Designing homes to conserve energy and use it efficiently, from sources that cause least environmental harm.

Wiring materials

Wiring materials must comply with the relevant standards and should have supplier declarations of conformity (SDoCs) available where required.

Cable Insulation colour
Two-core plus earth TPS (tough plastic sheathed)

Two-core cable (no earth)
Phase – red
Neutral – light blue or black
Earth – green or green/yellow
(Note that older TPS cable may have no insulation to the earth wire.)
Lighting wiring Phase – brown
Neutral – black
Earth – green/yellow (where provided)

Two-core plus earth cable must be used for power outlets. It is also recommended for lighting circuits so that, if a metal light fitting is installed, it has earth protection.

TPS two-core
cable (mm2)
Earth Current
Used for:
6.0 Yes 40 9.75 • Dedicated circuit to freestanding stove.
4.0 Yes 32 7.75 • Dedicated circuits to hob, wall oven, heat pump, embedded floor and undertile heating, remote electric continuous-flow water heater.
2.5 Yes 24 5.75 • Power outlets with maximum 3 double outlets per circuit – kitchens, laundries.
• Power outlets with up to 12 double outlets per circuit and maximum load of 10 amps per outlet – areas other than kitchens, laundries.
• Water heater with maximum element rating of 3–4 kW.
• Submains to garage or outbuilding (separate circuit for each building).
• Permanently connected appliances. (Note that appliances rated above 10 amps require a dedicated circuit, but up to 10 amps may be wired as part of power outlet circuit.)
1.5 Yes 18 4.25 • Water heater with maximum element rating of 3 kW.
1.0 Yes 14 3.25 • Lights with maximum load on any one circuit of 10 amps. (Note that a minimum of 2 circuits per dwelling is required.)

Updated: 16 November 2016