What RCD protection does an EV charge point need?

The practical question is where the DC protection sits. If the charger has built-in DC fault current detection to 6mA, a Type A RCD rated at 30mA is sufficient¹. Where protection against DC residual current is provided in the charging equipment, a Type A or Type F RCD can be used². Where it is not, Regulation 722.531.3.101 of BS 7671:2018+A2 points to a Type B device².

This matters for household energy independence because the charge point is the one part of an EV setup that stays inside the home's own electrical installation. The car can be charged from a home solar array or a home battery, but the safety device protecting that circuit is fixed at installation and cannot be upgraded by firmware. What follows is what the Wiring Regulations require, what the charger makers build in, and what older wiring adds to the job.

What Regulation 722.531.3 requires for EV charging circuits

Section 722 of BS 7671 sets the requirements for electric vehicle charging installations¹. Regulation 722.531.3 requires RCD protection for EV charging circuits, and the charging point must be protected by its own RCD of at least Type A¹. The requirement applies to the socket-outlet or connector, not necessarily to the circuit supplying the charging equipment². That distinction is why a charger with an integral device can satisfy the rule without a second RCD at the consumer unit.

Two further rules shape the circuit. Each EV charging point should be supplied by its own dedicated final circuit, with a separate MCB or RCBO at the distribution board for each charger and no other loads sharing it¹. Regulation 722.312.2.1 adds that on TN systems the circuit supplying EV charging equipment must not include a PEN conductor¹. That is the reason PEN fault protection appears alongside RCD protection in charger specifications and in local authority guidance.

The regulation has been tightened over time. BS 7671:2018 Section 722 now contains further requirements for both Type A and Type B RCDs to take account of DC fault current³. An RCD associated with an EV charging installation should be tested in accordance with BS 7671:2018+Amd1:2020, Regulation 643.8⁴. All EV charging installations must continue to comply with the requirements of BS 7671, the Wiring Regulations governing them⁵.

For a household, the effect is that the charge point is a separately protected circuit rather than an extra load hung off an existing way. That is a safety gain and a small independence gain: a fault on the car circuit does not take the house down with it, and the circuit can be isolated on its own.

RCD types explained: Type A, Type F and Type B

Regulation 722.531.3.101 requires the charging point to be protected individually by an RCD of Type A, Type F or Type B². The three differ in what residual current they can tolerate before their ability to detect a fault is compromised.

Type A devices are designed and tested to tolerate moderate levels of DC residual current, up to 6mA⁶. Type F devices tolerate varying levels of DC residual current above 10mA, and are also suitable for the addition of plug-in solar on the circuits they protect⁶. Type B devices respond to smooth DC residual current that a Type A device may not detect, which is why they are specified where the charger provides no DC protection of its own¹.

A single-phase charger on a dedicated circuit takes a Type A or Type B RCD depending on the charger specification¹. The choice is not a preference: it follows from whether the wallbox detects DC fault current itself. A Type AC RCD must not be used for EV charging circuits at all¹.

DC fault current protection: RCD-DD to BS IEC 62955 or built into the charger

An RDC-DD is a residual direct current detecting device. BS EN 62955:2018 provides requirements for RDC-DDs to be used for Mode 3 charging of electric vehicles². The same standard is written as BS IEC 62955, and a device complying with it performs the DC detection function that would otherwise fall to a Type B RCD.

Where the equipment includes a built-in RDC-DD to BS IEC 62955:2018, a Type A RCD is permitted on the circuit¹. For Mode 3 charging, a Type A or Type F RCD is required where protection against DC residual current in the form of an RDC-DD is provided within the charging equipment². Where no protection against DC residual current is provided in the equipment, Regulation 722.531.3.101 of BS 7671:2018+A2 requires a Type B RCD².

Several UK wallboxes now carry the device internally. The Easee Charge Pro has an integrated RCD Type A 30mA AC to IEC 60947-2 and a 6mA residual direct current detecting device complying with IEC 62955⁷. The SolarEdge ONE EV Charger EVN22B lists an RDC-DD of 6mA DC according to IEC 62955⁸. DEFA Power Up models list RCD-DD 6mA DC in accordance with IEC 62955⁹. The Smappee EV Wall integrates 6mA DC and 30mA RCD type A protection¹¹.

The consequence for a household is that the DC protection may be a sealed component inside the charger rather than a device in the consumer unit. It is tested as part of the installation and cannot be inspected or replaced in the same way as a board-mounted device.

When a Type A RCD with 6mA DC protection is enough

A Type A RCD is sufficient where the charger detects DC fault current itself. If the EV charger has built-in DC fault current detection to 6mA, a Type A RCD rated at 30mA is sufficient¹. The RCD must be rated at 30mA for additional protection¹.

The 6mA figure is the threshold at which a Type A device's ability to detect an AC fault can be affected by DC residual current. A Type A RCD is designed and tested to tolerate moderate levels of DC residual current, up to 6mA⁶. Above that, the device may not trip as intended, which is why a charger without its own DC detection needs a Type B RCD instead¹.

