A guide to british electrical wiring colours

cable coloursBefore we start talking about the meaning of each one of the electrical cable colours in the UK, we must understand a bit about electricity in general and about the British wiring colours as they are now and as they were before 2006.

In 2006, the 17th Edition, amendment 2 of the BS7671 Wiring Regulations sought to harmonise the house wiring colours then in use in the UK with those already in use on the European mainland. This was to ensure consistency, avoid confusion and allow trade of electrical goods as well as compatibility of electrician’s qualifications between the mainland and the UK.

What if my house has old wiring?

You hear a lot of talk about it being imperative that the old wiring must be ripped out and replaced. The practice is known as rewiring a house. While it is important that the wiring is checked by a qualified electrician, there is no compulsion to have the old wiring replaced as long as it is still in good condition, and an electrician will be able to tell you whether this is the case. In the average house, there are what are called ‘ring mains’ and ‘spurs’, both names for different kinds of wiring circuits. The electrician will check the old wiring and find one of three situations:

  1. All circuits are safe.
  2. Some circuits are safe and others need to be replaced.
  3. All circuits need to be replaced.

If the electrician finds that some circuits are safe and some are unsafe, you may be advised to have all circuits replaced because if some have deteriorated, then it won’t be long before all the rest start deteriorating. This is a perfectly acceptable practice by the electrician and it will probably cost you less in the long term to have everything done together rather than on two separate occasions.

Why different wiring colours exist (safety first!)

In theory, electricity will travel along one wire to reach an appliance. If you can imagine that the ‘one wire’ has been cut in half and the appliance fitted between the two cuts. What you have now is one wire bringing electricity to the appliance and one wire completing the circuit by taking electricity away from the appliance, these wires are called ‘live’ and ‘neutral’ respectively. That accounts for two wires, what about the third? The third wire present in household wiring cables is known as the ‘earth’ wire and it is there as an important safety consideration. Electricity will always take the easiest route (the route of least resistance) to the earth. If there is a fault with the live or neutral wires which makes any exposed metal also ‘live’, then people run the risk of being electrocuted as the electricity tries to run to earth through their body.  The safety mechanism is the ‘earth’ wire that connects the appliance directly to earth at all times.

In the UK it isn’t only household wiring that has three wires, inside appliance plugs, there will always be three wires of different colours as well (Some appliances only need two wires. These are called double earthed appliances and are a special case without a separate earth wire). This allows for consistency when working on appliances with their plug wire colours being the same as the electrical wiring colours for lights and sockets as well as their corresponding circuits or ring mains.

Old UK wire colours – Changes since 1977

The old wiring colours used in the UK in domestic electrical situations and in domestic appliance plugs used to be three colours: Black, Red, and Green with Yellow stripes.

  • Black. The black electrical wire used to be the colour for the neutral wire.
  • Red. The live wire colour used to be red.
  • Green & Yellow. The earth wire colour used to be pure green before 1977, then changed to green and yellow and has been the same ever since.

New wiring colours – since 2006

In 2006, the old electrical wiring colours were finally phased out. Although old wiring from before 2006 still exists in some houses and old appliances, as long as the wiring is in good condition it can still be used safely. Although old wiring may look safe to the unaided eye, you must have the wiring properly checked by a qualified electrician before you know definitely whether it is safe.

The modern wiring installed since 2006 saw a change in the colour coding of electrical wiring. What used to be red and black wires for the live cable colour and neutral cable respectively changed to blue and brown wires for neutral and live cables.

Plug Wire Colours

plug wiring colours
Image from p3connectors.com

To summarise the latest changes:

  • The blue colour coded wire denoting the neutral cable changed from black to blue.
  • The brown electrical wire now denotes the live wire and changed from red to brown.
  • Green & Yellow. This has not changed and still denotes the earth wire.

Earth cable colour change

Remember that the earth green wire changed to a green and yellow electrical wire in 1977 and hasn’t changed since. This was the first wire colour code to be changed because it is the safety wire and no-one wanted to be confused with that one so they harmonised that one first.

Cable & Wire Conditions

The condition of electrical wiring in a domestic situation is one of the most important things to check when buying a second-hand home or renovating your current one. Remember that as a homeowner you have a responsibility to your family and to yourself to regularly visually check the state of the electrical circuits within your house.

