EV Charging Point Installation: OZEV, BS 7671, and Type 2 Charger Wiring — A UK Electrician's Guide

Electric vehicle (EV) charging point installation has become one of the fastest-growing sectors for UK electricians. The government's ban on new petrol and diesel car sales from 2035 (now confirmed) and growing EV adoption mean demand for home and workplace chargers is accelerating. This guide covers the technical requirements, regulatory framework, and practical wiring considerations for domestic and light commercial EV charge point installation.

Types of EV Charging

Mode 2 — Occasional Use (Not Recommended for Permanent Install)

A standard 3-pin plug (13 A socket) with an in-cable control box (ICCB). Maximum 2.3 kW. Slow charging — typically 15–24 hours for a full charge. Not suitable as a primary charging method. No dedicated circuit required but should not be used via extension lead. BS 7671 does not prohibit this but it is not endorsed for regular overnight charging due to thermal risk on domestic socket outlets.

Mode 3 — Dedicated EVSE (Standard Domestic/Commercial)

A dedicated Electric Vehicle Supply Equipment (EVSE) unit hard-wired or via a Type 2 socket. Standard domestic single-phase units: 3.6 kW (16 A) or 7.4 kW (32 A). Three-phase commercial: 11 kW (16 A per phase) or 22 kW (32 A per phase). Most home chargers installed today are 7.4 kW single-phase. Full charge time: 4–8 hours for a typical 40–80 kWh battery EV.

Mode 4 — DC Rapid Charging

Direct current fast charging (DCFC): 50 kW, 100 kW, 150 kW, or higher. Requires three-phase supplies, specialist equipment, and DNO agreement. Not typically installed by domestic electricians — commercial specialist territory.

Regulatory Framework

BS 7671:2018+A2:2022 — Section 722

Section 722 of the 18th Edition Wiring Regulations covers supply of electric vehicles. Key requirements:

• Every socket outlet or vehicle connector used for EV charging must be protected by an RCD with a residual operating current not exceeding 30 mA
• Socket outlets and vehicle connectors must be protected individually where reasonably practicable
• A time-delay function is permitted (but not required) for smart charging
• EV charging installations in locations accessible to the public require Type B RCD protection (or equivalent combination) — DC fault protection is required
• For domestic (non-public) installations: Type A RCD is acceptable if the EVSE unit provides DC fault detection (most modern units do via onboard monitoring)
• Cables must be suitable for continuous operation at the rated current (IEC 61851-1)

IET Code of Practice for EV Charging Equipment Installation

The IET CoP (currently 4th edition) is the industry reference for EV charger installation. It covers site survey requirements, cable sizing, earthing arrangements, and competence requirements. Although not a statutory document, it is referenced by OZEV grant conditions and NAPIT/NICEIC scheme requirements.

OZEV (Office for Zero Emission Vehicles) — EVHS Grant

The Electric Vehicle Homecharge Scheme (EVHS) closed to single-unit dwellings in April 2022 but the EV Infrastructure Grant for residential landlords and flat owners remains active (subject to conditions). Workplace and residential landlord grants are available for eligible installations. Key installer requirements:

• Installer must be registered with an OZEV-authorised body (NAPIT EV, NICEIC EV, SELECT EV, or equivalent)
• EVSE unit must be on the OZEV approved products list
• Smart functionality required — unit must be capable of off-peak charging and demand-side response
• Charger must have a 3-year warranty minimum
• Installation must comply with BS 7671 and IET CoP

Part P — Building Regulations

EV charger installation is notifiable under Part P in England. The circuit feeding the EVSE is a new electrical circuit and must be self-certified via a Competent Person Scheme (NICEIC, NAPIT, ELECSA) or notified to Building Control. A Building Regulations Compliance Certificate must be issued to the homeowner. Do not skip this step — it affects property sale/mortgage valuations.

DNO Notification

Single-phase domestic installations up to 3.68 kW (16 A) do not require DNO notification in most areas. Installations above 3.68 kW (including standard 7.4 kW single-phase chargers) may require G99 or G98 notification depending on the DNO. Check your local DNO's connection requirements — many now have online tools. G99 application is required for 7.4 kW+ installations with some DNOs. Failure to notify can result in the DNO requiring removal.

