What Size Cable Do I Need for an EV Charger?

For a standard 7kW home charger, the fixed supply cable an electrician runs from your consumer unit to the wallbox is typically 6mm2 for ordinary run lengths, stepping up to 10mm2 for longer runs or to keep voltage drop within limits. There is no single correct answer for your home: the exact size depends on the run length, installation method, how cables are grouped, ambient temperature and more, and it must be calculated by a qualified electrician to BS 7671. If you actually mean the charging lead that plugs your car into the charge point, that is sized by length and connector type instead, and you can see the full range of guides below for both meanings.

Supply cable or charging lead: which "cable" do you mean?

The word "cable" causes most of the confusion here, because it describes two completely different things. Getting the right one is the single most important step before you read any further.

The supply (install) cable

This is the fixed wiring an electrician runs from your fuse box, also called the consumer unit, out to the wallbox. It is measured in mm2 (the cross-sectional area of the copper conductor), it is chosen and fitted by a qualified installer, and it stays in the wall or the ground for the life of the charger. This is almost always what people mean when they search "what size cable for an EV charger".

The charging cable (the lead)

This is the Type 2 lead that connects your car to the charge point. It is measured in length (metres) and current (amps), not mm2, and you unplug it and coil it away after every charge. This is the part we make. If length is what you are after, our EV charging cable length guide walks you through it, and you can shop charging leads by car directly.

We make EV charging cables, which is the lead. We do not make or fit the installation wiring. For the supply cable and the install itself, use a qualified EV installer. The rest of this guide covers the supply side in general terms so you know what to expect, then points lead buyers to the right place.

What size supply cable does a 7kW charger need?

A standard home wallbox is 7kW, which is 32A on a single-phase 230V AC supply. You will also see this written as 7.4kW, which is the same thing rounded. For that load, 6mm2 cable is common on ordinary run lengths, and 10mm2 is used where the run is longer or where voltage drop needs to be kept within the limits in BS 7671.

Please treat those as typical starting points, not a specification for your home. The installer confirms the final size after looking at the run length, the installation method (clipped, buried, in conduit), whether the cable is grouped with others, the ambient temperature and the protective device. For a deeper look at that single-phase decision, see our dedicated guides on what size cable a 7kW charger needs and 6mm vs 10mm cable.

What about a 22kW charger?

22kW charging is three-phase, drawing roughly 32A per phase. Most UK homes are single-phase, so they cannot run a 22kW charger at home without a three-phase supply upgrade, which is uncommon, expensive and has to go through the DNO. A 22kW install uses a multi-core cable, for example a 5-core SWA, sized to the installer's design rather than a figure you can read off a chart.

Before you assume you need 22kW, it is worth checking whether it would help at all. Many cars charge no faster than 7kW or 11kW on AC regardless of the wallbox. Our guides on 7kW vs 22kW and whether you actually need a 22kW cable cover this, and single-phase vs three-phase charging explains the supply side. If you have confirmed a three-phase supply, the sizing details are in what size cable a 22kW charger needs.

Charger output and typical supply cable: a reference table

The table below is a rough guide to what tends to get specified. It is not a substitute for a design to BS 7671. Your electrician confirms the correct size for your specific install.

SWA or twin-and-earth: which cable type?

Cable type matters as much as the mm2. The two you will hear named are SWA and twin-and-earth, and they are not interchangeable for every run.

SWA (steel-wire armoured) cable is used for outdoor, buried or exposed runs, because the steel armour gives mechanical protection and an earth path. Twin-and-earth (T&E) is only suitable for protected indoor runs where it cannot be damaged. Where a cable is buried, it must be at an adequate depth with warning tape and mechanical protection in line with the regs, and the installer judges all of that on site. We are deliberately not quoting a burial depth here, because it is a design decision, not a fixed number.

Why does run length (voltage drop) change the size?

