IEC 61851 charging modes (Mode 1-4) for electric vehicles — overview and practical differences

The guide on the Control Pilot signal covers the voltage levels and the PWM duty cycle of the CP signal as used in Mode 3 charging. This article covers a level up: the distinction between the four charging modes defined by IEC 61851-1, and why not every mode is suitable (or permitted) for a fixed charge point.

The four charging modes

Mode	Connection	Control/protection	Typical application
Mode 1	Direct connection to an ordinary socket-outlet	No control or protection device in the charging cable itself — the installation itself must provide the protection	Light two-wheelers; restricted or not permitted for cars in some countries
Mode 2	Ordinary socket-outlet, with an in-cable control/protection device (IC-CPD) in the charging cable itself	Control Pilot communication and residual-current protection built into the cable	Occasional charging on an existing socket-outlet, using the manufacturer's supplied "emergency cable"
Mode 3	Fixed charge point (wallbox/charging station) with a fixed connection to the installation	Control Pilot communication and protection built into the charge point itself	The standard solution for fixed charge points at home, at work and in public
Mode 4	DC fast charging via an external charger	Power electronics (rectification) located outside the vehicle, in the charging infrastructure itself	Public DC fast chargers along motorways and at charging hubs

Why Mode 3 is the standard choice for a fixed charge point

With Mode 3, the Control Pilot communication (see the CP signal guide for the 12V/9V/6V/3V voltage levels) and the residual-current protection are permanently built into the charge point itself — not into a loose, vulnerable in-cable box as with Mode 2. This makes Mode 3 the most robust and predictable solution for a permanently installed charge point, and the standard implementation for a NEN 1010 §722-compliant charging installation (see the §722 guide).

Mode 1 and Mode 2: why these are less suited to a fixed installation

With Mode 1, any form of communication or specific protection in the charging cable itself is absent — protection must come entirely from the fixed installation (the socket-outlet and its circuit), with the risk that an ordinary socket-outlet is not designed to continuously deliver the full power a vehicle may demand over a long period. In a number of countries, Mode 1 charging for cars is therefore restricted or not permitted.

Mode 2 adds a control and protection device into the charging cable itself (the IC-CPD, often recognisable as a thickened section in the cable), making it possible to charge safely on an ordinary socket-outlet — but this device then sits in a cable that is regularly coiled and uncoiled and exposed to mechanical wear, unlike the permanently mounted electronics of a Mode 3 charge point. Mode 2 is therefore mainly used as an occasional solution (the supplied "emergency cable"), not as a structural provision.

Mode 4: power electronics outside the vehicle

With Mode 4, rectification from AC to DC does not take place in the vehicle itself (as with Mode 1-3), but in the external charging infrastructure — the charger delivers DC directly to the vehicle's battery. This enables considerably higher charging power than is achievable with AC charging (Mode 1-3), and forms the basis of public DC fast chargers.

Practical relevance

When assessing a charging solution, first establish which mode applies before determining the installation requirements: a Mode 3 charge point requires a fixed NEN 1010 §722-compliant connection with the associated protection built into the charge point itself, while a Mode 2 solution on an existing socket-outlet has different, less structural requirements — and Mode 1 for car charging is in many cases unsuitable or not permitted.

Common mistakes

Confusing Mode 1 and Mode 2 — the crucial difference is the presence of a control/protection device in the charging cable itself (IC-CPD), which Mode 1 lacks and Mode 2 has.
Using a Mode 2 "emergency cable" as a structural fixed charging solution — the in-cable electronics of Mode 2 are designed for occasional use, not for continuous, daily loading like a fixed Mode 3 charge point.
Assuming every charge point is simply "Mode 3" without verifying that the communication and protection are actually built into the charge point itself.
Confusing Mode 4 (DC fast charging) with a high-power Mode 3 charge point — with Mode 4, rectification takes place outside the vehicle, requiring fundamentally different infrastructure than AC charging.