House Wiring Colours UK – Old vs New Wiring Explained

UK House Wiring Colour Codes: A Quick Guide to Understanding Them Whether you are a homeowner undertaking minor electrical work, such as the installation of a light, a DIY enthusiast, or just someone who wants to know their home’s electrical system better, it is important to know the appropriate wire color codes. This guide highlights the current UK wiring color codes, how they’ve evolved through the years, and what you should know when working with wiring in and around the home.

Always take electrical safety seriously. Poor wiring can pose dangerous risks, such as electric shocks and fires, as well as damage to expensive appliances. Knowing what the color coding system means when it comes to UK electrical installations can help you make decisions about your home and know when to call in a professional.

UK Wiring Colour Changes: What You Need to Know

The UK has undergone significant changes to its electrical wiring colour codes over the years. The most recent major change came in 2006 when the UK aligned with European standards. This update created a safer, more standardized approach to electrical wiring but also means that many UK homes contain both old and new colour systems.

Current UK House Wiring Colours (Post-2006)

The current standard for fixed wiring in the UK follows these colour codes:

• Live (Phase) wire: Brown
• Neutral wire: Blue
• Earth/Ground wire: Green and Yellow striped

For three-phase systems, the additional live wires are:

• Second phase (L2): Black
• Third phase (L3): Grey

These changes were implemented through the 17th Edition of the IET Wiring Regulations (BS 7671:2008) and have been maintained through subsequent updates. The harmonization with European standards has improved safety and reduced confusion for electricians working across different countries.

Old House Wiring Colours in the UK (Before 2006)

If your home was wired before 2006, you might encounter these older colour codes:

• Live wire: Red
• Neutral wire: Black
• Earth/Ground wire: Green and Yellow striped

For three-phase systems under the old standard:

• Phase 1: Red
• Phase 2: Yellow
• Phase 3: Blue

Understanding both systems is important when working with existing installations. Many homes in the UK have a mixture of both colour systems, especially if they’ve had partial rewiring or extensions added after 2006.

Read: Connecting Solar Panels to House Wiring in the UK: Complete Guide

Why the Colour Change Happened

The change to the new colour system wasn’t arbitrary. It was part of a wider European harmonization process designed to:

1. Improve safety by creating a consistent standard across Europe
2. Reduce confusion for electricians working in different countries
3. Accommodate the increasing complexity of modern electrical systems
4. Address certain safety concerns with the old system

One key improvement was changing the neutral wire from black to blue, as black was sometimes difficult to distinguish in poor lighting conditions. Similarly, the change from red to brown for live wires created a clearer visual distinction.

Read: Electrical Wiring Diagrams for Houses: Layouts, Components, and Safety Tips

UK Electrical Cable Types and Their Colour Coding

Standard Single-Phase Household Cables

Twin and Earth Cable

This is the most common cable used in UK homes for ring mains, lighting circuits, and fixed appliances.

• Construction: Contains two insulated conductors (live and neutral) plus an uninsulated earth wire
• Modern colours: Brown (live), Blue (neutral), Green/Yellow (earth)
• Old colours: Red (live), Black (neutral), Green/Yellow (earth)
• Common sizes: 1mm² (lighting), 2.5mm² (power), 6mm² (cookers/showers)
• Typical uses: Socket outlets, lighting circuits, fixed appliances

The size of the cable used depends on the circuit’s current rating and the expected load. For example, 2.5mm² cable is standard for 13A socket circuits, while 6mm² is used for high-current appliances like electric cookers.

Three-Core and Earth Cable

Used for two-way switching of lights and other applications requiring an additional conductor.

• Modern colours: Brown, Black, Grey, Green/Yellow (earth)
• Old colours: Red, Yellow, Blue, Green/Yellow (earth)
• Common sizes: 1mm² (lighting), 1.5mm² (heavier lighting)
• Typical uses: Two-way light switches, three-way lighting controls

This cable type allows for more complex control systems, especially for lighting where you might want to control a light from multiple switches.

