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Cable Types

Just as you would expect, there is a multitude of cable types available. For domestic work, however, we need only concern ourselves with a few.

Single core cable

Single core stranded cable

Single core cable is mostly used for industrial applications where it is run in conduits.

In domestic wiring it is usually only used for certain situations. Here they consist of stranded conductors twisted together and housed in a PVC covering. The reason they are manufactured with stranded conductors rather than a solid core is to allow them to be bent easily. A solid core of comparable diameter would be very difficult to work with.

For example, 6 mm sq. single core, colour coded green and yellow, is used for earthing and supplementary bonding. 10mm sq (minimum) single core colour coded green and yellow is used for the main bonding conductors between the earth terminal block in the consumer unit and incoming metal water, gas and oil service pipes. 16 mm sq. single core colour coded green and yellow is used for connecting the earth terminal on the consumer unit to the Company’s earth connection. 16 mm sq. single core which is insulated and sheathed, colour coded brown (old cable colour = red) for live or blue (old cable colour = black) for neutral, is used for the connection of the consumer unit to the meter.

Two core and earth cable

Twin and earth cable

Often referred to as ‘twin and earth’ these may have solid conductors or separate strands twisted together to provide flexibility for larger cables. The live and neutral are colour code insulated. The earth is not insulated. All three are then sheathed in a protective layer.

Insulating bare earth with green and yellow sleeving

Insulation must be provided for the earth conductor when it is exposed to make connections. This is done using green and yellow sleeving available from merchants.

Three core and earth cable

Three core and earth cable

This is similar to two core, but has three conductors, colour coded brown, grey and black (old cable colours = red, yellow, blue) as well as an earth. It is used where two way lighting is needed. It provides the necessary additional conductor between the two switches operating the same light fitting. These colours are for identification purposes only as any, or all, may be live depending on how the circuit is wired.

Green and yellow sleeving to insulate the earth

As with the twin and earth cable, insulation must be provided for the earth conductor when it is exposed to make connections. This is done using green and yellow sleeving available from merchants.

Electics Safety warning

box alertThis material is for information purposes only. Strict rules govern what electrical work can be done without notification and inspection.
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