Electrical Wiring Colours Explained

Changes to wiring colour codes ensure consistency across fixed electrical and mains-powered cables. The blue wire, serving as the neutral wire, directs electricity away from the appliance, while the brown wire, acting as the live wire, supplies electricity to the appliance. These wires form a circuit, and properties with older wiring should be regularly inspected by an electrician to ensure safety.

The green and yellow wire, known as the earth wire, plays a crucial safety role by providing a path for electricity to safely flow to the earth. This prevents the risk of electrocution by directing electricity away from the human body. Warning signage should indicate installations with mixed-colour circuits and fixed cables, prominently displayed on the fuse board or consumer unit.

The electrician should attach appropriately-coloured sleeving to the different wires to enable easy identification of the corresponding wiring. As previously mentioned, the old-style black neutral wiring has been replaced with blue. Similarly, red live wiring is now brown.There are varieties ofcables with similar colouring to the mains wiring. As an example, TV aerial cables don’t carry any voltage but do have the same brown colour as the live mains cabling. It is also common to find black cabling trailing behind the TV. This is the same colour as the old neutral wire. However, if there is any doubt, you should arrange for a professional electrician to carry out an inspection to ensure safety.

Single and Three-Phase Wiring

It’s also important to be aware of the difference between single and three-phase wiring.

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Single-phase wiring
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Three-phase wiring
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Has two wires: one live (black or red) and one neutral (blue)
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Has three or four wires: three live (black, red, brown or grey) and one neutral (blue)
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Has a voltage of 230V between the live and neutral wires
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Has a voltage of 400V between any two live wires
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Good for balancing electrical loads on the network
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Good for powering electrical machines and equipment
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You can identify either the two or three-phase connection by counting the wires connected to the electrical service panel. In addition, you must not make the mistake of confusing the natural blue and green/yellow earth connection when referring to the electrical system.

As of 1 July 2009, Hong Kong mandates the use of a newwiring colour code in all new fixed electrical installations. The updated scheme replaces the old colour code with significant changes in identifying phase and neutral conductors.

In the old system, blue represented phase conductors, while black signified neutral conductors. Conversely, in the new code, blue is designated for neutral conductors, and black identifies phase conductors.

This reversal may confuse electrical workers and potentially lead to accidents if not addressed properly. Mixing old and new colour schemes within the same installation poses a risk of electrical mishaps if workers overlook the transition. To mitigate such risks, it is crucial to ensure that all electrical workers are fully aware of the change and have undergone appropriate training before engaging in any wiring tasks.

The newwire colour code applies to new fixed electrical installations in Hong Kong, such as domestic, commercial, and industrial premises. Ultimately, it aims to enhance electrical safety and avoid confusion with other wire colour codes used in different countries and regions.

Examples of Wiring Colour Code Applications in Hong Kong

To help you understand how the wiring colour code applies to different situations and scenarios, here are some examples of wiring colour code applications in Hong Kong:

• Lighting, outlets, or switches usually follow the general wiring colour code for Hong Kong, which is brown for live, blue for neutral, and green/yellow for earth. However, some lighting fixtures may have only two wires without an earth wire, and some outlets or switches may have an extra wire for power indication or control.
• Exterior wiring may use the same or different colours as the internal wiring, depending on the system type and design. However, exterior wiring needs additional safety and protection measures, such as weatherproofing and insulation. It is recommended to consult a qualified electrician or manufacturer before installing or repairing any outdoor wiring.
• Special wiring may have different colour codes from the general wiring, depending on the system specifications and standards. For example, telecommunication, data, or audio-visual systems may use different colours for different functions or signals. It is important to refer to the system manuals or labels before connecting or disconnecting any special wiring.

Electrical wiring can be dangerous if not done properly or safely, as it can cause fire, shock, or injury. Therefore, it is important to follow some basic safety tips when working with electrical wiring.

• Always turn off the power supply and use a voltage tester or a multimeter to check if the wires are live or not.
• Wear protective gloves, goggles, and shoes, and avoid touching bare wires or energised metal parts.
• Keep flammable materials and liquids away from electrical wiring or equipment, and follow the manufacturer’s instructions and local wiring colour codes to ensure safety.
• Hire a qualified electrician to replace, repair, or install electrical wiring or equipment, as doing it yourself can be illegal or risky.
• Contact a qualified electrician or emergency services if you see exposed or damaged wiring, or notice sparks, smoke, or flames coming from the wiring.
• Do not connect wires of the wrong colour, as this can lead to serious issues such as short circuits, overloading, overheating, or electrocution. Adhere to the wiring colour codes in Hong Kong and verify wire polarity before connection.