Flex Cables (Appliance Cables)

These flexible cables connect appliances to power outlets.

• Two-core (no earth): Brown (live), Blue (neutral)
• Three-core (with earth): Brown (live), Blue (neutral), Green/Yellow (earth)
• Common sizes: 0.5mm² (lamps), 0.75mm² (general appliances), 1.5mm² (heavier appliances)
• Typical uses: Lamps, televisions, kitchen appliances

The flexibility of these cables makes them suitable for movable appliances, but they’re not designed for fixed installations within walls or ceilings.

Special Purpose Cables

Heat-Resistant Cables

Used for high-temperature applications:

• Construction: Often silicon-insulated
• Colours: Standard brown/blue/green-yellow, but with heat-resistant insulation
• Uses: Connecting to heating appliances, ovens, boilers

Low Smoke Zero Halogen (LSZH) Cables

These cables produce minimal smoke and no halogen gases when exposed to fire:

• Colours: Standard colour coding applies
• Uses: Commercial buildings, escape routes, public buildings

Armoured Cables

Used for outdoor or underground installations:

• Construction: Standard cores with metal armour and outer sheath
• Colours: Standard internal core colours
• Uses: Garden supply, outbuildings, underground runs

Safety Considerations When Working with Different House Wiring Colours UK

Mixed Wiring Systems

Many UK homes have a mixture of old and new wiring colours, particularly in homes that have had partial rewiring or extensions. This creates potential safety risks.

When working with mixed systems:

• Always test wires with a voltage tester before touching them
• Don’t rely solely on colour for identification
• Label cables clearly when mixing systems
• Consider updating old wiring to new standards when possible

When connecting old and new systems together, junction boxes should be used with clear labeling to indicate the function of each wire regardless of its colour.

Common Confusion Points

UK vs. European Standards While the UK has aligned with European standards, there are still some differences in certain applications and specialist systems. For example, some industrial applications may have specific colour codes for control circuits that differ slightly.

Three-Phase Confusion The change from Red/Yellow/Blue to Brown/Black/Grey for three-phase systems can cause confusion in industrial or commercial settings. This is especially true in buildings with mixed-age systems.

Earth Wire Consistency One helpful point is that the earth wire colour (green and yellow striped) remained the same through the colour code change, providing some consistency between old and new systems.

Specific Safety Hazards to Watch For

Reversed Live and Neutral This dangerous situation can make appliances appear to be off when they’re actually still connected to the live supply. Always check connections carefully.

Missing Earth Connections Some older UK properties may have lighting circuits with no earth wire. These require special attention and may need upgrading.

Damaged Insulation Over time, cable insulation can degrade, making colour identification difficult and creating shock hazards.

How to Identify UK Wiring Colours Correctly

Visual Identification

While colour is the primary identification method, you should also consider:

• Cable marking: Modern cables often have printed information
• Cable position: Where the cable is located in the circuit can help identify its purpose
• Cable size: Different sized cables are used for different purposes
• Cable construction: The physical construction of the cable can provide clues

Testing Methods

Never rely solely on visual identification. Always test using:

• Voltage tester: To verify if a wire is live
• Continuity tester: To confirm connections
• Multimeter: For detailed testing
• Two-pole tester: For confirming both presence and absence of voltage

Circuit Tracing

For complex or unclear installations:

• Cable tracers: Electronic devices that can trace cables through walls
• Circuit analyzers: Can identify which circuit a cable belongs to
• Labeling systems: Commercial and DIY options for clear identification

UK Wiring Colour Standards for Different Applications

Domestic Fixed Wiring

Standard domestic applications follow the basic colour codes:

• Power circuits: Brown/Blue/Green-Yellow
• Lighting circuits: Brown/Blue/Green-Yellow
• Ring final circuits: Typically 2.5mm² cable with brown/blue/green-yellow
• Radial circuits: Used for dedicated appliances or specific areas

The UK primarily uses ring final circuits for power outlets, which is different from many other countries that use radial circuits. This affects how cables are routed and connected.

