Everything you need to know about the IET Code of Practice for Electric Vehicle Charging Equipment Installation. Load assessment, earthing (PME and TT), O-PEN protection, cable sizing, smart charging regulations, OCPP, and documentation requirements.
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Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.
The IET Code of Practice for Electric Vehicle Charging Equipment Installation is the UK industry-standard guidance for installing EV charge points. It sits alongside BS 7671 Section 722 and covers supply arrangements, earthing — especially the PME (broken-PEN) risk — load and demand management, RCD selection with DC fault detection, and installation, testing and handover. It is the reference most schemes and manufacturers expect installers to follow.
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The IET Code of Practice for Electric Vehicle Charging Equipment Installation is a technical guidance document that supplements BS 7671:2018+A4:2026 with specific requirements for the design, installation, verification, and maintenance of EV charging equipment. The current edition is the 5th Edition, published in 2023.
The Code of Practice (CoP) exists because EV charging installations present unique technical challenges that are not fully addressed by BS 7671 alone. These include outdoor earthing risks on PME supplies, the need for load management on multiple charger installations, DC fault current protection, communication protocols, and the interaction between the vehicle, charger, and electrical installation.
While the CoP is not a British Standard and compliance is not a strict legal requirement, it is the accepted industry standard. All major competent person schemes (NICEIC, NAPIT, ELECSA) expect EV charger installations to follow the CoP. Building control bodies and OZEV (the Office for Zero Emission Vehicles, formerly OLEV) grant funding applications reference the CoP as the baseline technical standard. An electrician who installs an EV charger without following the CoP is leaving themselves exposed to liability if something goes wrong.
The CoP covers all types of EV charging: domestic single chargepoints, workplace charging with multiple units, public charging infrastructure, fleet depot installations, and rapid DC charging. It addresses both Mode 3 (AC charging via a dedicated chargepoint) and Mode 4 (DC rapid charging) installations.
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Before installing any EV charger, a thorough load assessment of the existing electrical installation is essential. The purpose is to determine whether the existing supply has sufficient capacity to support the additional load of the EV charger without exceeding the main fuse or supply capacity.
A domestic 7 kW charger draws 32 A — which is a significant addition to a typical domestic supply protected by a 60 A or 80 A main fuse. If the existing maximum demand (including the cooker, shower, heating, and other large loads) is already close to the main fuse rating, adding a 32 A EV charger could cause the main fuse to blow during periods of high demand.
If the existing supply cannot support the EV charger even with load management, the options are: request a supply upgrade from the DNO (which can take weeks and cost thousands), install a lower-power charger (for example, 3.6 kW at 16 A instead of 7 kW at 32 A), or install a dedicated three-phase supply if one is available.
Earthing is the most technically critical aspect of EV charger installation. The IET CoP dedicates significant attention to this topic because of the specific risks associated with outdoor charging on PME (TN-C-S) supplies.
The fundamental problem: in a PME system, the earth and neutral are combined in the supply cable (the PEN conductor). If this PEN conductor breaks between the DNO transformer and the property, all metalwork connected to the PME earth could rise to mains potential relative to true earth. A person standing outdoors on damp ground while touching the vehicle or charger could receive a fatal electric shock.
BS 7671:2018+A4:2026 Reg 722.312.2.1 requires that no PEN conductor shall form part of the circuit supplying EV charging equipment. On a TN-C-S (PME) supply this means the EV circuit must originate downstream of the main bonding point where PE and N are already separate conductors — combined PEN wiring must not extend into the EV final circuit. PME earthing must not be used for EV charging where the user is outdoors unless additional protective measures (O-PEN device, TT earth, or separation) are installed. The IET CoP is clear on this point.
Install an O-PEN detection device that monitors the PEN conductor and disconnects the EV charging circuit if continuity is lost. This allows the PME earth to be used for the general installation while protecting the EV circuit specifically. Most commonly used solution.
Install a separate earth electrode (TT earthing) for the EV charging circuit. The EV circuit uses its own earth rod rather than the PME earth. Requires an RCD for fault protection and the earth electrode resistance must be verified. Independent of the supply earth.
Use a charger and charging cable that are double insulated (Class II) throughout the entire charging path, eliminating the need for a protective earth conductor to the charger metalwork. Limited availability — most chargers are Class I.
BS 7671:2018+A4:2026 Reg 722.413.1.2 permits a fixed isolating transformer (complying with BS EN 61558-2-4) to supply a Class I EV charging point from a separated, unearthed source. This arrangement is limited to supplying one vehicle from one unearthed source. An example wiring arrangement is shown in Annex A722, Figure A722.
