Is it Safe to Charge an EV Using a UK Socket?

Is it Safe to Charge an EV Using a UK Socket?

There is growing concern about the safety of charging an electric vehicle (EV) using the British standard Type G BS 1363 socket, commonly referred to as a UK socket. While there is some truth to these concerns, the real answer is more nuanced and requires an understanding of the BS 1363 standard and its history.

A Brief History of BS 1363

The BS 1363 standard was introduced in 1947 to standardize domestic plugs and sockets in the UK. It is nominally rated for 13A, with testing designed to reflect typical household loads. Electric vehicles have only become mainstream in the past 15 years, prompting updates to the standard. In 2016, the BS 1363-2 standard was revised to address the increasing demand for EV charging and reflect the new use cases for domestic sockets.

Key Updates in the 2016 Revision

Introduction of Cyclic Load Testing for EV Charging

The 2016 revision of BS 1363-2 incorporated provisions for socket-outlets intended for EV charging. These changes introduced a cyclic loading test, simulating the repeated and prolonged use typical of EV charging. The test subjects the socket and switch contacts to inductive loads, replicating real-world conditions.

Marking and Identification

Socket-outlets compliant with these enhanced requirements are marked with 'EV' on the rear of the socket. This marking signifies that the socket has undergone additional cyclic load testing and is suitable for EV charging.

Is It Safe to Use a Portable Charger Rated at 13A?

The answer is both yes and no. A BS 1363-2 socket marked with 'EV' on the backplate is rated to safely charge an EV at the full 13A. However, users must assess the suitability of the socket before use, as portable chargers cannot determine the type of socket they are plugged into.

A key concern is whether the portable charger has supply plug over-temperature protection. Even EV-rated sockets can suffer damage or cause thermal runaway. As a precaution, many portable chargers are derated to 10A when used with sockets not specifically designed for EV charging. This lower current limit reduces the risk of overheating in most cases.

IET Code of Practice for EV Charging Using BS 1363 Sockets

The IET Code of Practice for Electric Vehicle Charging Equipment Installation provides detailed guidelines for the use of BS 1363 sockets for EV charging. While technically permissible in certain circumstances, these sockets are not the preferred solution. Key recommendations include:

1. Dedicated Circuit

The BS 1363 socket should be connected to a dedicated circuit, serving no other appliances to reduce the risk of overloading.

The circuit should be rated appropriately for continuous load, typically 13A.

2. Residual Current Device (RCD)

The circuit must include an RCD for protection against electric shock. A Type B RCD is recommended as it detects residual DC currents that can arise during EV charging.

3. PEN Loss Detection

The circuit should include a means of detecting and disconnecting when an open-circuit fault of the neutral (PEN conductor) occurs in a PME system.

4. Thermal Monitoring

Portable chargers should ideally include thermal monitoring to shut down or alert users if overheating occurs, which is a risk during prolonged EV charging.

5. Inspection and Maintenance

The socket must be in good condition, free from signs of wear, discoloration, or damage.

Regular inspection is recommended to ensure safety and functionality, especially for sockets frequently used for EV charging.

6. Cyclic Load Testing Compliance

Ensure the socket complies with BS 1363-2 requirements for cyclic load testing to handle the repetitive high-current loads typical of EV charging.

7. Charging Power Limit

BS 1363 sockets typically support a maximum charging power of 3 kW (13A). This rate is slower compared to dedicated EV chargers.

Conclusion

While BS 1363 sockets can be used for EV charging under specific conditions, they are not ideal. To ensure safety, prioritize using EV-rated sockets, adhere to IET Code of Practice guidelines, and consider dedicated EV chargers for regular charging. Always inspect and maintain charging equipment to mitigate risks.

 

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Written by: James Louw, BTech, MIET