In practice this is the common arrangement in current UK wallboxes. The Growatt Smart EV Charger Solution lists Type A RCD plus 6mA DC fault current protection, alongside overload, over and under voltage, lightning, over temperature, earth leakage, short circuit and fault current protection¹³. The Enphase IQ EV Charger 2 lists 6mA DC residual current protection as an RCD-DD¹⁴. A Project EV unit lists an RCBO with Type A plus 6mA DC fault current protection¹⁵. The Rolec UltraCharge 40 has built-in 30mA Type A RCD protection¹⁶.

The pattern is that the wallbox carries the DC detection and the circuit carries a Type A device, or the two are combined in one unit. For the household, the practical point is that the specification sheet, not the age of the consumer unit, determines whether a Type B device is needed.

Do I need a separate RCD if my charger has built-in DC fault protection?

The DC element is covered by the charger, but RCD protection of the charging point is still required. Where protection against DC residual current is provided in the charging equipment, a Type A or Type F RCD can be used². The requirement for RCD protection applies to the socket-outlet or connector and not the circuit supplying the equipment².

Some chargers integrate the RCD as well as the DC detection. The Easee Charge lists integrated earth fault protection¹⁷. The Sync Energy EV Wall Charger 2 (Tethered) is described as offering quick installation with RCD and PEN protection¹⁸. Where the charger provides both, the installer confirms what remains to be provided at the distribution board, which is usually the overcurrent device and the isolation.

PEN fault protection is a separate matter from RCD type and often appears in the same specification. Most local authorities specify that households install a dedicated EV charger with protective earth neutral fault protection¹⁹. The Energy Saving Trust states that where a cross-pavement solution is used, a dedicated EV charger with PEN fault protection must be installed¹⁹. Regulation 722.312.2.1 is the underlying rule: on TN systems the circuit supplying EV charging equipment must not include a PEN conductor¹.

Can my existing consumer unit RCD cover the EV charger circuit?

Usually not on its own. The charging point needs its own RCD of at least Type A, and a dedicated final circuit with a separate MCB or RCBO at the distribution board for each charger, with no other loads sharing it¹. A shared RCD covering several circuits does not meet the expectation that the charging point is protected individually.

Consumer unit design affects how easily that is achieved. High integrity units provide either circuit breakers or the combined RCD and circuit breaker protection of an RCBO for each connected circuit, without combining circuits under a single RCD²⁰. An RCD main switch unit comes with an RCD main switch that can safely isolate the entire electrical supply of the home, with individual circuit breakers protecting each connected circuit²⁰. The first arrangement isolates faults to one circuit; the second protects the installation as a whole.

An RCD in the consumer unit protects from electric shocks if a product is faulty²¹. That general function is not the same as the specific requirement for the charging point. Where a circuit has no RCD protection, the general advice for portable equipment is to use an RCD plug on the socket where the product is plugged in²¹. That is not a route to compliance for a fixed EV charge point, which is a dedicated circuit rather than a plug-in appliance.

For a household, the practical outcome is often a spare way in the consumer unit, an RCBO or RCD plus MCB for the charger, and a separate device inside the wallbox for DC detection. E.ON Next states that its quotes include core safety protections such as surge protection and RCD or RCBO protection where required²³.

Installation in older homes: what the wiring adds to the RCD requirement

Older wiring does not change the RCD rule, but it changes how much work the rule implies. Key requirements for an EV charger installation include a dedicated circuit, RCD protection and proper earthing arrangements²⁴. Where the existing board cannot provide those, the installation grows.

The warning signs are well documented. A wooden backing to the consumer unit is a sign of a vintage model, and a board with no test button has no RCD protection²⁵. Nuisance tripping is another indicator that the existing arrangement is not suited to the new load²⁵. The Institution of Engineering and Technology has warned that some older homes may have wiring or protection devices not designed for electricity flowing back into a circuit, and that older consumer units may contain RCDs that may not trip properly, meaning they do not offer shock protection when a fault occurs²⁶.

The RCD for the charging point is likely to be installed within the charging equipment⁴. That reduces what the consumer unit must provide, but it does not remove the need for a dedicated circuit, correct earthing and a protective device at the board. Where the existing installation cannot support that, the work is a consumer unit change or an additional enclosure rather than a simple extra way.

Two further points sit outside the electrical rules but affect the job. Installing a home charger is classified as development, and it is up to the householder to ensure the correct permissions are in place²⁶. In England, home EV chargers, public charging points and business installations now fall under permitted development rights⁵. All EV charging installations must continue to comply with BS 7671 regardless⁵.

For energy independence, the RCD arrangement is the fixed part of the setup. A household that later adds solar, a battery or a smart tariff is changing how the car is supplied, not how the circuit is protected. The protection is set once, at installation, and the evidence for it is the certificate the installer issues.