What cable size do I need for a 7kW EV charger?

Most 7kW EV chargers need 6mm² twin and earth cable for runs up to about 18 meters. For longer runs (18-30m), upgrade to 10mm² to keep voltage drop under 5%. The charger draws 32A at full power, so the cable must handle this continuously without overheating.

Can I use 4mm² cable for an EV charger?

No, 4mm² is undersized for a 7kW (32A) EV charger. It can only handle 24A in ideal conditions (Method C). Using undersized cable creates fire risk and will fail EICR inspection. Always use minimum 6mm² for 32A circuits.

How do I calculate voltage drop for EV charger cable?

Voltage drop = (current × length × mV/A/m) ÷ 1000. For 6mm² at 32A over 15m: (32 × 15 × 7.3) ÷ 1000 = 3.5V (1.5%). This is within the 5% limit. Our calculator does this automatically and recommends larger cable if needed.

Does an EV charger need its own circuit?

Yes, every EV charger must have a dedicated circuit from the consumer unit with its own MCB (typically 32A Type B or C) and RCD protection (30mA Type A or better). This is required by BS 7671 and the IET Code of Practice for EV Charging.

What MCB do I need for a 7kW EV charger?

32A MCB, typically Type B for domestic installations. Type C may be specified by some charger manufacturers. The MCB must be combined with 30mA RCD protection - a Type A RCD minimum, though Type B RCDs provide better DC fault protection.

Can I install an EV charger on a ring main?

No, EV chargers must never be connected to a ring main or spur. They require a dedicated radial circuit from the consumer unit. This ensures the circuit can handle continuous 32A load without affecting other circuits.

What about three-phase 22kW chargers?

22kW chargers require three-phase supply (not available in most UK homes). They draw 32A per phase and need 6mm² four-core cable (or 10mm² for longer runs). DNO notification and often an upgraded supply are required.

Do I need to notify the DNO for EV charger installation?

Yes, all EV charger installations must be notified to the Distribution Network Operator (DNO) via the ENA connection application. This is a legal requirement under G98/G99. Your installer should handle this notification.

How long does it take to install an EV charger?

A straightforward installation (charger near consumer unit, no upgrades needed) takes 2-4 hours. Complex installs requiring consumer unit upgrades, long cable runs, or groundwork can take a full day or more.

Is SWA cable required for EV charger installation?

SWA (Steel Wire Armoured) cable is required when the cable is buried underground, run externally, or needs mechanical protection. For internal runs in conduit or trunking, standard twin and earth is acceptable. Always follow BS 7671 for cable selection.

Back to Cable Sizing Calculator

EV Charger Cable Sizing Calculator

Calculate the correct cable size for EV charger installations - 7kW, 11kW and 22kW home and commercial chargers

EV Charger Cable Quick Facts

7kW charger = 32A (most common UK home install)
22kW charger = 32A three-phase
Typical cable run: 10-20m from consumer unit
6mm² minimum for 32A, 10mm² for longer runs
OZEV grant covers up to £350 (landlords/renters)

Cable Size Calculator

BS 7671:2018+A2:2022 compliant

1. Load Current

2. Cable Length (meters)

3. Installation Method

Lighting circuit (3% voltage drop limit)

Need a Qualified Electrician?

Get quotes from vetted, local contractors for your EV charger installation

Get Free Quotes

Common EV Charger Installations

7kW home charger (single-phase)

32A circuit, 6mm² cable for runs under 18m, 10mm² for longer

3.6kW charger (granny charger upgrade)

16A circuit, 2.5mm² cable typically sufficient

22kW charger (three-phase)

32A per phase, 6mm² three-phase cable, dedicated supply

Long run to detached garage (25m+)

10mm² or 16mm² to manage voltage drop

Multiple EV chargers

Load management system, possible DNO upgrade

Complete Your Home Electrification

EV charging often goes hand-in-hand with solar PV and battery storage to maximise self-consumption and reduce charging costs. Many customers also install air source heat pumps as part of whole-home electrification. For garage installations, check our garage and workshop electrical guide.

EV Charger Cable Sizing

EV charger cable sizing determines the correct conductor cross-sectional area (mm²) needed to safely supply an electric vehicle charging point. Most UK home chargers are 7kW (32A single-phase) requiring 6mm² or 10mm² cable depending on cable run length. Correct sizing ensures BS 7671 compliance, prevents overheating, and keeps voltage drop within the 5% limit for reliable charging.

EV Charger Installation Costs (2024)

Typical UK installation costs including cable, labour, and consumer unit work. Excludes charger unit cost (£300-800).

Installation Scenario	Materials	Labour	Total
7kW charger, short run (<10m)	£80-120	£200-350	£280-470
7kW charger, medium run (10-20m)	£120-180	£300-450	£420-630
7kW charger, long run (20-30m)	£180-280	£400-550	£580-830
22kW three-phase install	£300-500	£600-900	£900-1400
Consumer unit upgrade required	£150-300	£200-350	£350-650 (additional)

Prices as of 2024. Actual costs vary by region, complexity, and supplier. OZEV grant can reduce costs by up to £350 for eligible installations.

OZEV Grant

The Office for Zero Emission Vehicles (OZEV) provides grants towards EV charger installation costs. As of 2024, the EV chargepoint grant offers up to £350 for landlords, renters, and people living in flats. The grant covers charger and installation costs for approved chargers installed by OZEV-approved installers.

Type A vs Type B RCD

Type A RCDs detect AC and pulsating DC fault currents - suitable for most EV chargers. Type B RCDs also detect smooth DC fault currents, providing better protection for chargers without built-in DC protection. Some chargers have internal DC protection allowing Type A RCDs. Check manufacturer specifications.

Smart Charger Requirement

Since June 2022, all home EV chargers sold in the UK must be "smart" chargers under the Electric Vehicles (Smart Charge Points) Regulations 2021. Smart chargers can be remotely controlled, schedule charging for off-peak times, and respond to grid demand. This is mandatory for OZEV grant eligibility.

Frequently Asked Questions

Related Electrical Calculators

Voltage Drop Calculator

Verify voltage drop for long EV charger cable runs

Cable Sizing Calculator

Full BS 7671 cable sizing for all circuits

Get Quotes from Local Electricians

Looking for a qualified electrician for your EV charger installation? Tell us about your project and we'll connect you with vetted contractors in your area. Free, no obligation quotes.

Trade professional or electrical business? Use the form above and let us know - we offer lead referrals in your area, bulk calculation tools, and white-label partnerships for merchants and suppliers.

More Electrical Calculators

Voltage drop, conduit fill, earth fault loop impedance and more. All BS 7671 compliant, all free.

View All Calculators