Part S EV Charging Infrastructure: New Dwellings, 7kW Socket Requirements and Cable Routing

Quick Answer: Approved Document S (Electric Vehicle Charging Points) applies to new residential buildings and buildings undergoing renovation. New dwellings with associated parking must have a 7kW EV charge point as standard. The charge point must comply with the Electric Vehicles (Smart Charge Points) Regulations 2021, meaning it must be smart-enabled. Cable routing (cable containment to the parking space) is required even where a charge point is not yet installed.

Summary

Approved Document S came into force in England on 15 June 2022. It implements requirements for EV charging infrastructure across new and renovated buildings, responding to the government's target to phase out new petrol and diesel car sales. For developers and builders, Part S adds a mandatory element to new residential projects and creates cable routing obligations for some renovation projects.

The requirement is not simply to install a socket — it mandates a specific type of smart charge point that can communicate with the grid, respond to time-of-use tariffs, and potentially support vehicle-to-grid (V2G) in future. This is the Electric Vehicles (Smart Charge Points) Regulations 2021 (EVCSR) requirement, which runs alongside Part S.

For electricians, Part S generates new work: charge point installation is notifiable work under Part P, and the specific requirements for EVSE (Electric Vehicle Supply Equipment) create technical considerations around earthing, circuit protection, cable sizing, and smart connectivity. Understanding both the building regulations trigger and the technical installation requirements is essential.

Key Facts

Quick Reference Table

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Building Type Part S Applies? Requirement Cable Containment
New dwelling with ≥1 parking space Yes 1× 7kW smart charge point Required if parking remote
New dwelling with no parking No None None
New non-residential building (≥10 spaces) Yes (at least 1 space) 1× charge point per 5 spaces; 1 per 5 EV-ready spaces Required for remaining spaces
Residential renovation (10% rule) Conditionally Per above if parking created/modified As above
Change of use to dwelling Possibly Check with BCO; AD S guidance As appropriate
Existing single dwelling (no works) No Not triggered by existing state N/A

Detailed Guidance

Part S Trigger Conditions

New residential buildings: Any new residential building that has associated parking must be fitted with a 7kW EV charge point per dwelling. "Associated parking" means:

If there are multiple dwellings each with allocated parking, each parking space needs a charge point.

Renovation trigger: The renovation trigger is more nuanced:

This means a standard domestic extension rarely triggers Part S (it does not create 10 parking spaces). Large residential developments undergoing refurbishment where the car park is being modified are more likely to be caught.

Standalone car parks: Car parks with ≥10 spaces being newly constructed: 1 charge point per 5 spaces minimum; remaining spaces must have cable containment ready for future installation.

Technical Requirements: 7kW Smart Charge Point

Charge point specification:

EVCSR 2021 requirements for smart charge points:

Approved products: MCS does not certify EV charge points. The Office for Product Safety and Standards (OPSS) enforces EVCSR. Suppliers sell into this market with self-declared compliance.

Earthing and Electrical Safety

EV charge point installation has specific electrical safety considerations, particularly related to the earthing arrangement of the premises.

TN-C-S (PME) supplies: Most UK domestic properties are supplied via TN-C-S (Protective Multiple Earthing). In a PME arrangement, the supply neutral and earth are combined at the DNO's earth point. If the PME earth becomes broken (open-circuit PEN conductor), the consumer's earthing conductors can become live at a dangerous voltage.

For EV charge points outdoors:

Compliant options for PME outdoor charge points:

  1. TT earthing at the charge point: Separate earth electrode at the charge point; disconnect from PME; this is the most robust solution
  2. RCD with PEN failure detection: Some EV chargers include a PEN fault detector that trips the EVSE if the PEN conductor becomes broken
  3. Separation from PME using an isolating transformer: Provides safety isolation; expensive

Standard domestic installation: In practice, most domestic 7kW installations use a TT earth electrode at the charge point with a 30mA RCD, and PEN fault protection is provided by the charge point's internal electronics. Always consult the charge point manufacturer's installation instructions and verify the earthing arrangement with the installer.

Circuit Design: Cable Sizing and Protection

Cable sizing for a 7kW charge point:

Consumer unit capacity:

DNO notification:

Cable Containment (Pre-wiring)

Where a charge point is not immediately installed but is required by Part S, cable containment must be provided. This means:

This provision allows the homeowner to install a charge point in future without significant building work.

Part P Notification for EV Charge Point Installation

Under Part P (Building Regulations, England and Wales), EV charge point installation is notifiable work:

Certificate: On completion, provide an Electrical Installation Certificate (EIC) and notify Building Control (via competent person scheme or direct).

Frequently Asked Questions

Does Part S apply to an existing house where I am adding a garage?

If you are building a new garage attached to an existing dwelling, Part S may apply as a new associated parking space is being created. Specifically, if the new garage is for a vehicle and serves the dwelling, you should check with your local Building Control Officer whether Part S is triggered. The safest approach is to include a 7kW charge point in the new garage as part of the works — the cost is modest relative to the garage construction.

Can I install a 3-pin socket for EV charging instead of a dedicated charge point?

No, where Part S requires a charge point. A 3-pin socket (Mode 2 charging, via a domestic extension lead or ICCB) is not compliant with the 7kW smart charge point requirement. Mode 2 charging from a domestic socket is also slower (max 3kW at 13A) and creates risk from sustained high current through a non-dedicated circuit. A dedicated 7kW Mode 3 charge point is the correct installation.

Our consumer unit is full — can we still comply with Part S?

Yes, but the consumer unit must be upgraded or a sub-board installed to accommodate the 32A RCBO for the charge point circuit. This is common on older properties. The consumer unit upgrade is notifiable work under Part P. Budget for this as part of the charge point installation quote.

Does Part S apply in Scotland?

Scotland has its own building standards under the Building (Scotland) Act 2003. Section 3.18 of the Scottish Building Standards covers electric vehicle charging provision, with requirements phased in from 2022. Check with the local authority building standards department for current requirements — the framework is similar to Part S but has some differences.

Regulations & Standards