Site Survey

A thorough site survey is essential before quoting. Key checks:

• Incoming supply size: Most domestic properties have 100 A single-phase. Confirm with the incoming supply fuse rating. A 7.4 kW charger draws 32 A — confirm remaining headroom with concurrent loads (cooker, shower, heating).
• Consumer unit capacity: Space for a new 32 A RCBO or MCB. If the consumer unit is full, a new enclosure or sub-board may be needed.
• Earthing arrangement: Confirm TN-S, TN-C-S (PME), or TT. PME earthing presents specific risks for EV charging — see below.
• Cable route: Measure distance from consumer unit to proposed charger location. Identify obstacles, ground conditions for buried cables, and any planning constraints.
• Charger location: Garages (ventilated), carports, or external wall-mounted. IP rating requirements differ.
• Smart meter: Confirm if smart meter/SMETS2 is installed — relevant for smart tariff integration.

PME Earthing and EV Charging

This is a critical safety issue. Most UK domestic properties use PME (Protective Multiple Earth, also known as TN-C-S) earthing. Under PME, the neutral and earth are combined at the supply intake. This presents a risk for external EV charging: if the DNO neutral becomes open-circuit (broken neutral), the chassis of the vehicle can rise to a dangerous voltage referenced to true earth.

BS 7671 Section 722 and the IET CoP require that for EV charging equipment in locations accessible to the public (and recommended for domestic external locations under PME), one of the following must be applied:

• Supplementary earth electrode at the EVSE location (earth rod), with the EVSE earthed to both the PME earth and the rod. The EVSE must include protection to disconnect if the neutral/earth voltage rises above a threshold (typically >70 V). This is built into most modern EVSE units.
• Local earth electrode only (effectively converting the EVSE supply to TT), with RCD protection.
• Some manufacturers provide built-in neutral-earth monitoring — confirm with specific EVSE datasheet.

For garage installations within the property (connected to the main earth), PME risk is lower but earthing must still comply with BS 7671 requirements. Always document the earthing arrangement on the installation records.

Cable Selection and Sizing

Cable Rating

A 7.4 kW (32 A) charger on a single-phase supply requires a circuit capable of continuous 32 A operation. The circuit is typically treated as a continuous load (EV charging can run for 4–8 hours). Cable selection:

• Internal route (consumer unit to garage, all enclosed in thermal insulation): 10 mm² two-core + earth T&E may be required
• Standard internal route (clipped direct or in conduit, not insulated): 6 mm² two-core + earth T&E is typically adequate for runs up to ~20 m with a 32 A RCBO
• External buried cable: SWA (steel wire armoured) or MDPE-ducted T&E/singles. SWA 6 mm² two-core is the standard choice for direct burial
• Always check volt drop — maximum 3% for final circuits. At 32 A over 20 m with 6 mm²: approximately 1.5 V drop (0.65% on 230 V) — acceptable. Longer runs or higher resistance paths require 10 mm².

Buried Cable Requirements

• Minimum depth: 500 mm under paved areas not subject to vehicular traffic; 600 mm under areas subject to vehicular traffic
• Cable route marker tape above cable
• Avoid running parallel to gas pipes (minimum 25 mm clearance)
• SWA cable armour should be earthed at both ends (standard practice for runs >3 m)
• If using T&E in conduit, ensure conduit is suitable for external/buried use (MDPE or rigid PVC suitable for ground)

Overcurrent and RCD Protection

RCBO vs MCB + RCD

The preferred arrangement is a Type A RCBO (combined MCB + RCD) at the consumer unit, providing:

• 30 mA RCD protection (as required by BS 7671 722.531)
• Overcurrent protection (32 A)
• Individual circuit protection (no nuisance tripping affecting other circuits)

If the EVSE unit includes onboard Type B equivalent DC protection, a Type A RCBO is sufficient for domestic use. For locations accessible to the public, a Type B 30 mA RCD is required at the supply point (or equivalent EV-specific protection device).

Consumer Unit Considerations

Modern split-load consumer units typically accommodate an RCBO in the main busbar. Where the consumer unit is full, options include:

• Tandem (piggyback) MCB where permitted by the manufacturer
• Replace with a larger unit (if economically justified)
• Install a secondary distribution board fed from a spare way or the existing incomer tails (requires a new split metered arrangement or sub-distribution)

Always check consumer unit manufacturer guidance before installing tandem devices — not all consumer units permit this.

