What cable size for commercial EV chargers?

Depends on charger power and whether load-managed. 7kW charger: 6mm² on 32A. 22kW charger: 6mm² three-phase on 32A per phase. With load management, cable can be sized to managed maximum rather than charger rating. Distribution boards need to handle total possible load.

How many EV chargers can my building support?

Calculate existing maximum demand, subtract from supply capacity. Remaining capacity ÷ charger power = maximum chargers without management. With load management, you can install more chargers sharing the available power. Typical office might support 4-8 chargers on 100A three-phase supply.

Do I need load management for workplace charging?

Recommended for 3+ chargers, essential for larger installations. Without it, simultaneous charging can exceed supply and trip main breakers. Load management shares power intelligently - cars charge slower but everyone gets charged. Often required by DNO for connection approval.

What's the difference between 7kW and 22kW chargers?

7kW (single-phase, 32A) adds ~25 miles range per hour. 22kW (three-phase, 32A per phase) adds ~75 miles per hour. Most workplace parking suits 7kW - staff park all day. 22kW better for visitors or short-stay parking. Many EVs can't accept 22kW anyway.

Do I need DNO approval for commercial EV chargers?

Likely yes. Single 7kW chargers may fall under G98 notification. Multiple chargers or higher power usually need G99 application. DNO assesses network capacity - may require reinforcement at your cost. Start the application early - can take months.

What about rapid chargers (50kW+)?

Rapid chargers need substantial power - 50kW = 72A three-phase, 150kW = 217A three-phase. Often need dedicated supply connection or HV supply. Not practical for most workplaces. Typical for service stations, public hubs, and fleet depots with quick turnaround.

What regulations apply to commercial EV charging?

BS 7671 Wiring Regulations, Building Regulations Part S (EV charging in new buildings), IET Code of Practice for EV Charging, G98/G99 for grid connection, Workplace (Health, Safety and Welfare) Regulations for installation location. Listed buildings may have planning restrictions.

Can I use existing car park lighting circuits?

No - EV chargers need dedicated circuits. Car park lighting circuits aren't rated for continuous EV charging loads. You can share distribution infrastructure (containment, routes) but circuits must be separate. May need new feeder cables to car park distribution point.

What about payment systems and network connectivity?

Commercial chargers usually need network connection for payment, monitoring, and load management. Consider: mobile signal (SIM-based), WiFi, or Ethernet. Back-office systems handle billing. Budget for ongoing software/service subscriptions beyond hardware costs.

How do Building Regulations Part S affect new buildings?

New non-residential buildings with 10+ parking spaces must have at least one charger and cable routes to 20% of spaces. Major renovations trigger similar requirements. Must be at least 7kW capable. This affects electrical design from early planning stage.

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Commercial EV Charging Cable Sizing Calculator

Calculate the correct cable size for workplace EV chargers, car parks, and fleet charging installations

Commercial EV Charging Cable Quick Facts

Workplace chargers typically 7kW-22kW per point
Rapid chargers (50kW+) need dedicated HV or large LV supply
Load management essential for multiple charger installations
Three-phase common for commercial installations
Building Regulations require EV charging provision in new builds

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)

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Common Commercial EV Installations

Small workplace (2-4 chargers, 7kW)

Existing supply may suffice, 32A per charger, load management

Medium car park (5-10 chargers)

Likely supply upgrade, three-phase distribution, smart load management

Large car park (10+ chargers)

Dedicated EV distribution board, dynamic load management, possible DNO upgrade

Fleet depot (overnight charging)

Can use lower power (3.6-7kW) with longer charge times, schedule optimization

Rapid charger (50kW+)

Dedicated supply, often requires DNO upgrade or new connection

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For domestic installations, see our home EV charger calculator. Caravan sites and holiday parks have similar multi-charger requirements - check our hookup guide. Pair commercial EV charging with solar PV for reduced energy costs.

Commercial EV Charging Cable Sizing

Commercial EV charging cable sizing calculates conductor sizes for workplace and car park charger installations. Unlike domestic single-charger installs, commercial sites need multiple chargers with load management. Total site demand can reach 100s of kW, requiring careful supply assessment and often three-phase distribution with smart power sharing.

Commercial EV Charging Installation Costs (2024)

Typical UK costs. Excludes DNO upgrade costs which vary significantly.

Installation Scenario	Materials	Labour	Total
Single 7kW workplace charger	£600-1000	£400-700	£1000-1700
Single 22kW workplace charger	£1200-2000	£600-1000	£1800-3000
Car park installation (4 × 7kW)	£3500-6000	£2500-4000	£6000-10000
Load management system	£500-1500	£300-600	£800-2100
Supply upgrade for EV charging	£2000-5000	£1000-2500	£3000-7500

Prices as of 2024. WCS grant may offset up to £350 per socket (check current eligibility).

Load Management for EV Charging

Load management (smart charging) shares available power across multiple chargers, preventing supply overload. Static load management sets fixed power per charger. Dynamic load management adjusts in real-time based on building demand and charger usage. Essential for sites where charger count exceeds supply capacity.

Workplace Charging Scheme (WCS)

The Workplace Charging Scheme offers vouchers of up to £350 per socket (max 40 sockets) towards purchase and installation of workplace EV chargers. Businesses, charities, and public sector organisations qualify. Covers chargers from 7kW. Must use OZEV-approved installer. Check current scheme status and requirements before quoting.

EV Charging Modes

Mode 2: Portable charger to standard socket (emergency use, not for commercial). Mode 3: Dedicated EV charger with Type 2 connector - standard for UK AC charging, 7-22kW. Mode 4: DC rapid charging with CHAdeMO or CCS connector - 50kW+. Commercial installations are Mode 3 or Mode 4. Mode 3 is most common for workplace charging.

Frequently Asked Questions

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