The first check is to notice if there are any black burn marks around wall power point sockets or light switches. If there are then the switch might be starting to wear out and causing sparks when operated. Similarly, if you smell a burning odour like the smell of burning plastic or rubber then the wire insulation may be breaking down causing short-circuiting or other problems.  The last thing you check is not easy to look at unless you are happy and confident with what you are doing as it involves removing the plastic cover plates from the power point sockets and light switches to look at the wiring behind the covers. Remember that if you find you are looking at black and red colour coded wires you have old wiring that may or may not be deteriorating. If you see the old coloured insulation crumbling, cracking or splitting then you definitely need to call in an electrician, however, they might look ok. If they do then you will still need to call in an electrician to check the cables using his or her specialist equipment to determine their condition. Don’t forget too that you are only looking at a few centimetres of wiring behind the cover plates whereas there are literally hundreds of metres of electrical wiring hidden behind the walls, under floors and above ceilings that you will never see. Only an electrician can monitor those. Remember that the average lifespan of electrical cable insulation is about 30 or 40 years old so if you see the old type of cable installed, it is better to play safe than be sorry.

Another thing that you may not be aware of is the problem with using extension leads in a house. Up until about the 1990s, most rooms in a house just had one or maybe two power points installed. In a living room, the only appliances were usually a television and a table lamp. In a kitchen, the only common appliances were a kettle and toaster. In bedrooms there used to be usually just one socket for a table lamp. These days there just aren’t enough power points in a room to satisfy our electrical needs so in an older house we use extension leads to increase the number of power points available. The average living room will probably need sockets for television, satellite video box, wifi router, CD player, DVD player, telephone charging dock as well as two or three table lamps. The average bedroom needs electrical outlets for television, personal computer, printer, monitor, video game box, table lamp, charging points for smartphone and tablet. All these appliances are plugged into an extension lead which in turn is plugged into a socket designed to cope with one appliance. When everything is turned on at the same time, these appliances are drawing current for which an old ring main was just not designed. The wire becomes hot because of the additional current which causes additional strain on the ancient insulation, eventually, something catches on fire and you have a typical household electrical fire. Modern wiring, circuit breakers instead of fuse boxes and fitting enough additional sockets in each room when the rewiring job is being done will help prevent any problems with electricity in your home.

Safety Considerations

So far we haven’t said too much about safety, so let’s just take a few minutes to list some items you should think about before doing any of the work suggested in this article.

You must remember that electricity is very dangerous in the wrong hands. And the wrong hands are always ours. If you are not sure about how to do anything at all, you should not attempt it. Instead, contact a qualified electrician who will be more than happy to come and take a look safely.

If however, you feel confident and competent enough to check things and that includes something as basic as changing a plug on an appliance, there are a few simple but effective rules you should observe before doing anything.

  • If you see sparks, black smuts or smell burning coming from any light switches or power points, make sure they are turned off at the wall and if possible at the fuse box or circuit breaker. Then call an electrician.
  • If you decide to remove the protective cover from a light switch or power point, turn the switches off and isolate the circuit at the fuse box or circuit breaker.
  • If you decide to rewire an electrical plug or take the back off an electrical appliance, ensure the appliance is turned off and the plug is removed from the socket.
  • If you are rewiring an electrical plug, ensure the correct colour coded wires are in the correct positions. In the UK if you look at the brass pegs on a standard 3 pin electrical plug, there are two rectangular brass pegs orientated at right angles to the plug (live and neutral) and one rectangular brass peg orientated in line with the plug  (earth). The brown coloured live wire connects to the brass terminal at one end of the fuse; the green and yellow earth wire is connected to the middle brass terminal, and the blue coloured neutral wire is connected to the other brass terminal. If you aren’t sure then seek advice from a professional.

Conclusion

By now you probably know a bit more about domestic electrical wiring than you did yesterday. You now know that the brown electrical cable is the modern live cable colour, whereas the old colour code was red. Similarly, if the cables in your appliance plug are modern colour coded then you know they should be ok to use. If you have a red coloured cable anywhere then ask an electrician to look at it for you to check the condition of the wiring.

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