UK Wiring Colours For Old and New Cables

When performing any form of electrical work it is absolutely essential that you know what colour wire in an electrical cable should be used for what purpose so that when you need to wire an object up, you connect the right wire to the right terminal.

In this guide you will learn all you need to know about UK wiring colours, and what the old wire colours were changed to and why.

Rules and Regulations for Electrical Work

There are very strict rules on what you can and cannot do in your home in terms of electrical work and for very good reason! Electricity is highly dangerous and if you don’t know exactly what you are doing it’s always best left to the professionals.

In respect to this, other than changing existing socket and switch faceplates, which you are allowed to do yourself, there isn’t a great deal else you can do and anything more substantial will need to be done by a Part P registered electrician. This is the law as stated in the BS7671 Wiring Regulations.

If you choose to ignore this rule then theres a good chance this will invalidate your home insurance and also if you come to sell your home and there are works that have no certificate to cover them, then this can cause major issues.

For the few jobs you can do, if you would like to find ot more about staying safe when working on or around electricity, see our electrical safety project here.

What Have Wire Colours Changed to?

When the change finally came into effect in March 2006 it ensured that in new fixed electrical installations the live wire colour changed to brown from red, the neutral changed to blue from black and the earth remained green/yellow or bare.

In electrical wiring there are essentially 2 common types of cable you will encounter; 2 core and earth and 3 core and earth. 2 core and earth (or twin and earth as it’s also known) is generally used for wiring radial and ring main circuits whereas 3 core and earth is used mostly in 2-way lighting setups.

In terms of why the wire colour change occurred, very simply put, the changes would ensure that fixed cables in your home will (if any new circuits are introduced) carry the same colour wires as any appliance flex and also match wire colours used in Europe.

The colour changes for the 2 common types of cable are as follows:

Wire Colour Changes for 2-Core and Earth Cable

• The live Red becomes Brown
• The Neutral Black becomes Blue
• The Earth wires continue to be Green and Yellow or bare (sheathed when installed)

Wire Colour Changes for 3-Core and Earth Cable (4-Core Cable)

• The live Red becomes Brown
• The additional Yellow conductor becomes Black
• The Neutral Blue becomes Grey
• The Earth wires continue to be Green and Yellow or bare (sheathed when installed)

Wire Colour Changes for 4-Core and Earth Cable (5-Core Cable) or 3-Phase

Less commonly used in homes and more often used in industrial situations for 3-phase electrical installs is the 4-core and earth or 5-core cable.

As the name suggests the cable has 4 main cores and an earth. When the wire colour changes came into effect, 4-core and earth wires changes as follows:

• The live Red becomes Brown
• The Neutral Blue becomes Grey
• The additional Yellow line 2 conductor becomes Black
• The additional Blue line 3 conductor becomes Grey
• The Earth wires continue to be Green and Yellow or Bare or bare (sheathed when installed)

Why Have Wire Colours Changed?

The main reason for the UK wire colour change on the 1st of April 2006 was to ensure that electrical wire colours across the UK and all European countries matched so that the live was brown, neutral was blue and earth would be green/yellow or bare.

As the UK at the time was a European country it was felt that the mismatch in electrical wire colours was confusing and to avoid any potential issues, UK wire colours changed to match the IEC (International Electrotechnical Commission) colours of Europe to create what’s referred to as a “harmonised system”.

Before this change, old wiring colours in the UK for 2-core wire were red = live, black = neutral and earths are either bare or yellow and green, whereas with 3-core cable live = red, blue = neutral, additional = yellow and earth either bare or yellow and green.

It’s important to state that the change in wire colour only applies to new installations and not existing ones, so many properties built before this date will still feature wires with the old colour scheme.

When the United Kingdom agreed to adopt the blue for neutral, brown for live and green/yellow for earth in flexible cables and flexible cords usually used for non-fixed installations e.g. appliances such as fridges, washing machines etc. no move was made to harmonize the colours for fixed installations in homes and other structures.

However at this time the rest of Europe was changing over very quickly.

In 1999 it became apparent that a new European standard for wiring and cable colours meant that the UK would have to catch up pretty quickly and change fixed cable colours to suit.

Obviously millions of existing cables sat on the shelves of electrical wholesalers etc. had the old red, black and yellow/green wire colours, so to limit the number of new installations still using old colours and also possibly mixing new colours, it was agreed that the new wire colour scheme could start to be used from the 31st May 2004, even though it wasn’t compulsory until 31st March 2006.

In terms of the legal requirements and guidance, the changes for wire colours were published in 2004 by the Institute of Electrical Engineers, the IEE (later changed to the IET or Institution of Engineering and Technology) in Amendment 2 of British Standard 7671:2001 16th edition wiring regulations.

The amendment specified the use of new cable colours for all new fixed wiring electrical installations in the UK. As mentioned these new colours are sometimes referred to as Harmonized colours as they brought the UK more closely in line with practices in mainland Europe.

Complete details on the changes can be found on the IET web site.

What are the Different Types of Wire and Cable?

There are several different types of wire and cable that are used in domestic and industrial wiring situations and they include 2-core, 3-core, 4-core and 5-core, the most common being 3-core and 4-core.

2-Core Wire

2-core wire is generally flex cable, the same that’s used for appliances only has 2 cores in a cable, a live and a neutral. Mostly used for appliances that are double insulated and do not require an earth.

2-Core and Earth or 3-Core Wire

Probably the most commonly used cable in domestic electrics, 1mm, 1.5mm and 2.5mm 2-core and earth is used for most socket and lighting circuit wiring with 6mm and 10mm 2-core and earth used for heavier cooker and shower circuits.

