This means that, if the live or neutral wires develop a fault causing any exposed metal to become live, there is a risk of electrocution as electricity can attempt to find its way to earth via the human body. In addition to household wiring, all plugs in the UK feature the three colours of wire we mention above. The primary purpose for doing this is to make the wiring consistent across appliances and the electrical wiring used in sockets and lights including their corresponding circuits and mains.
Prior to , different colours of cables were used in UK domestic electrical wiring and appliances for the neutral and live wires. The old colours were:. The old electrical colours were phased out in but, as you can imagine, old wiring still exists in many houses and appliances. If your home has old wiring, it is worth getting it checked by a qualified electrician to make sure it is in safe working order. It is not always necessary to rewire your house by replacing old wiring providing your existing wiring is properly inspected.
UK homes contain two types of wiring circuits known as ring mains and spurs. When inspecting your property, an electrician will check to see whether or not your circuits are safe and whether one or more of them need to be replaced. This is because, if they were installed at the same time, the likelihood is that any circuits currently working will likely also fail at some point in the near future.
There are some tell-tale signs that the wiring in your house may need replacing, including:. Electricity can be extremely dangerous — and potentially lethal — if not handled in the correct manner. Insulation and sheathing can deteriorate with age, but also with excessive temperatures and overloading, as well as the rubber deteriorating if it has been exposed to direct sunlight.
When cables deteriorate, it means they lose their insulation and flexibility, becoming dry and more like to crumble away and break. Pres saw lead-sheathed cables see above being used more in domestic dwellings. They are rubber insulated, copper conductors, with an outer sheath of lead. Just like TRS cables, lead sheathed cables deteriorate over time as they are rubber insulated.
Lead sheathing is still used in some older properties and could be gradually deteriorating without you knowing. If you spot any lead sheathed cables, please be warned that these cables are past their expected working life and should be inspected by an electrician immediately for safety.
PVC-insulated sheathing became popular from s onwards, and it is now the most common form of sheathing. However, you can still find TRS and lead sheathed cables in period properties today. Make sure your home is safe and using sheathing that will not deteriorate over time. The old wiring colours in the UK still have three wires: earth, live, and neutral.
The new wiring colours became mandatory in , although they had been in use since As of the 1st April , the government changed the legislation outlined in BS Requirements for Electrical Installations to make it illegal to use the old wiring colours in new installations.
Some properties have both old and new electrical wiring systems. Any extensions built after will feature the new wiring colours, but the rest of the house may still have the older colours. In situations where both wiring systems are present, remember that:.
Find out how you could train as a domestic gas engineer by downloading a free copy of our information pack. Single-phase is by far the most common system and is used in most homes, whereas three-phase supplies can cope with large amounts of power so are used in industrial buildings.
Three-phase systems have three separate live wires — the power in each live wire is out of phase with the other two, hence the term three-phase. On the other hand, three-phase systems can be thought of as three AC supplies working together with their sine waves out of phase, so power is always being supplied. We need three-phase systems for industrial usage so that there is always power being supplied — without this constant supply of power, heavy machinery would not be able to function properly.
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