BS 7671 Amendment 4: EV Charging in Flats

EV charging in multi-dwelling buildings — flats, apartments, and mixed-use developments — is one of the most complex areas of EV infrastructure design. Building Regulations Part S requires EV charge point provision in new residential buildings, and Amendment 4 provides the BS 7671 framework for implementing these requirements safely in shared-supply environments.

The fundamental challenge is supply arrangement. In a block of flats, each dwelling typically has its own consumer unit and energy meter. EV charging can be supplied from either the individual dwelling supply or a communal (landlord) supply. Amendment 4 addresses both arrangements.

For individual dwelling supply: the EV circuit runs from the flat's consumer unit, through common areas, to the parking space. Amendment 4 requires that the cable route through common areas must use fire-resistant cable (LSZH minimum, fire-resistant per building fire strategy for enclosed routes). The circuit must have its own dedicated protective device in the dwelling consumer unit, and a local isolator must be provided at the parking space. Critically, the cable is part of the dwelling's fixed installation and must be included in the periodic inspection of that dwelling.

For communal supply: a dedicated EV distribution board is supplied from the landlord's incoming supply, with individual metered circuits to each parking space. Amendment 4 specifies that each EVSE must be individually metered and individually RCD-protected. The communal EV distribution board must incorporate load management to prevent overloading the communal supply. The freeholder or management company is responsible for the installation's periodic inspection.

Earthing in multi-dwelling EV installations requires particular attention. The parking area may be remote from the building's main earthing terminal, and PME earthing concerns (open-PEN conductor) apply to each EVSE. Amendment 4 requires that each EVSE location has an earth fault loop impedance within the limits of the protective device, verified at the EVSE location rather than the distribution board.

Accessibility and cable management in shared car parks are addressed. Amendment 4 requires that EV cable routes do not obstruct pedestrian access, do not present trip hazards, and are mechanically protected where subject to vehicle impact. Cables installed at low level must be protected to withstand at least IP4X and IK08 impact resistance.

ECalPro's EV Charging Calculator supports multi-dwelling EV designs per Amendment 4, including communal load management, individual circuit sizing, and earth fault loop impedance verification at the EVSE location.