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Best Electrical Cable for Home Wiring: UK Types, Sizes and Colours
Updated October 2026 · Meteor Electrical guides · 10 min read
Quick answer: For most UK homes, the best electrical cable for fixed wiring is PVC twin and earth (6242Y). Typical sizes are 1.0 or 1.5 mm² for lighting, 2.5 mm² for sockets, and 6 or 10 mm² for cookers and showers. Use 3 core and earth for two-way lighting, SWA armoured cable underground or outdoors, and flex for appliances. Final sizes must come from BS 7671 circuit design.
Choosing the best electrical cable for home wiring comes down to three questions: what the circuit supplies, where the cable runs and how it is protected. This guide gives typical cable sizes by circuit, explains when to use each cable type, and shows the UK colour codes old and new. You can browse our full range of electrical cables as you read.
In this guide
- Which cable is used for house wiring in the UK?
- What size twin and earth cable do you need for each circuit?
- What are the main types of electrical cable for homes?
- LSZH vs LSF vs PVC: which insulation should you choose?
- What are the UK cable colours, old and new?
- How do you choose the right cable for a job?
- Which regulations apply to home wiring cable?
- FAQs
Which cable is used for house wiring in the UK?
The fixed wiring in most UK and Irish homes is flat twin and earth cable, often called T&E or by its code 6242Y. It has two insulated cores, live (brown) and neutral (blue), plus a bare copper circuit protective conductor (earth) inside a grey or white PVC sheath.
T&E runs from the consumer unit to the lights, sockets and fixed appliances. Where it is not suitable, other cables take over: 3 core and earth for multi-way lighting, SWA for buried or outdoor runs, flex for appliances, single-core cable in conduit, and fire-resistant cable for life-safety systems.
What size twin and earth cable do you need for each circuit?
Cable size is the cross-sectional area of each conductor in square millimetres (mm²). A bigger cable carries more current and has less voltage drop over a long run. The table shows typical sizes found in UK homes, not a substitute for design.
| Circuit | Typical cable | Typical MCB / RCBO |
|---|---|---|
| Lighting | 1.0 mm² or 1.5 mm² twin and earth | 6 A |
| Mains smoke alarms (typical house) | 1.0 mm² or 1.5 mm² twin and earth | 6 A, often on a lighting circuit or its own circuit |
| Immersion heater | 2.5 mm² twin and earth, with heat-resistant flex for the final connection | 16 A |
| Radial socket circuit | 2.5 mm² twin and earth | 20 A |
| Ring final socket circuit | 2.5 mm² twin and earth | 32 A |
| Larger radial socket circuit | 4 mm² twin and earth | 32 A |
| Cooker or oven | 6 mm² twin and earth (10 mm² for larger cookers) | 32 A to 40 A |
| Electric shower | 10 mm² twin and earth for most 8.5–10.5 kW showers (6 mm² for smaller showers on short runs) | 40 A to 50 A |
| 7 kW EV charger | 6 mm² or larger, often SWA | 32 A |
| Garage, shed or garden office | SWA armoured cable, sized for the load and run length | Set by design |
The figures above are common starting points only. BS 7671 requires the designer to check the protective device, the installation method (for example clipped direct, in a stud wall or buried in loft insulation), grouping with other cables, ambient temperature, voltage drop and earth fault loop impedance. A long run or cable surrounded by insulation can need the next size up. Shop twin and earth cable.
Why is the earth smaller than the live and neutral?
In 6242Y the bare earth is reduced in size, for example 1.5 mm² in 2.5 mm² cable and 2.5 mm² in 6 mm² cable. That is allowed because the earth only carries current briefly during a fault. Where it is exposed at accessories it must be sleeved green/yellow.
| Twin and earth size | Earth (CPC) size |
|---|---|
| 1.0 mm² | 1.0 mm² |
| 1.5 mm² | 1.0 mm² |
| 2.5 mm² | 1.5 mm² |
| 4 mm² | 1.5 mm² |
| 6 mm² | 2.5 mm² |
| 10 mm² | 4 mm² |
| 16 mm² | 6 mm² |
Pro tip: Cable buried in or covered by loft insulation can lose around half of its current-carrying capacity. Route cables above the insulation or clip them to the side of joists, and tell your designer if a run cannot avoid it.
Planning a full house rewire? Our guide to the best twin and earth cable for a house rewire covers sizes by circuit, voltage drop and 6242Y vs 6242B LSZH in more detail.