The longer the cable run, the more the voltage drops along it, and BS 7671 sets limits on how much drop is acceptable. To stay within those limits, a longer run often means going up a conductor size, which is exactly why 10mm2 appears on jobs where 6mm2 would otherwise have been fine. The distance from your consumer unit to where the wallbox will sit is therefore one of the first things a good installer measures.

There is no universal distance threshold we can give you. The point at which you step up a size depends on the whole circuit design, so treat run length as a reason to expect a conversation with your electrician, not a figure to calculate yourself. If you want to explore the variables, see our EV charger cable size calculator guide and our overview of how to run a cable for an EV charger.

Who is allowed to fit the supply cable?

Installing or altering an EV charge point circuit in England and Wales is notifiable work under Part P of the Building Regulations. It must be carried out by a registered competent person, for example an installer registered with NICEIC, NAPIT or Stroma, or otherwise notified to building control. Scotland and Northern Ireland have their own equivalent rules.

DIY is only legal if the work fully complies and is properly notified and inspected, and we strongly discourage it for EV circuits given the current and safety involved. In practice, using a registered EV installer is the sensible route, and our guide on what to expect from a home charger installation walks through the process.

What about the DNO, the main fuse and load management?

Your installer also notifies the Distribution Network Operator (DNO) for an EV charge point. Some supplies or higher outputs need the DNO's approval before work can start, which can add time to the job, so it is worth factoring in.

There is also the question of whether your existing supply can take another 32A or so. If the main fuse or supply cannot, the installer may fit a CT-clamp load manager, which makes the charger back off when the house is drawing heavily, rather than going to the expense of a supply upgrade.

I just want the right lead: what size do I need?

If "size" for you really means the charging lead, the two things that matter are length and connector. Around 5m suits most driveways, with 7.5m or 10m for awkward parking or a charge point that is not right next to the car. The connector depends on your car's inlet, which is Type 1 or Type 2, and the lead's current rating.

One thing worth knowing: a longer or heavier lead never makes the car charge faster than its onboard limit. Pick the length that reaches comfortably and the connector that fits your car. Our length guide covers this, and you can browse charging cables by car to find the right one.

Related tool: that is the fixed circuit cable your electrician sizes. If you also need a portable Type 2 charging lead, our cable length calculator works out the right length to buy.

Frequently asked questions

What size cable is required for an EV charger in the UK?

For a 7kW single-phase charger drawing around 32A, 6mm2 supply cable is common on ordinary run lengths, with 10mm2 used for longer runs or to keep voltage drop within limits. The exact size depends on run length, installation method, grouping and ambient temperature, and must be confirmed by a qualified electrician to BS 7671.

Is 6mm cable enough for a 7kW EV charger?

6mm2 is often enough for a 7kW charger on an ordinary run length, but not always. Longer runs or tighter voltage drop limits can mean stepping up to 10mm2. Only your installer can confirm the correct size after designing the circuit to BS 7671.

What size cable do I need for a 22kW charger?

22kW charging is three-phase, so it needs a three-phase supply that most UK homes do not have. Where one exists, the install typically uses a multi-core cable such as a 5-core SWA, sized to the installer's design rather than a standard figure.

Do I need SWA or twin-and-earth cable for an EV charger?

SWA (steel-wire armoured) cable is used for outdoor, buried or exposed runs because it gives mechanical protection. Twin-and-earth is only suitable for protected indoor runs. The installer decides based on the route and how the cable is protected.

Can I install the EV charger supply cable myself?

Installing or altering an EV charge point circuit in England and Wales is notifiable work under Part P and must be done by a registered competent person or notified to building control. Scotland and Northern Ireland have their own rules. DIY is strongly discouraged for EV circuits.

Is "electric car charger wire" the cable or the lead?

It can mean either. The supply cable is the fixed mm2 wiring an electrician runs to the wallbox. The charging lead is the Type 2 cable between your car and the charge point, sized by length and connector. If you want a lead, our length guide and charging cable range will help.