Twin & Earth Cable

Twin and earth (6242Y) is the standard flat cable for fixed wiring inside homes and many commercial buildings. It is used for lighting circuits, socket circuits and dedicated circuits such as cookers, electric showers and immersion heaters, as well as for wiring smoke alarms and thermostats.

Twin and earth sizes refer to the cross-sectional area of each copper conductor in square millimetres (mm²), for example 1.5mm², 2.5mm² or 6mm². The bare earth conductor (CPC) is smaller than the live and neutral – 2.5mm² twin and earth has a 1.5mm² earth, and 1.5mm² has a 1.0mm² earth. The cable is sold by length, such as 100m coils.

In typical UK and Irish homes, 1.0mm² or 1.5mm² twin and earth is used for lighting circuits, 2.5mm² for ring final socket circuits, and 4mm², 6mm² or 10mm² for higher loads such as cookers and electric showers. The correct size always depends on the load, cable length, installation method and protective device, and must be confirmed by a qualified electrician to BS 7671.

No, the Twin and Earth cable is not suitable for external usage. The reason is because the exterior sheath material is prone to UV assaults therefore, the cable must not be in direct contact with sunlight.

Our range of Twin and Earth cables are available in the following sizes:

• 1.5mm Twin and Earth Cable
• 2.5mm Twin and Earth Cable 
• 6mm Twin and Earth Cable 
• 10mm Twin and Earth Cable 
• 16mm Twin and Earth Cable 

Twin and earth cable has two insulated copper conductors – brown for line and blue for neutral – plus a bare copper earth conductor (CPC), all inside an outer sheath. Standard 6242Y cable has a grey or white PVC sheath, while 6242B low smoke zero halogen (LSZH) versions give off less smoke and toxic fumes in a fire. The bare earth should be sleeved green/yellow wherever it is terminated.

Flat twin and earth (often called FTE or T&E) is the flat-profile version of 6242Y cable, with the line and neutral insulated and the earth bare between them. It is designed for indoor fixed wiring – clipped direct, in conduit or trunking, or buried in plaster – and is not suitable for outdoor use, as UV light degrades the sheath. Meteor stocks it in common sizes including 1.5mm², 2.5mm², 6mm² and 10mm².

As well as standard PVC twin and earth (6242Y), we stock low smoke zero halogen (LSZH, also called LSOH or OHLS) twin and earth (6242B). LSZH cable gives off far less smoke and toxic gas in a fire, so it is often specified for escape routes, public buildings and other places where smoke could put people at risk.

Twin and earth is normally terminated into back boxes, consumer units and accessories through rubber grommets or the knockouts of the box, rather than with glands. Glands are mainly used with flexible cords and SWA armoured cable. Wherever a twin and earth cable enters an enclosure, use a suitable grommet or gland so the sheath is protected from sharp edges.

On average, twin earth cables are meant to last around 25 years. However, if the t&e cable is well-installed and has only dealt with lightly loaded systems, then it can easily last up to 50 years. 

The risk factors that can reduce twin and earth cable life include damp conditions, UV light, hot conditions, running the cable fully loaded for long periods of time, and frequent changes of accessories.

6242Y is standard twin and earth with a PVC sheath and a bare earth conductor. LSF versions, such as 6193B, use a low smoke and fume sheath, and many have an insulated earth. LSF cable is often specified for public buildings and escape routes because it gives off less smoke and harmful gas in a fire.

Brown/brown twin and earth has both insulated cores coloured brown. It is used for switch drops and switched lighting where both conductors are line conductors, so no blue core needs to be re-marked. It saves time and helps avoid confusion when the circuit is tested or altered later.

In many twin and earth sizes, the protective earth conductor is reduced, for example 1.0mm in 1.5mm cable and 1.5mm in 2.5mm cable. This is allowed because the earth only carries fault current briefly. The circuit design must still confirm earth fault loop impedance and protective conductor adequacy under current wiring regulations.