What are the main types of electrical cable for homes?
| Cable type | Best for | Not for |
|---|---|---|
| Twin and earth (6242Y) | Lighting, sockets, cookers, showers and other fixed indoor circuits | Burial, outdoor runs or connecting appliances |
| 3 core and earth (6243Y) | Two-way and intermediate lighting, fan isolators, some heating controls | General socket circuits |
| SWA armoured | Buried runs, outbuildings, EV chargers, outdoor walls | Short indoor runs where T&E will do |
| Flex | Appliances, pendants, portable equipment | Fixed wiring in walls or ceilings |
| Single-core (6491X) | Conduit and trunking, earthing and bonding | Clipping direct without a sheath or enclosure |
| Fire-resistant | Fire alarm and emergency lighting systems | Ordinary power and lighting circuits (not needed) |
3 core and earth cable (6243Y)
3 core and earth has three insulated cores coloured brown, black and grey, plus a bare earth. Note there is no blue core. It is mainly used for two-way and intermediate switching, where a light is controlled from two or more places such as the top and bottom of the stairs. It also suits fan isolators and some heating controls that need a switched live. Because the black and grey cores are often used as switched lives or "strappers", mark them with brown sleeving so the next person knows they can be live. Browse 3 core and earth cable.
SWA armoured cable
Steel wire armoured (SWA) cable has a layer of galvanised steel wires under a tough outer sheath, which protects it from spades, impact and rodents. It is the usual choice for buried supplies to garages, garden offices, outdoor lighting and EV chargers, and for external runs on walls. Common versions are 2, 3 and 4 core with XLPE insulation (BS 5467), terminated with proper glands so the armour is earthed.
There is no single burial depth set in BS 7671, but the cable must be deep enough to avoid damage, with warning tape above it. Sizing depends heavily on run length because of voltage drop, so have the circuit designed first. See our SWA armoured cable.
Flexible cable (flex)
Flex has stranded conductors so it can bend repeatedly without breaking. Use it from a fused connection unit or plug to an appliance, and for pendant lights, never for fixed wiring inside walls. Common types include:
- 3 core PVC flex (3183Y): brown, blue and green/yellow, for most appliances.
- 2 core flex (2182Y): for double-insulated items with no earth.
- Heat-resistant flex (3093Y): for immersion heaters, storage heaters and other hot locations.
- Rubber flex (H07RN-F): for outdoor, workshop and site use where the cable is dragged or gets wet.
Browse our flexible cables.
Single-core cable and earthing conductors
Single-core cables (6491X) are drawn into conduit or trunking, for example in garages, workshops and commercial jobs. Green/yellow singles are used for the main earthing conductor and protective bonding to gas and water pipes. In many homes these are 16 mm² and 10 mm² respectively, but the right size depends on the supply type and must be confirmed by the electrician. See single-core cable.
Fire-resistant cable
Fire-resistant cable is designed to keep working for a set time in a fire, so alarms and emergency lights stay on while people escape. It is needed for fire detection and alarm systems designed to BS 5839 and emergency lighting to BS 5266. In a typical house, mains smoke alarms with battery backup can often be wired in ordinary twin and earth, but larger homes, HMOs and flats may need a higher grade system with fire-resistant cable. Check the system design before you buy. Browse fire-resistant cable.
LSZH vs LSF vs PVC: which insulation should you choose?
Standard PVC cable is fine for most domestic wiring. The difference shows up in a fire, when burning PVC gives off thick smoke and corrosive hydrogen chloride gas.
- PVC (6242Y): the everyday choice for homes. Cheapest and easy to work with.
- LSF (low smoke and fume): a modified PVC that produces less smoke, but it still contains halogens.
- LSZH or LS0H (low smoke zero halogen): gives off little smoke and no halogen gases. Often specified for escape routes, public buildings, tunnels and enclosed spaces where people need to get out.
For a normal house, PVC twin and earth is usually all you need unless the specification calls for LSZH. Whatever the type, BS 7671 requires cables to be supported so they will not collapse early in a fire, for example with metal clips or fixings rather than relying on plastic alone.
What are the UK cable colours, old and new?
UK wiring colours were harmonised with the rest of Europe from 31 March 2004, and the old colours were phased out by 2006. Homes wired before then often have a mix of both, so never assume what a core does from its colour alone.
| Conductor | Current colour (since 2004) | Old colour (before 2004–2006) |
|---|---|---|
| Live (line), single-phase | Brown | Red |
| Neutral | Blue | Black |
| Earth (protective conductor) | Green/yellow | Green/yellow (plain green in very old installations) |
| 3 core and earth cable | Brown, black, grey | Red, yellow, blue |
| Three-phase lines L1, L2, L3 | Brown, black, grey | Red, yellow, blue |
| Appliance flex | Brown, blue, green/yellow | Brown, blue, green/yellow (unchanged since the 1970s) |
Safety: Black meant neutral in the old colours but is a live core in new 3 core and three-phase cable. Where old and new colours meet, BS 7671 requires a warning notice at the consumer unit. Always prove a circuit dead with an approved voltage tester before touching any conductor.