Specialised Applications

Bathroom and Kitchen Wiring The same colour codes apply, but special IP-rated (Ingress Protection) fixtures and RCD protection are required. These rooms are considered “special locations” under the wiring regulations due to increased risks from water.

Garden and Outdoor Wiring Uses standard colours but requires special cables rated for outdoor use and additional protection:

• Armoured cable (often called SWA – Steel Wire Armoured)
• Minimum burial depths (typically 450mm under pathways, 600mm under driveways)
• RCD protection is mandatory

Consumer Units (Fuse Boxes) Modern consumer units use colour coding for different circuit types:

• Red for emergency circuits
• Blue for standard circuits
• Green for special circuits

Modern consumer units must provide RCD protection for all circuits, with RCBO devices (combined RCD and circuit breaker) becoming increasingly common.

Commercial and Industrial Applications

While still following the same basic colour codes, commercial and industrial installations often include:

• Three-phase supplies: Brown/Black/Grey with Blue neutral
• Control circuits: Various colours for different functions
• Low voltage systems: Specific colours for SELV (Safety Extra Low Voltage) circuits
• Data cabling: Completely separate colour systems

Regulatory Requirements and Building Regulations

All electrical work in the UK must comply with:

• BS 7671: Requirements for Electrical Installations (IET Wiring Regulations)
• Part P of Building Regulations: Covers safety of electrical installations in dwellings
• Electricity at Work Regulations 1989: Covers workplace electrical safety

The current edition of the wiring regulations is the 18th Edition (BS 7671:2018), with amendments. These regulations are updated regularly, so it’s important to check the latest requirements.

DIY vs. Professional Work

Certain electrical work must be carried out by qualified professionals:

• New circuits
• Work in special locations (bathrooms, kitchens, outdoors)
• Consumer unit replacements
• Any work that requires notification under Part P

For DIY enthusiasts, “like-for-like” replacements may be permitted, but always check current regulations. Examples of permitted DIY work might include:

• Replacing a standard light fitting (not in a bathroom)
• Replacing a damaged socket with an identical one
• Adding a spur to an existing circuit (in some circumstances)

Certification Requirements

Professional electrical work should be accompanied by:

• Electrical Installation Certificate (EIC): For new installations
• Minor Electrical Installation Works Certificate (MEIWC): For additions to existing installations
• Electrical Installation Condition Report (EICR): For periodic inspections

These certificates should be retained as they may be required when selling a property or for insurance purposes.

Comparing UK and International Wiring Colour Standards

UK vs. European Standards

The UK has largely aligned with European standards, but some differences remain in specific applications. For example, the UK uses ring final circuits for power outlets while many European countries use radial circuits.

UK vs. US Standards

The US uses a completely different system:

• Hot (Live): Black (or Red/Blue for additional phases)
• Neutral: White or Grey
• Ground (Earth): Green or Bare Copper

This is important to know if using imported electrical equipment or if you’re familiar with US systems. Appliances designed for US electrical systems often cannot be used directly in the UK due to different voltage standards (230V in UK vs. 120V in US).

UK vs. Australian Standards

Australia uses:

• Active (Live): Brown (previously Red)
• Neutral: Blue (previously Black)
• Earth: Green/Yellow

Australia followed a similar transition to the UK, moving from the old red/black to the new brown/blue system.