For TN-S earthing systems (where the earth and neutral are separate throughout), the open PEN risk does not exist, and the earthing arrangement can be used directly for EV charging without additional measures. However, TN-S supplies are less common in the UK — most domestic supplies are TN-C-S (PME).
Elec-Mate's EV charger certificate template includes the O-PEN verification checklist from the IET CoP.
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Cable sizing for EV charger circuits follows the standard BS 7671 procedure but with particular attention to cable run lengths (which are often longer than typical domestic circuits) and the continuous nature of the load (EV charging is a continuous duty, not an intermittent load).
A 7 kW charger draws 32 A continuously. This means the cable must be rated for at least 32 A with all applicable correction factors applied — grouping, ambient temperature, thermal insulation, and installation method. The most common cable type for domestic EV installations is 6 mm² SWA (steel wire armoured), which provides mechanical protection for buried or surface-mounted runs. Per BS 7671 Table 4D4A, a 6 mm² 3-core XLPE (90 °C) armoured cable clipped direct (Method C) has a current-carrying capacity of 47 A at reference conditions — note that the 41 A figure sometimes quoted comes from Table 4D1A, which applies to flat PVC twin-and-earth cable, not SWA. All applicable correction factors (ambient temperature, grouping, soil thermal resistivity) must be applied before confirming 6 mm² SWA is adequate for the 32 A continuous EV load.
Voltage drop is frequently the limiting factor for EV charger cable sizing because of the long cable runs involved — the charger is often mounted on the side of a garage or at the end of a driveway, 20 to 40 metres from the consumer unit. Use the voltage drop calculator to verify compliance with the 5% limit (11.5 V on a 230 V single-phase circuit).
The Electric Vehicles (Smart Charge Points) Regulations 2021, which came into force on 30 June 2022, make smart functionality a legal requirement for all private EV chargepoints sold or installed in the UK. The regulations apply to domestic and workplace chargers but not to public rapid chargers above 50 kW.
OCPP (Open Charge Point Protocol) is the industry-standard communication protocol for EV chargers. It allows chargers from different manufacturers to communicate with a central management system (CMS) for monitoring, billing, load management, and remote diagnostics. OCPP 1.6 is the most widely deployed version; OCPP 2.0.1 is the latest, adding features such as device management, improved security, and support for ISO 15118 (vehicle-to-charger communication for plug-and-charge).
For commercial installations with multiple chargers, OCPP connectivity is essential for load management, usage tracking, and billing. The IET CoP recommends that electricians ensure the charger has network connectivity (Wi-Fi, Ethernet, or 4G) and that the OCPP back-end system is configured and tested during commissioning.
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Start free trialEV charger circuits require specific protection devices that may differ from standard domestic circuits. The key considerations are:
The choice between Type A and Type B RCD is one of the most common questions on EV installations. Type B RCDs are significantly more expensive (often over £200 compared to £30 for a Type A). Most reputable EV charger manufacturers now include a built-in DC residual current monitoring device (RCMU) that detects DC fault currents above 6 mA and disconnects the supply. When this is present, the installation manual will specify that only a Type A RCD is required upstream.
Installing an EV charger is notifiable work under Part P of the Building Regulations (Approved Document P) because it involves adding a new circuit. The following documentation is required:
Alongside Part P notification, electricians working on new dwellings and major renovations must also consider Approved Document S (Infrastructure for the Charging of Electric Vehicles). Part S requires EV charging infrastructure — cable containment and, in some cases, charge points — to be installed as part of the building work. It applies to new residential buildings with associated parking and to existing residential buildings undergoing major renovation where parking is provided. This is a distinct legal requirement from Part P and is noted in the On-Site Guide (OSG) as a cross-discipline consideration for electrical installers.
Elec-Mate streamlines the entire EV charger installation workflow — from initial load assessment through to certificate delivery and invoicing. Here is how the app supports each stage:
Enter the charger power, cable type, and run length. Elec-Mate calculates the minimum cable size with all correction factors applied and verifies voltage drop compliance. Works for both single-phase (7 kW) and three-phase (22 kW) chargers.
Dedicated EV installation certificate template with the IET CoP checklist built in. Covers earthing verification, O-PEN protection details, load management settings, and full test results. Exports as a professional PDF.
5th edition CoP for EV charging installations. BS 7671:2018+A4:2026 compliant guidance on cable sizing, load assessment, and earthing. Download now.
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