How do you choose the right cable for a job?
Work through these steps in order, whether you are buying for a single circuit or a full rewire:
- Define the circuit. What does it supply, what is the load in amps and what protective device (MCB or RCBO) will protect it?
- Pick the cable type. T&E for most indoor fixed wiring, 3 core and earth for multi-way switching, SWA for buried or exposed outdoor runs, flex for appliances.
- Check the route. Note insulation, grouping with other cables, heat sources and outdoor exposure, as all of these reduce the current a cable can carry.
- Size it. Start from the typical size, then check current capacity, voltage drop over the run length and earth fault loop impedance against BS 7671.
- Choose the insulation. PVC for most homes, LSZH where specified, fire-resistant for life-safety systems.
- Buy approved cable. Look for BASEC approval or the HAR mark on the sheath, and buy enough to avoid joints.
Which regulations apply to home wiring cable?
BS 7671, the IET Wiring Regulations, sets the rules for designing, installing, inspecting and testing wiring in the UK. In the Republic of Ireland the equivalent is I.S. 10101. Both cover cable selection, safe zones in walls, RCD protection for cables buried in walls and support of cables.
In England and Wales, much domestic electrical work, such as a new circuit, a consumer unit change or work in a bathroom, is notifiable under Part P of the Building Regulations. Northern Ireland, Scotland and the Republic of Ireland have their own rules. A registered electrician can self-certify the work and issue an Electrical Installation Certificate.
Credit: eFIXX
Key takeaways
- Twin and earth (6242Y) is the standard cable for fixed wiring in UK homes.
- Typical sizes: 1.0 or 1.5 mm² for lighting, 2.5 mm² for sockets, 6 or 10 mm² for cookers and showers. The final size depends on BS 7671 design.
- Use 3 core and earth for two-way lighting, SWA for buried or outdoor runs, and flex for appliances.
- New colours are brown (live), blue (neutral) and green/yellow (earth). Old installations use red and black.
- LSZH and fire-resistant cables are for specific locations and life-safety circuits, not every room.
Choosing the best electrical cable for your home
The best electrical cable for home wiring is the one that suits the circuit, the route and the regulations. For most jobs that means twin and earth in the right size, with 3 core and earth, SWA, flex or fire-resistant cable where the job calls for them. If you are unsure what a circuit needs, ask a qualified, registered electrician. For a broader look at circuits and consumer units, read our guide to the basics of electrical wiring.
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FAQs
What is the best cable for house wiring in the UK?
For most fixed wiring in UK homes the best choice is PVC twin and earth cable (6242Y). It is used for lighting, sockets, cookers and showers. Use 3 core and earth for two-way lighting, SWA armoured cable for buried or outdoor runs, and flexible cable to connect appliances. Final sizes must follow BS 7671 design.
What size cable is used for sockets in a UK house?
Socket ring final circuits are normally wired in 2.5 mm² twin and earth on a 32 A MCB or RCBO. A 20 A radial circuit also typically uses 2.5 mm², while a 32 A radial usually needs 4 mm². The installation method, run length and insulation can change the size needed.
What size cable do I need for lighting?
Most domestic lighting circuits use 1.0 mm² or 1.5 mm² twin and earth on a 6 A breaker. 1.5 mm² is often chosen for longer runs to limit voltage drop. Two-way and intermediate switching uses 3 core and earth between the switches. Always check the design against BS 7671.
What size cable do I need for an electric shower?
Most electric showers between about 8.5 kW and 10.5 kW are wired in 10 mm² twin and earth on a 40 A to 50 A breaker. Smaller showers on short runs may use 6 mm². The exact size depends on the shower rating, the run length and how the cable is installed, so have it designed by an electrician.
When should I use SWA cable instead of twin and earth?
Use steel wire armoured (SWA) cable when the cable is buried, run outside or likely to be damaged, for example to a garage, garden office, outdoor lights or an EV charger. Twin and earth is not designed for burial or exposed outdoor runs. SWA needs proper glands so the armour is earthed.
What are the colours of UK electrical wires?
Since 2004 UK fixed wiring uses brown for live, blue for neutral and green/yellow for earth. Homes wired before about 2006 may have red for live and black for neutral. In 3 core and earth cable the cores are brown, black and grey, so black can be live in newer wiring.
Do I need LSZH or fire-resistant cable in my house?
Usually not for ordinary circuits. Standard PVC twin and earth is fine for most homes. LSZH cable is specified where smoke and toxic fumes would be a danger, such as escape routes and public buildings. Fire-resistant cable is needed for fire alarm and emergency lighting systems where the design calls for it.