Practical Guide to Working with UK Wiring Colours

Tools You’ll Need

• Voltage tester: Non-contact types are safest
• Screwdrivers: Insulated, various sizes
• Wire strippers: For preparing cable ends
• Electrical tape: In various colours for marking
• Cable detector: For finding wires in walls
• Circuit analyzer: To identify circuits safely
• Insulation resistance tester: For checking cable condition
• Terminal screwdrivers: Often smaller than standard types

Step-by-Step Process for Safe Wiring

1. Turn off power: Always at the consumer unit/fuse box
2. Lock off: If possible, use a lock-off device to prevent accidental reconnection
3. Test for power: Verify circuits are dead before working
4. Identify wires: Use colour codes and testing
5. Make connections: Following manufacturer’s instructions
6. Insulate properly: Ensure all connections are properly covered
7. Final testing: Before restoring power
8. Documentation: Record what you’ve done for future reference

Common DIY Electrical Projects

Replacing a Light Fixture

1. Turn off power at the consumer unit
2. Test to ensure power is off
3. Identify wires by colour (Brown = Live, Blue = Neutral, Green/Yellow = Earth)
4. Connect to corresponding terminals on the new fixture
5. Secure all connections and mountings
6. Test before restoring power

Adding a New Socket from an Existing One This might be permitted DIY work in some circumstances:

1. Plan the route and cable requirements
2. Turn off power to the circuit
3. Install the cable between the existing socket and new location
4. Connect to the existing socket as a spur
5. Install the new socket box and connect wires
6. Test thoroughly before use

Remember that any significant changes to electrical circuits may require notification to building control and certification by a qualified electrician.

Dealing with Mixed Wiring Systems

Identifying Old vs. New Systems

Visual clues:

• Cable age and condition
• Consumer unit type and age
• Property age and renovation history
• Cable insulation materials
• Markings on cables
• Circuit breaker vs. fuse protection

Homes built or rewired before 2006 will likely have the old red/black system, while newer properties will have brown/blue. Extensions or partial rewires may contain both systems.

Safe Approaches for Mixed Systems

When extending existing circuits:

• Clearly label junction points where old and new colours meet
• Consider using junction boxes to separate systems
• Document the wiring for future reference
• Use sleeving to identify wire functions
• Consider a complete rewire if the system is very old

When replacing fixtures:

• Test and verify all wires regardless of colour
• Use sleeving or tape to mark wires according to function
• Consider upgrading to fully modern standards
• Take photos before disconnecting for reference

Converting Between Systems

When converting between old and new colours, use this reference:

• Old Red → New Brown (Live)
• Old Black → New Blue (Neutral)
• Green/Yellow remains the same (Earth)

Special Considerations for UK House Wiring

Dealing with Old Fabric-Covered Cables

Many older UK homes have fabric-insulated cables that predate modern standards:

• These often have no colour coding or different systems
• They require special handling and often need replacement
• Professional assessment is recommended
• They may use rubber insulation which degrades over time
• Common in pre-1960s properties

These older systems often lack proper earthing and may use different voltage ratings than modern systems. They are typically considered unsafe by modern standards and should be assessed by a qualified electrician.

Non-Standard Installations

UK homes can have various non-standard installations:

• Lighting circuits with no earth: Common in older properties
• Conduit systems: Metal pipes containing unsheathed wires
• Surface-mounted systems: Visible wiring in protective casings
• Sheathed mineral-insulated cables: Metal-clad cables with different termination requirements
• Unmarked cables: Sometimes found in very old installations

Historical Systems

Some historic UK properties might contain:

• Lead-sheathed cables: Used pre-1960s
• Aluminium wiring: Briefly used in the 1960s-70s
• VIR (Vulcanized India Rubber): Common in early-mid 20th century
• Knob and tube wiring: Very rare but found in some historic buildings

These systems require specialist knowledge and often need complete replacement rather than modification.

Safety Precautions When Working with Electrical Wiring

Before You Start

Essential safety checks:

• Ensure you have the proper knowledge and tools
• Turn off power at the main switch
• Use a voltage tester to verify power is off
• Inform others in the house about the work
• Ensure adequate lighting in the work area
• Wear appropriate PPE (Personal Protective Equipment)
• Have a first aid kit accessible

Emergency Procedures

If you encounter problems:

• Know where your main switch is located
• Have a phone available for emergencies
• Know basic first aid for electrical injuries
• Have a fire extinguisher suitable for electrical fires
• Understand how to safely disconnect power in an emergency
• Have emergency contact numbers readily available

Working Safely

Key safety practices:

• Never work on live circuits
• Use insulated tools
• Work with one hand when possible (to avoid current passing across your chest)
• Remove jewelry and watches
• Use rubber mats or footwear with rubber soles
• Keep the work area dry
• Don’t rush

FAQs

What does the green and yellow wire connect to?

