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Commercial EV Dynamic Load Management & Curtailment Sizer

Avoid costly DNO network reinforcement and main cut-out fuse failure. This tool calculates available supply headroom, models dynamic curtailment waterfalls under peak building demand, enforces the IEC 61851-1 6A minimum pilot floor, and evaluates three-phase neutral conductor loading under single-phase charging diversity.

Statutory Regulation 722.311: Diversity may only be applied to electric vehicle charging equipment where an automated load management system is installed that monitors incomer demand and dynamically curtails charging current.

1. Building Supply & Baseline DemandMain Incomer Supply Capacity per PhaseUpstream DNO cut-out fuse or MCCB incomer rating.Building Baseline Peak Demand (Amps per Phase)Measured maximum demand from half-hourly data or max CT logging.Incomer Safety Margin / Headroom BufferCurtailment triggers when total site current reaches this threshold.

2. Connected EV FleetSingle-Phase 7.4 kW (32A @ 230V) Charge Points ConnectedEvenly balanced across phases L1, L2, L3 by the load controller.Three-Phase 22 kW (32A @ 400V) Charge Points ConnectedDraws 32A simultaneously across all three phases.Active Vehicles Simultaneously Requesting Full ChargeTotal EVs plugged in and actively communicating via CP pilot line.

3. DLM Controller ProtocolIEC 61851-1 Minimum Pilot Curtailment FloorVehicles receiving less than this current will be paused or queued.Dynamic Curtailment Mode

Dynamic Curtailment Telemetry

DLM Dynamic StatusCALCULATING...

Curtailed Cut-Out Threshold--

Building Peak Base Load--

Unconstrained Fleet Demand--

Active Bay Allocation

Allocated Current per Active Bay--

Effective Charging Speed--

Queue & Load Shedding State--

Estimated Neutral Current (Unbalanced)--

Evaluating DLM curtailment waterfall...

INCOMER CAPACITY UTILISATION0%

Base Load Allocated EV Safety Reserve

BS 7671 Section 722 Dynamic Load Management Formulation

BS 7671:2018+A4:2026 Section 722 & IET Code of Practice 5th Edition

AM2 PORTFOLIO & DESIGN AUDIT FORMATTRANSPARENT FIRST-PRINCIPLES MATHS

Scenario: 200A 3-phase commercial incomer, 10% safety buffer (180A trip limit), 110A baseline demand, 6 × 7.4 kW and 2 × 22 kW EV charge points (8 vehicles charging simultaneously):

Unconstrained Fleet Demand: 6 single-phase bays balanced across 3 phases = 2 bays/phase (64A) + 2 three-phase bays (64A) = 128A per phase.
Available EV Headroom: 180A - 110A = 70A per phase.
Dynamic Curtailment: Fleet demand (128A) exceeds available headroom (70A). The DLM controller proportionally curtails all active vehicles from 32A down to approx 17.5A per bay.
Statutory Safety: Total incomer load is maintained at exactly 180A, fully preventing upstream DNO fuse operation without cutting power to charging bays.

Earthing & PME Advisory (Regulation 722.411.4.1): For EV charging equipment connected to a PME (TN-C-S) supply, protective multiple earthing shall not be used for protective earthing of charge points located outdoors unless open-PEN detection devices complying with BS 7671:2018+A4:2026 Reg 722.411.4.1 are incorporated.

Statutory Standards: BS 7671:2018+A4:2026 Section 722.311 • IET Code of Practice 5th Edition • IEC 61851-1