ICCB on Mode 2 leads

What a Mode 2 in-cable control and protection device does, and what remains the responsibility of the socket and installation.

The box built into a portable Mode 2 EV charging lead is commonly called an ICCB, or in-cable control box. The standards term is in-cable control and protection device, abbreviated to IC-CPD.

It sits between the supply plug and the vehicle connector. It provides the control-pilot function and specified protective functions so a compatible vehicle can charge from a suitable socket. It does not turn any convenient household outlet into the equivalent of a properly designed fixed chargepoint.

The relevant product standard

IC-CPDs are covered by IEC 62752. As at 22 July 2026, the current international edition is IEC 62752:2024. It applies to portable Mode 2 devices that combine control and safety functions, including residual-current detection and disconnection.

The 2024 edition added a mandatory temperature-control device for the current-carrying parts in a household plug. An older lead may have been assessed to an earlier edition, so temperature sensing should be confirmed from the product declaration rather than assumed from the presence of a control box.

What the device does

Depending on its declared design, an IC-CPD can:

establish control-pilot communication with the vehicle
prevent energisation before a valid connection state
advertise the permitted charging current
detect specified residual-current conditions
check protective-conductor conditions required by its design
disconnect for detected faults or excessive plug temperature
provide status and diagnostic indications

Exact residual-current characteristics, self-test behaviour, temperature response and restart sequence belong to the product. Do not copy thresholds or indicator meanings from another lead.

What it does not prove

The control box cannot see every problem in the fixed installation. In particular, its presence does not establish that:

the socket contacts are tight and undamaged
the final circuit is suitable for a sustained charging load
upstream RCD protection is the correct type and coordinates with the device
the earthing arrangement is suitable for charging a vehicle outdoors
open-PEN protection is present where the design requires it
an extension lead or adaptor is safe
the socket is protected from water, impact or unauthorised use

Those are installation and use questions. They require the socket, circuit, protective devices, supply and charging location to be considered together.

Why an ordinary socket needs care

Vehicle charging can hold a substantial load for much longer than many ordinary plug-in appliances. A worn or loose socket contact creates resistance, and sustained current turns that resistance into heat. A plug-temperature sensor can disconnect after heating is detected, but it cannot repair a poor connection or confirm the wiring behind the socket.

Electrical Safety First recommends a dedicated home chargepoint as the safer and more convenient regular arrangement. If Mode 2 charging is used, follow the vehicle and IC-CPD instructions and have the intended socket and circuit assessed where there is any doubt.

Do not use a domestic extension lead or multiway adaptor. Do not run a lead through standing water, a closed door or window, or a route where it can be crushed. If the socket, plug or cable becomes unusually hot, discoloured or smells burnt, stop using it and have the cause investigated.

RCD and earthing context

EV power electronics can produce residual currents that ordinary assumptions about appliance circuits do not cover. The fixed installation needs the RCD arrangement required by BS 7671 Section 722 and the charging equipment’s instructions. The functions inside an IC-CPD must be coordinated with, not casually substituted for, upstream protection.

Likewise, PME and open-PEN risk is an installation issue. Some portable products may include additional protective functions, while others do not. Never infer open-PEN protection from the words ICCB, RCD or earth monitor. Check the declared function and whether the overall arrangement is acceptable for the supply and vehicle location.

Safe use and fault response

Before each use, check the supply plug, control box, cable and vehicle connector. The control box should be supported as instructed rather than hanging by the plug or lying where it can be driven over. Keep ventilation openings clear if the product has them.

Do not use the lead if:

the enclosure, plug, cable or strain relief is damaged
contacts are burnt, loose or contaminated
the device fails its prescribed self-test
it repeatedly trips or reports an unknown fault
it has been immersed or subjected to impact outside its rating
the product’s rating or conformity information cannot be identified

A repeated trip is a protective event to investigate, not an inconvenience to bypass. Do not change to a higher current, defeat the earth connection or repeatedly reset the device to force a session.

Smart and non-smart Mode 2 leads

The Great Britain smart-charge-point regulations distinguish a smart cable, which is itself a chargepoint able to send and receive information, from a non-smart cable. A basic IC-CPD may therefore fall outside the smart-device requirements, while an app-connected smart cable may fall within them.

That regulatory distinction does not rank their electrical safety. Both still need appropriate product evidence and a suitable supply arrangement.

When a fixed chargepoint is the better answer

For regular charging, a fixed Mode 3 chargepoint provides a dedicated circuit, designed protection, cable management and options such as dynamic load control. It also avoids relying on a general-purpose plug and socket for every long session.

Keep a Mode 2 lead as a useful portable or contingency tool if the vehicle manufacturer permits it, but plan around where it can be connected safely rather than assuming a socket will always be available.