Three-Phase EV Supply: 22kW Chargepoint Installation and Supply Requirements
Quick Answer: A 22kW EV chargepoint requires a three-phase 400V supply (32A per phase, 3× single-phase, L1+L2+L3+N+E). Most UK residential properties have single-phase only; three-phase is common in larger detached houses, rural properties, and commercial premises. Installation requires a three-phase RCBO or three-pole MCB plus RCD, 4mm² or 6mm² five-core cable, and a 22kW-capable chargepoint from the OZEV approved list. Not all EVs can charge at 22kW — check the vehicle's onboard charger specification before recommending the upgrade.
Summary
22kW AC charging is the fastest AC charge rate available on public or semi-public charge networks, and the maximum permitted for domestic AC installation under current regulations. At 22kW, a vehicle with a 77kWh battery charges from 20% to 80% in approximately 2.5 hours — roughly three times faster than a 7.4kW single-phase unit.
However, 22kW is only accessible to customers who already have a three-phase supply, and only for EVs equipped with a three-phase onboard charger (OBC). Many popular EVs — including the Nissan Leaf, base Tesla Model 3, and most base-spec Korean EVs — have single-phase OBCs limited to 7.4kW regardless of chargepoint output. Before specifying a 22kW installation, the vehicle's AC charging limit must be confirmed.
For electricians, three-phase EV installations follow the same principles as single-phase but with added complexity: a five-core cable, three-phase protection, three-phase load management, and a higher-rated chargepoint. This article covers the supply requirements, installation, and vehicle compatibility.
Key Facts
- Three-phase 400V — UK commercial three-phase supply: 230V phase-to-neutral × √3 = 400V phase-to-phase
- 22kW chargepoint power — 32A × 400V × √3 = 22,170W (~22kW); three-phase 32A per phase
- 16A per phase option — some 22kW chargepoints are configurable to 11kW (16A per phase); useful if supply capacity is limited
- Five-core cable — L1, L2, L3, Neutral, Earth; minimum 4mm² for short runs, 6mm² for runs over 15–20m
- Three-phase RCBO — Type B three-phase RCBO preferred; or three-pole MCB plus a separate 30mA RCD
- PME earthing — same PME earth fault concern as single-phase installs; TT electrode or PEN fault detection required
- Three-phase OBC — only EVs with a three-phase OBC can charge at 22kW; single-phase OBC vehicles max out at 7.4kW even on a 22kW chargepoint
- Renault Zoe (50kW AC) — the most common three-phase OBC vehicle in the UK; charges at 22kW AC
- IEC 62196 Type 2 — the three-phase charging uses the same Type 2 connector as single-phase; the chargepoint and vehicle negotiate the mode and current via the control pilot signal
- Three-phase load management — CT clamp on all three phases required; load management must account for all three phases independently
- Maximum domestic AC — UK Building Regulations and DNO distribution codes: 22kW is the practical maximum for domestic AC EV charging without substantial infrastructure upgrade
- DNO notification — installations above certain thresholds (typically G99/G100 for generation; check DNO guidance for EV loads) may require DNO notification; confirm with the local DNO for supply sizes above 50A per phase
Quick Reference Table: Single-Phase vs Three-Phase Comparison
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Try squote free →| Parameter | Single-Phase 7.4kW | Three-Phase 22kW |
|---|---|---|
| Voltage | 230V L-N | 400V L-L (230V per phase) |
| Current | 32A single phase | 32A per phase × 3 |
| Cable | 6mm² twin and earth | 5-core 4–6mm² |
| Protection | 32A RCBO (Type B) | 3-phase RCBO or 3-pole MCB + RCD |
| Charging speed | ~25–30 miles/hr | ~75–80 miles/hr |
| Vehicle compatibility | All EVs | Only 3-phase OBC vehicles |
| Relative cost | Standard | ~50–75% more |
| OZEV grant | Yes (domestic) | Yes if OZEV-approved model |
| Typical use | Domestic | Commercial; 3-phase domestic |
Detailed Guidance
Confirming the Three-Phase Supply
Before designing a three-phase EV installation, confirm the supply:
Step 1: Locate the cut-out A three-phase supply has four fuses (or three fuses + neutral link) in the DNO cut-out, or a single three-phase unit. Single-phase cut-outs have one fuse and a neutral.
