twin-and-earth cable should be sleeved green/yellow at terminations, but this is often missing in older work
• ✓Switch returns and two-way circuits: black conductors used as switched lives should be marked with brown tape or sleeving, but many installers omit this

Conductor Marking at Terminations

BS 7671 Table 51 sets out the required identification for all conductors at termination points. Where the insulation colour does not match the required identification (for example, a black conductor used as a switched live), the conductor must be marked using tape, sleeving, or heat-shrink in the correct colour. This is particularly important in:

• ✓Two-way switch circuits where black or grey conductors carry a switched live
• ✓Intermediate switch circuits with multiple strappers
• ✓Three-phase distribution boards where old and new colours may coexist
• ✓Additions or alterations to existing circuits using old colours

Electricians increasingly work with data and communication cables alongside mains wiring. These have their own colour coding standards:

Cat5e/Cat6 Ethernet (T568B Standard)

The T568B wiring standard uses four twisted pairs with specific colours: white-orange/orange, white-green/blue, white-blue/green, white-brown/brown. This is the most common standard in UK commercial installations. While not covered by BS 7671, many electricians now install structured cabling as part of smart home installations.

Fire Alarm Cables

Fire alarm cables (to BS 5839) use red outer sheathing to distinguish them from standard mains cables. The internal conductor colours are typically red (positive) and black (negative/return). Enhanced fire-rated cables may have additional screening. Mains-powered fire alarm circuits must comply with BS 7671 for their supply cables.

Many properties contain a mixture of old and new wiring colours. This is perfectly legal — existing wiring does not need to be changed. A specific warning notice wherever old and new colours exist in the same installation was required by BS 7671 Regulation 514.14 until that regulation was deleted by Amendment 2:2022. Fitting or retaining the notice remains widely recommended good practice, and you will still find it on most mixed-colour installations.

Where to Place the Warning Notice

• ✓At or near the consumer unit or main distribution board
• ✓At every distribution board in the installation
• ✓The notice must be durable and legible for the life of the installation

For more on consumer units, including when they need replacing and current regulations, see our dedicated guide.

Best Practice for Mixed Installations

• ✓Always use a voltage indicator to identify conductors — never rely on colour alone
• ✓Label every conductor at every termination point
• ✓When extending circuits, new wiring must use the new colours even if the existing circuit uses old colours
• ✓Consider a full rewire if the old wiring is approaching the end of its lifespan (30–40 years for PVC)
• ✓Document all conductor identifications on the electrical installation certificate or EICR

If the old wiring is approaching its end of life, a full domestic rewire may be the safest option. Old wiring also means old earthing and bonding arrangements, which should be inspected at the same time.

The outer sheath of a cable can tell you a lot about its age and type. Recognising different cable sheaths is an important skill for inspection work.

PVC-Insulated and Sheathed (Current Standard)

• ✓White or grey outer sheath (twin and earth)
• ✓Used from the 1960s onwards
• ✓The most common cable in UK domestic installations
• ✓Expected lifespan: 30–40 years
• ✓Known by trade names like "6242Y" (flat twin and earth)

Tough Rubber Sheathed (TRS) Cables

• ✓Black outer sheath
• ✓Found in pre-1960s installations
• ✓Now over 60 years old — well past safe lifespan
• ✓Deteriorates from heat, UV exposure, and overloading
• ✓Rubber insulation becomes brittle and cracks with age
• ✓Should be replaced if found during any inspection or alteration work

Lead-Sheathed Cables

• ✓Found in pre-1950s domestic installations
• ✓Rubber insulation with a lead outer sheath
• ✓Well past expected working life — replacement is essential
• ✓Health risk from lead during removal — specialist disposal required
• ✓Extremely rare in active use, but occasionally found in unmodified older properties

Steel Wire Armoured (SWA) Cable

• ✓Used for outdoor and underground installations
• ✓Multi-layer construction: inner cores, PVC bedding, wire armour, outer sheath
• ✓Three-core colours follow the same standard as fixed wiring (brown, black, grey)
• ✓The armour itself can be used as the circuit protective conductor (CPC) in some circumstances

For more on the regulations that govern conductor identification, see our guide to the 18th Edition Wiring Regulations. For information on testing and verifying conductor identification during inspections, see the electrical testing procedures guide.

If you are dealing with old wiring that needs replacing, our domestic rewire guide covers the full process from first fix to completion. Understanding earthing and bonding is equally important when working with older installations. And if old wiring terminates at an outdated fuse board, see our consumer unit guide for current replacement regulations and costs.

Conductor identification and wiring colour codes are core content in our City & Guilds accredited courses:

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Level 2 Diploma (2365)

Unit 204 covers wiring systems, cable identification, and colour codes in detail with hands-on practical work.

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Inspection & Testing (2391)

Identifying conductor colours during inspection is a core competency tested in the 2391 practical assessment.

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