The green and yellow wire is the earth or ground wire. It connects to the earth terminal (usually marked with the earth symbol or “E”) in plugs, sockets, and appliances. This wire provides a safety path for fault currents to protect against electric shock.

Can I connect old and new colour wires together?

Yes, but you must identify them correctly by function, not just colour. Use proper junction boxes and clearly label connections. When connecting old red to new brown (both live) or old black to new blue (both neutral), use appropriate connectors and identification.

Do I need to rewire my house if it has old colours?

Not necessarily. Old colour wiring that’s in good condition is safe to use. However, any new extensions or significant alterations should use the new colours. Consider rewiring if your wiring is over 25-30 years old, regardless of colour code.

What colour is the earth wire in a UK plug?

In a UK plug, the earth wire is green and yellow striped. It connects to the top pin (the earth pin) of the plug.

How can I tell if my house has been rewired to the new standards?

How often should house wiring be checked?

The current recommendation is that domestic electrical installations should be inspected and tested at least every 10 years. For rented properties, this is typically required every 5 years.

Can I mix old and new colour cables in the same circuit?

Yes, but this should be done carefully with proper identification at junction points. It’s generally better to use all new colours when making significant changes.

What should I do if I can’t identify the wire colours?

If colours are faded or unclear, you should test the wires to determine their function. If in doubt, consult a qualified electrician. Never guess when it comes to electrical wiring.

Local Requirements for Electrical Work in the UK

Building Regulations Compliance

All electrical work must comply with UK Building Regulations, specifically Part P which covers electrical safety in dwellings.

For significant work, you’ll need:

• Notification to local building control
• Certification from a qualified electrician
• Registration with a competent person scheme

Different regions of the UK may have slightly different requirements:

• England and Wales: Follow Part P of the Building Regulations
• Scotland: Follow the Building Standards Technical Handbook
• Northern Ireland: Follow Technical Booklet E

Finding Qualified Electricians

Look for electricians registered with:

• NICEIC (National Inspection Council for Electrical Installation Contracting)
• ELECSA
• NAPIT (National Association of Professional Inspectors and Testers)
• SELECT (in Scotland)

Always check credentials and insurance before hiring. Ask for:

• Public liability insurance
• Examples of similar work
• References from previous customers
• Membership of a recognized trade body
• Their process for providing certification

Local Authority Notifications

Some electrical work must be notified to local building control unless done by a registered competent person:

• New circuits
• Consumer unit replacements
• Work in special locations (bathrooms, kitchens)
• Outdoor electrical installations

The process typically involves:

1. Notification before work begins
2. Possible inspection during work
3. Final certification
4. Registration of the work

Conclusion

Understanding house wiring colours UK is essential for safety and compliance. Whether you’re dealing with modern brown/blue or older red/black systems, proper identification and handling of electrical wires is crucial. For most significant electrical work, using a qualified professional is not just recommended but required by law.

The 2006 change to align with European standards has improved safety and consistency, but the transition has created mixed systems in many homes. When working with any electrical installation, remember that safety comes first – always turn off power, test before touching, and work within your competence level.

By following the guidance in this article, you can work safely with your home’s electrical system while maintaining compliance with UK regulations. When in doubt, consult a qualified electrician who can provide expert guidance specific to your situation.

Regular inspection and maintenance of your electrical system, regardless of which colour code it uses, is the best way to ensure ongoing safety and performance. Consider having a professional Electrical Installation Condition Report (EICR) done every 5-10 years to identify any potential issues before they become hazardous.