3-Core and Earth or 4-Core Wire

3-core and earth cable is commonly used in domestic lighting circuits for 2-way lighting e.g. 2 light switches that operate the same light or other situations where switched and permanent lives are needed as well as a neutral.

4-Core and Earth or 5-Core Wire

5-core cable isn’t that commonly used and is found more often than not in SWA or steel armoured cable that’s generally used for underground or outdoor applications. Other than that it’s used in more industrial 3-phase electrical systems where 3 live wires are needed.

What Does 3-Phase Mean?

3-phase electrical wiring is mostly used in industrial situations and it essentially means there are 3 separate electrical supply wires (3 live wires), each slightly out of phase with the other, supplying a given appliance, that requires a constant supply of large amounts of electricity.

Pretty much all domestic electrical supplies are single-phase e.g. there is only 1 single live wire in a cable (along with earth and neutral) that connects to 1 live terminal.

The domestic single-phase electrical supply is AC or alternating current. This essentially means that the voltage supplied over a circuit varies. Sometimes there’s a constant supply and sometimes there’s no supply.

With large industrial machines that suck up loads of electricity, if on a single-phase supply and there is a voltage drop, this can seriously damage a given machine and even cause potential safety issues.

To avoid issues such as this, with a 3-phase supply there is effectively 3 separate live wires supplying electricity and as each is slightly out of phase by a third of a cycle, the electrical supply will always be constant and uninterrupted.

As lower power objects such as TV’s, toasters, kettles, microwaves etc. can easily cope with the fluctuation in AC supply there are no issues such as this on a domestic level.

What are the New UK Wiring Colours?

As it’s essential that the correct wire is connected to the correct terminal, the new UK wiring colours are: Live = Brown, Neutral = Blue and Earth = Green/Yellow or Bare (also Line 2 = Black and Line 3 – Grey for 4-core and earth).

Mixing any of these up and connecting them to the wrong terminal can be catastrophic and potentially deadly, hence the reason we have mentioned this once again!

What Were the Old UK Wire Colours?

Before the wiring colour change that was made official in the UK in 2006, electrical cables were coloured as follows: Live = Red, Neutral = Black and Earth = Green/Yellow or Bare (also Line 2 = Yellow and Line 3 = Blue for 4-core and earth cables).

When connecting into existing circuits that still have the old wiring colours but you will need to use cabling with the new colours, it’s essential to know exactly how to mate the correct wire to it’s old equivalent, hence why we are reiterating the old wire colours once again!

When did UK Wire Colours Change?

The last change in UK wire colours occurred on the 31st of March 2006 and this meant after this date any electrical cables used in new fixed installations had to feature wire colours of brown live and blue neutral.

Although this new rule came into effect on this date, to reduce the volume of old cabling still being used up to the cut off date a rule was brought in that stated that cable with the new colours could be used from the 31st of May 2004.

International Wire and Cable Colours

As we have mentioned, the current wire colours stated above are specific to both the UK and Europe, however if you are visiting our site from a country outside of these areas then it’s important to confirm exactly what wire colours other countries have.

Wiring Colours for the U.S.

In the US there are 2 different types of AC electrical system that can be encountered, a low voltage system (120 – 240 volts) and a high voltage system (277 – 480 volts):

Low Voltage 120 – 240 Volt Wire Colours

The wire colours for US low voltage circuits are. These circuits are commonly found in homes:

• Line/Phase 1 = Black
• Line/Phase 2 = Red
• Line/Phase 3 = Blue
• Neutral = White
• Earth = Green, Green/Yellow or Bare

High Voltage 277 – 480 Wire Colours

The wire colours for higher voltage US circuits are. These circuits are more commonly used in industrial situations:

• Line/Phase 1 = Brown
• Line/Phase 2 = Orange
• Line/Phase 3 = Yellow
• Neutral = Grey
• Earth = Green, Green/Yellow or Bare

Wiring Colours for Canada

The wire colour scheme set by the CEC (Canadian Electric Code) for AC electrical systems in Canada is very similar to the one used in the US and is as follows:

• Line/Phase 1 (single-phase circuits also) = Red
• Line/Phase 2 = Black
• Line/Phase 3 = Blue
• Neutral = White
• Earth = Green, Green/Yellow or Bare

Wiring Colours for Australia

Like the UK, in 2018 Australia also had a change in electrical wire colours, with the old wire colours being: Phase 1 = Red, Phase 2 = White, Phase 3 = Blue, Neutral Black and Earth = Green. After the 2018 wire colour change, the most recent Australian wire colours are:

• Line/Phase 1 (single-phase circuits also) = Brown
• Line/Phase 2 = Black
• Line/Phase 3 = Grey
• Neutral = Blue
• Earth = Green/Yellow

Adding new Colour Wires to Existing Circuits With old Colour Wires

As the new rules regarding wire colour that were introduced in 2006 were only for new installations and not existing then this ultimately leads to the fact that some homes will have cables with both old and new wire colours.

A mixed wire colour installation can be seen in the image below.

You can clearly see that red is connected to the new brown live, black is connected to the new blue neutral and the green and yellow earth stays the same.

All installations where circuits and/or fixed cables have been added and the colours are mixed within the house must carry a warning of such at the fuse board or consumer unit. The warning must be as similar as possible to the one shown below.

Please go to the IET website using the link above for information regarding the new wiring regulations to 3-phase installations or Extensions and alterations to 3-phase installations.

Even if you are not a professional electrician it is absolutely essential that you are aware of the change in wire colour that occurred in 2006 and the fact that it’s possible to have both old and new wire colours in the same property.