3 Core and Earth

3 core and earth cable is a fixed-wiring cable with three insulated conductors plus a circuit protective conductor, used where a circuit needs an extra switched or permanent line alongside the neutral. Typical jobs include two-way lighting, fan isolator feeds and heating controls. Our range covers PVC/PVC 3 core and earth in 1.0mm and 1.5mm on 100m coils, plus 2.5mm three-core blue Arctic flex on a 100m drum.

Open a trade account for trade pricing, and order in-stock coils before 5pm for next working day delivery anywhere in Northern Ireland or the Republic of Ireland.

3183Y 2.5B In-Stock

2.5mm² 3 Core Arctic Flex Blue 100m Drum

£176.28 inc. VAT

PVC/PVC 1.5mm 3 Core and Earth Cable (100m coil) 1.5 cable 100m with Meteor Electrical

6243Y 1.5/EU In-Stock

PVC/PVC 1.5mm 3 Core & Earth Cable (100m coil)

£135.92 inc. VAT

6243Y 1.0/EU In-Stock

PVC/PVC 1.0mm 3 Core & Earth Cable (100m coil)

£101.42 inc. VAT

How to choose the right 3 core and earth cable

Three core and earth is the workhorse for any circuit that needs more than a simple line and neutral. The third core carries a strapper, a switched line or a permanent feed, so getting the size and construction right at the start saves rework later.

Where it is typically used

Two-way and intermediate lighting – running strappers between switch positions.
Extractor fans with run-on timers – a permanent line, a switched line from the light, and a neutral.
Central heating wiring – feeds between programmers, thermostats and valves.
Outside lighting with PIR override – where a separate switched feed is needed.

Size and construction

1.0mm and 1.5mm cover most lighting and control circuits, but the correct size always depends on the design current, the length of run and the installation method, so check current wiring regulations (BS 7671) and the cable manufacturer's ratings before you buy. PVC/PVC flat cable is meant for fixed wiring inside buildings; if the run is exposed to weather or mechanical damage, look at our SWA armoured cable instead. The 2.5mm Arctic flex listed here is a flexible cable, intended for portable or temporary connections rather than buried fixed wiring.

Identifying the cores

Current three-core cable uses brown, black and grey for the line conductors, with a bare protective conductor that should be sleeved green/yellow at every termination. Where a core is used as a switched line or strapper, mark it clearly at both ends so the next person working on the circuit can follow it. Terminate neatly using suitable pushwire and lever connectors in an accessible enclosure.

If you only need a single line and neutral, standard twin and earth cable is the simpler choice.

Buying from Meteor Electrical

We are a family-run wholesaler with over 40 years in the trade, stocking 5,000+ lines from our Cookstown warehouse. Orders over £30 / €35 ex VAT ship free, and you can also collect from the Cookstown trade counter. Need advice on a cable? Call 028 8675 1515 (048 from ROI), Monday to Friday, 8am–5pm.

FAQ's Ask Your Own Question

What is 3 Core and Earth Cable?: 3 Core and Earth Cable is used to wire two-way light switches since it has three cores and an earth conductor. The cable has four cores, one of which is neutral and the other three of which might be live depending on how the lighting circuit is wired and where the switches are located. To facilitate identification, each of the cores (save the earth) is covered in a layer of color-coded PVC insulation, which is then wrapped in an outer layer of PVC known as the sheath.
Where can 3 Core and Earth Cable be used?: The 3 Core and Earth cable is commonly used in domestic environments. The three-core cable is used for lighting circuits and circuit installations.
What are the 3 core and earth wiring colours?: The 3 core and earth wiring colours are live brown wire, a neutral grey wire, a green/yellow protective earth wire, and an additional black conductor.
What colour is neutral in 3 Core and Earth cables?: The neutral wire of the 3 core and earth cable is grey.
What is the difference between 3 core and 4 core?: 2 core cable does not include an earthing wire and can be used with any electrical object that has a non-conductive outside surface.

Any light, lamp, bulb holder, or fitting with a conductive or metal outside surface must be wired with 3 core cable to avoid electrocution or serious damage.
What size 3 core and earth do I need for two-way lighting?: For most domestic two-way lighting circuits, 1.0mm or 1.5mm 3 core and earth is used, matched to the size of the rest of the lighting circuit. The final choice depends on the protective device rating, run length and installation method, so confirm it against current wiring regulations and the manufacturer's current-carrying data before installing.
Can I use 3 core and earth instead of twin and earth for a fan isolator?: Yes, 3 core and earth is the usual choice for a fan fitted with a timer or humidistat. It carries the permanent line, the switched line from the lighting circuit and the neutral to a three-pole isolator. Check the fan manufacturer's wiring diagram, as some models need a different arrangement or a dedicated supply.
Should the bare earth in 3 core and earth cable be sleeved?: Yes. The bare circuit protective conductor should be covered with green/yellow sleeving wherever the sheath is stripped back at a termination. This identifies it as the earth and stops it touching live terminals. Sleeving is cheap and quick to fit, and inspectors will look for it when the installation is tested.