Step 2: Check the meter Three-phase meters show L1, L2, L3 voltage readings (all approximately 230V) or a phase-to-phase reading (approximately 400V). A single-phase meter shows one voltage only.
Step 3: Check the consumer unit (distribution board) A three-phase consumer unit has a main switch or incomer that connects three live bars. If only one live bar is present, the supply is single-phase.
If three-phase is not present: Three-phase supply upgrades require a DNO application. For most residential properties, the DNO will quote for the infrastructure upgrade. This typically costs £2,000–£10,000+ and takes 3–6 months for approval and connection. It is rarely worthwhile for EV charging alone unless the customer has other three-phase loads (workshop, large heat pump) to justify the upgrade.
Vehicle Compatibility Check
The vehicle's OBC (onboard AC/DC converter) limits the maximum AC charge rate regardless of the chargepoint output.
Three-phase OBC vehicles (can use 22kW AC):
- Renault Zoe (ZE40/ZE50) — up to 22kW (some earlier versions limited to 43kW, others 22kW; confirm by variant)
- Peugeot e-208 — 11kW three-phase standard
- Vauxhall Mokka-e / Corsa-e — 11kW three-phase
- Kia EV6 / Hyundai IONIQ 5 — 11kW three-phase
- Porsche Taycan — 11kW standard, 22kW as option
- Mercedes EQS — 11kW or 22kW (variant-dependent)
- BMW i4/iX — 11kW three-phase
Single-phase OBC vehicles (limited to ~7.4kW regardless of chargepoint):
- Nissan Leaf (all variants) — 6.6kW or 3.6kW single-phase
- Tesla Model 3/Y (base/SR+) — 7.4kW single-phase; Long Range/Performance variants: 11kW three-phase
- VW ID.3/ID.4 (most variants) — 11kW three-phase (confirm; some early UK variants had 7.4kW single-phase OBC)
- Toyota bZ4X — 11kW three-phase
How to confirm: Check the manufacturer's specification for "AC charge rate" or "onboard charger." This figure is the vehicle's maximum, not the cable or chargepoint's limit.
Circuit Design for a 22kW Three-Phase Chargepoint
Protection device:
- Option 1 (preferred): Three-phase Type B RCBO — provides overload, short circuit, and 30mA residual current protection in one device; takes 3 ways in the consumer unit
- Option 2: Three-pole Type B MCB (32A per pole) + separate 30mA Type A or Type F RCD on the circuit
Type B trip characteristic is required to accommodate the DC components in the chargepoint power supply (same reason as single-phase — see bs 7671 ev wiring requirements).
Cable sizing:
- 4mm² five-core (L1, L2, L3, N, E) — adequate for runs up to approximately 15m
- 6mm² five-core — for runs of 15–40m; always preferred for outdoor/exposed routes
- Armoured cable (SWA) — for underground or external conduit runs; 6mm² five-core SWA is standard for post-mounted chargepoints
Cable route: Same considerations as single-phase: avoid heat sources, maintain separation from other services, run in conduit where surface-mounted, bury at correct depth with cable marking tape if underground.
PME earthing: Identical requirement to single-phase. For PME supplies, install a TT earth electrode or a PEN fault detector. Do not connect the chargepoint earth terminal directly to a PME earth. See pme earthing ev charging.
Three-Phase Load Management
With a 22kW chargepoint drawing up to 32A per phase, three-phase load management requires monitoring all three phases:
- Fit a CT clamp on each of the three live incomers (L1, L2, L3)
- Configure the chargepoint with the per-phase fuse rating (e.g., 63A per phase for a commercial supply; 32A per phase for a smaller three-phase domestic supply)
- The chargepoint monitors the most loaded phase and reduces its charge current to protect that phase
- For a balanced three-phase chargepoint, reducing charge current reduces it equally on all three phases
See ct clamp load management for CT clamp installation details.