EVSE Unit Selection

Key selection criteria for domestic 7.4 kW EVSE units:

• Smart charging: OZEV grant conditions require OCPP-compliant smart functionality. Units must support scheduled charging and demand-side response. Popular units: Andersen A2, Ohme Home Pro, Zappi (myenergi), Ohme ePod, Pod Point Solo 3.
• Solar PV integration: If the property has solar PV, consider a unit with PV divert capability (e.g., Zappi) to preferentially charge from solar export.
• Tethered vs untethered: Tethered units have a fixed Type 2 cable (more convenient for home use). Untethered units have a Type 2 socket (more flexible — driver uses their own cable). Tethered is standard for domestic.
• IP rating: Minimum IP44 for external installation; IP65 recommended for exposed locations.
• Cable management: Retracting/storage features for the charging cable.
• Load balancing: Units with load balancing monitor the main supply and reduce charger output to prevent the incomer from being overloaded — essential for properties with limited headroom.

Typical Domestic Installation Procedure

1. Confirm earthing arrangement — TN-S, TN-C-S, or TT. Install earth electrode if required for PME mitigation.
2. Isolate consumer unit supply — confirm dead with approved voltage indicator.
3. Install RCBO — Type A, 32 A, 30 mA, in consumer unit. Run cable from RCBO to charger location.
4. Route cable — clip to joists internally, run in conduit through walls, bury externally in SWA at correct depth.
5. Mount EVSE unit — appropriate back plate/wall anchor to masonry or timber at correct height (typically 750–1200 mm to cable entry point). Ensure cable entries are sealed if external.
6. Connect supply cable to EVSE — follow manufacturer wiring diagram. Connect earth to EVSE earth bar.
7. Reinstate consumer unit — connect to RCBO line and neutral. Verify correct torque on terminals.
8. Dead tests — insulation resistance (L-N, L-E, N-E at 500 V DC), continuity of earth (R1+R2 and R2).
9. Energise and test — RCD functional test (press test button; verify trip time with loop tester if accessible). Verify EVSE powers on, connects to app/network.
10. Earth electrode test — if external earth rod installed, measure earth resistance (target <200 Ω for supplementary electrode).
11. Complete documentation — Minor Works or EICR Schedule of Inspections as appropriate. Notify via Competent Person Scheme. Issue to customer.

Inspection and Testing Requirements

Test and record per BS 7671 Chapter 64:

• Continuity of protective conductors: R1+R2 method
• Insulation resistance: ≥1 MΩ (typically >200 MΩ for a new circuit)
• Polarity: verify line-neutral correct at EVSE terminal and at Type 2 socket/tethered connection point
• Earth fault loop impedance (Zs): confirm fault current is sufficient to operate the 32 A RCBO within permitted disconnection time. For 32 A Type B MCB: Zs max = 1.37 Ω (from BS 7671 Table 41.3). Typical domestic loop impedance 0.3–0.8 Ω + cable resistance.
• RCD operation: test at rated operating current — must trip within 300 ms. At 5× rated current — must trip within 40 ms.

Workplace and Multi-Residential Charging

For workplace car parks and multi-residential (flats, HMOs) the requirements differ:

• Building Regulations Part S (England, Wales): new non-residential buildings and major renovations with >10 parking spaces must provide EV charge points and cable routes for future installation. Minimum 1 in 5 spaces with active charging.
• Sub-metering is advisable for cost allocation between tenants or employees
• OCPP back-end management system required for OZEV workplace grants
• Load management across multiple chargers — use a smart charge management system to prevent overloading the incoming supply
• Three-phase chargers (11 kW, 22 kW) require three-phase supply — confirm availability with DNO

Key Standards and References

• BS 7671:2018+A2:2022 — 18th Edition Wiring Regulations, Section 722
• IET Code of Practice for EV Charging Equipment Installation (4th edition)
• IEC 61851-1 — EV conductive charging system requirements
• IEC 62196-2 — Type 2 connector standard
• BS EN 61439-7 — EV charging station assemblies
• OZEV EVHS/REFA grant guidance — OZEV.gov.uk
• G98/G99 — Engineering Recommendation for DNO connection of microgenerators/EVSE
• Building Regulations Part P — Electrical safety in dwellings
• Building Regulations Part S — Infrastructure for charging electric vehicles (2022)

Related APM Guides

• Consumer Unit Replacement: 18th Edition, RCBO vs RCD
• UK Electrical Cable Types: T&E, SWA, Flex
• Earth Bonding and Equipotential Bonding
• Electrical Installation Testing: Continuity, Insulation Resistance, Loop Impedance
• Surge Protection Devices (SPDs) and AFDDs
• Fused Connection Units
• Wiring Accessories: Sockets, Switches, Dimmers, and USB Outlets

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