EV charger protection guide: choose Type A/B RCD and RCBO, size the MCB and contactor, and wire Type 2 connectors to IEC 60364-7-722.
Unlike a household socket, an EV charging station (EVSE) carries continuous high current and brings the vehicle's charging circuit within reach of the user. International wiring rules — IEC 60364-7-722, BS 7671 Section 722 and NEC Article 625 — therefore require a specific stack of protective devices that a standard consumer unit does not provide. Specifying the right combination at the design stage avoids costly rework and, more importantly, prevents electric shock and fire.
Direct current fault current is the defining hazard of EV charging. A conventional AC RCD cannot detect smooth DC residuals, so the rules mandate Type A RCDs (for Mode 3 wallboxes with an integrated DC monitoring device) or Type B RCDs (full AC plus pulsating and smooth DC). For permanent installations the preferred device is an RCBO — a residual-current breaker with integrated overcurrent protection in a single module — which saves valuable DIN-rail space in a crowded charger enclosure.
| Device | Detects | Typical application |
|---|---|---|
| Type A RCD / RCBO | AC + pulsating DC | Mode 3 wallboxes with DCIM |
| Type B RCD / RCBO | AC + pulsating + smooth DC | Three-phase 22 kW stations |
| MCB (Type B / C) | Overload and short circuit | Upstream cable protection |
| AC contactor | Load switching | Remote enable and CP control |
The upstream miniature circuit breaker (MCB) must protect the supply cable, not the charger itself. A 7.4 kW single-phase station draws about 32 A, so a 40 A Type B or C MCB on 6 mm² copper cable is typical; a 22 kW three-phase unit needs a 32–40 A three-phase breaker. Always follow the charger manufacturer's maximum rated current and the local derating curve for cables bundled inside a sealed enclosure.
Every compliant charger switches its output through an AC contactor that the control board commands via the proximity (PP) and control pilot (CP) lines. The contactor must carry the full charge current under AC-3 duty and, for three-phase supplies, break all poles including neutral. A 40 A or 63 A AC contactor with a 230 V AC coil is the workhorse here; an auxiliary contact feeds the contactor state back to the controller for a safe interlock.
IEC 62196 Type 2 (Mennekes) connectors dominate Europe and most export markets. Beyond the power conductors, the CP and PP signalling lines must be run in the same cable and terminated on the correct control board. Never extend the CP line with ordinary mains cable — its low-current signal is sensitive to noise and must keep its characteristic impedance. Use IP-rated cable glands and proper strain relief to keep the inlet sealed against the weather.
Wallboxes and column mounts live outdoors, so the enclosure should be at least IP54, with IP65 preferred, in UV-stable polymer or coated steel. Mount the RCBO and contactor on a DIN rail inside, leaving clearance for heat dissipation. A vented, fan-assisted cabinet helps on 22 kW units exposed to direct sun.
When sourcing from a low-voltage catalogue, confirm each item carries the right certificate — CE/CB marks, IEC 61008 or IEC 61009 for RCBOs, and IEC 60947-4 for contactors — matches the charge current, and ships with its DIN-rail accessories. Buying the RCBO, MCB and contactor as a coordinated set from one supplier simplifies warranty claims and on-site commissioning.
For a Mode 3 wallbox that integrates a DC monitoring device (DCIM) compliant with IEC 62955, a Type A RCBO is generally accepted in many markets. For three-phase chargers or any location where smooth DC faults can occur, a Type B RCD is required. Check your local wiring regulation before specifying.
A standard RCD provides the residual-current function, but you still need separate overcurrent protection. An RCBO combines both in a single 18 mm module, saving DIN-rail space and reducing wiring errors in a compact charger enclosure.
A 7.4 kW single-phase station draws roughly 32 A. Choose an AC-3 contactor rated at least 40 A — 63 A gives comfortable margin — with a 230 V AC coil that matches the control supply.
The CP line carries the signalling between car and charger that enables charging only when safely connected and that ramps current up and down. It is a low-current circuit and must be installed exactly as specified, never with ordinary mains cable, or the charger may fail to start or misread the connection.
A minimum of IP54 is required, with IP65 preferred for exposed locations. The material should be UV-stable polymer or coated steel, and all cable entries must use IP-rated glands to keep the interior dry.
Send the ratings, dimensions and quantities you are working to and we will confirm the closest match from the ELEHPD catalogue, the compliance documents available for it and the lead time. OEM branding, private model numbering and buyer-specific cartons are available on qualified volumes.