What is Residual Current Device (RCD) in EV Chargers?

The rise of electric vehicles (EVs) has brought about the need for safe and reliable charging infrastructure. One important component of EV chargers is the Residual Current Device (RCD),

which plays a critical role in ensuring the safety of both the vehicle and the charging station.

In this article, we’ll take a closer look at RCD  in EV chargers, including their function, types,

and installation and maintenance best practices.

type a RCD

What is Residual Current Device(RCD) and how does it work?

An RCD is a device that detects electrical faults, such as ground faults or electric shock hazards, and interrupts the flow of electricity.

It monitors the current flowing through a circuit and compares it to the current returning through the neutral wire.

If there is a difference in current between the live and neutral wires, the RCD will trip and cut off the electricity supply.

get an electric shock

RCD in EV chargers

In the context of EV chargers, RCDs play a critical role in ensuring safe and reliable charging infrastructure.

They protect against ground faults, which can occur when there is a fault in the electrical system that causes current to flow through the ground instead of returning through the neutral wire.

Ground faults can be particularly dangerous in EV chargers due to the high voltage and current involved.

RCDs also protect against other risks associated with EV charging, such as water ingress and electrical arcing.

Water ingress can cause short circuits and other electrical problems, while electrical arcing can cause high temperatures and damage to electrical components.

If an electrical fault is detected, the RCD will trip and cut off the electricity supply to prevent any electric shock hazards.

RCDs in EV charger

Types of RCD

There are several types of RCDs available for use in EV chargers, including Type A, Type AC, and Type B RCDs. Type A RCDs are the most sensitive, detecting both AC and DC current, while Type AC RCDs detect only AC current.

Type B RCDs are the most advanced, detecting all types of currents, and are usually required in high-risk installations.

When selecting an RCD for an EV charger, it’s important to consider factors such as the charging rate and the location of the charger.

A qualified electrician should be consulted to ensure the correct RCD is selected and installed.

Types of RCDs


Common Issues with RCD

Here are some common issues that can occur with RCDs specifically in EV chargers:

  • Incompatibility with charging modes:

Some RCDs may not be compatible with all charging modes used in EV chargers. For example, an RCD designed for Mode 2 charging may not work correctly with a Mode 3 charging system.

  • Voltage drop:

When an RCD trips, it can cause a temporary interruption in power to the EV charger, which can result in a voltage drop. This can potentially damage the EV charger or cause charging to be slower than usual.

  • False tripping:

RCDs can sometimes trip even when there is no real fault, which can be caused by issues such as electromagnetic interference (EMI) or voltage spikes.

  • Aging:

Like any electrical component, RCDs can become less effective over time, and they need to be replaced regularly to ensure they are functioning properly.

  • Environmental factors:

RCDs used in outdoor EV chargers may be exposed to extreme temperatures or moisture, which can affect their performance and lifespan.

If you experience any issues with RCDs in your EV charger, it is important to address them promptly and seek professional assistance if necessary. Regular maintenance and testing can help to prevent issues and ensure the safe and efficient operation of your EV charger.

Installation and maintenance of RCD in EV chargers

Proper installation and maintenance of RCDs in EV chargers are critical to ensure their effectiveness. Installation shall be carried out by qualified electricians in accordance with relevant standards and regulations.

Tests and inspections should also be conducted regularly to ensure that the RCD is working properly. Issues such as nuisance tripping can arise, but these can usually be addressed by a qualified electrician.

In addition to proper installation and maintenance, there are some best practices to follow when using an EV charger with an RCD.

For example, avoid using extension cords or adapters, which can increase the risk of ground faults. Also, ensure that the charger is plugged into a properly grounded outlet.

Installation RCDs in EV chargers


In conclusion, RCDs are a critical component of safe and reliable EV charging infrastructure. They protect against ground faults, water ingress, and electrical arcing, among other risks.

There are several different types of RCDs available for use in EV chargers, and careful consideration should be given to the selection and installation of the appropriate device.

Proper maintenance and testing are also essential to ensure that RCDs continue to function effectively over time.

With the right RCDs and best practices in place, EV charging infrastructure can be both safe and reliable, helping to accelerate the transition to a cleaner, more sustainable transportation system.

Bluesky’s wall-mounted AC EV Charger with Type A RCD protection

Wenzhou Bluesky Energy Technology Co., Ltd is a professional in manufacturing EV chargers for nearly 5+ years.

We produce a variety of AC EV Chargers with Type A RCD which is the most sensitive. Our latest mini wall box AC EV Charger is equipped with Type A RCD protection.

It plays a critical role in ensuring the safe and reliable charging of EV Chargers. In the meantime, you can also use the AC EV Charger through our home APP. And we will offer one year’s after-sales service.

wallbox EV charger

For more products, please visit our official website or Alibaba store. Also, you can check out more information on Facebook or YouTube.

Further Reading

  1. Home EV Charger in Hot Sale
  2. What is EV Charging Load Balancing
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