Commissioning a Three-Phase Chargepoint
Commissioning follows the same procedure as single-phase (EIC, smart charging setup, Wi-Fi connection) with the addition of:
- Confirming three-phase voltage at the chargepoint terminals (approximately 230V phase-to-neutral; approximately 400V phase-to-phase)
- Confirming the chargepoint recognises three-phase operation in its commissioning menu
- Setting the per-phase current limit in the chargepoint app (32A maximum; configure lower if supply headroom requires it)
- Running a test charge and confirming the vehicle is charging at three-phase rate (the vehicle's dashboard or charging app should confirm kW input)
Note: If a single-phase vehicle (Nissan Leaf, etc.) is connected to a three-phase chargepoint, it will charge at single-phase rate only (typically 6.6kW). This is expected behaviour — the chargepoint will show reduced current on L1 only. This is not a fault.
When 11kW Is a Better Choice Than 22kW
11kW (16A per phase, three-phase) is a common intermediate option:
- Most three-phase OBC vehicles accept 11kW as their maximum (Peugeot e-208, Vauxhall Corsa-e, VW ID.3 standard)
- Lower cable sizing possible (4mm² vs 6mm² for long runs)
- Lower protection rating (16A per pole vs 32A)
- Less supply headroom required
- Still ~3× faster than 7.4kW single-phase
If the customer's vehicle is limited to 11kW, installing a 22kW chargepoint provides no benefit. A 22kW-capable chargepoint configured to 11kW output is fine, but costs more than an 11kW unit.
Frequently Asked Questions
My customer has a three-phase supply but doesn't have a three-phase OBC vehicle. Is 22kW worth it?
No. The vehicle's OBC is the bottleneck. If the vehicle's maximum AC charge rate is 7.4kW, a 22kW chargepoint will charge at 7.4kW. The additional cost of the three-phase circuit and chargepoint is wasted. Install a standard 7.4kW single-phase unit instead.
Can a 22kW chargepoint also work on a single-phase supply?
No. 22kW requires three phases. Some chargepoints are "three-phase capable" but can also run at single-phase 7.4kW on a single-phase supply — but this gives no advantage over a dedicated 7.4kW unit and typically costs more. Specify the correct chargepoint for the available supply.
Does a 22kW chargepoint qualify for the OZEV grant?
Yes, provided the model is on the OZEV approved list. The grant amount (where applicable) is the same regardless of chargepoint power rating. Commercial and workplace grants (OZEV EVCP/EV infrastructure grant) also apply to three-phase units.
How much more does a three-phase install cost than a single-phase?
Typically 40–75% more in materials and labour. Additional costs: five-core SWA cable vs twin-and-earth, three-phase protection device, higher-rated chargepoint hardware. On a typical residential installation, a single-phase install might cost £800–£1,200 in materials; a three-phase install £1,200–£1,800, plus the same labour.
Regulations & Standards
BS 7671:2018+A2:2022 — Chapter 722: all Mode 3 chargepoints including three-phase
IEC 62196 — Type 2 connector and three-phase charging protocol
IEC 61851 — EV conductive charging system; Mode 3 definitions
Electric Vehicles (Smart Charge Points) Regulations 2021 (SI 2021/1467) — smart charging requirements apply to three-phase units equally
G99 / G100 — DNO connection regulations for generation; check with local DNO for large EV load connection notification requirements
IET Guidance Note 7 — EV Charging — three-phase installation guidance
OZEV Approved Product List — confirmed three-phase models
Zap-Map AC charging guide — vehicle OBC compatibility reference
ev charger installation types — Mode 3 single and three-phase overview
bs 7671 ev wiring requirements — Chapter 722 circuit design
pme earthing ev charging — earthing for three-phase EV installs
ct clamp load management — three-phase load management installation
ev charging commercial premises — three-phase installs in commercial settings