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How to buy an EV charger extension cable

Read our tips on buying an extension cable for your electric car!
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Summary
  • You can use an EV extension cable to charge your electric car.
  • However, car extension leads aren’t the safest or most efficient way to charge your vehicle, so they should only be used as a last resort.
  • Only waterproof, heavy duty 13-amp EV charger extension cables are suitable for charging an electric vehicle — never use a standard home extension lead.
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The EV charging infrastructure is getting better all the time. But there’s still room for improvement. Many EV drivers — especially those who don’t have dedicated home charging points, or live far from free public charging stations — use an EV charging cable extension to charge their electric car.

Using a car extension lead can help if you haven’t committed to installing a home charging point yet. Many people who get an electric car on subscription want to trial the technology before making a larger commitment, so they use car charger extension cables instead.

But there are safety and efficiency concerns around using certain extension cables to charge your car. In this article, you’ll learn:

  • If it’s safe to use an EV charger extension cable
  • How an extension cable affects car charging times
  • How to choose an EV extension cable for your vehicle.

Can I use an extension lead to charge my car?

Yes, but you should only use a heavy duty extension lead for charging an electric car. Most extension cords aren’t designed to deliver maximum charge for several hours at a time. This increases the risk of overheating and other safety issues.

Car extension leads must be at least 13-amp and rated for outdoor use. They must be waterproof (not just weatherproof) and free from defects. Standard home extension leads aren’t suitable for charging your electric car.

Do you need an EV extension cable?

Using an EV extension cable to charge your car should be a last resort. Many EV manufacturers discourage drivers from using extension cables to charge their car.

That said, EV extension cables can be a useful stopgap solution if:

  • You’re waiting for a home charge point to be installed.
  • You’re trialling an electric car and don’t want to commit to charge point installation just yet.
  • You need to extend the reach of your granny charger.
  • You need a small amount to charge to get your car to a public charging station.

It’s also a good idea to make sure you have a good EV tariff if you’re planning to charge at home frequently.

Home extension leads vs car extension leads

Standard domestic extension leads aren’t safe or suitable for charging a car. They’re not always waterproof, and rarely have the required power for effective charging.

Here are the key differences between a home extension lead and a heavy-duty car charger extension cable:

  Home extension lead EV extension lead
Power/current Typically 10-13 amps Must be minimum 13 amps
Weatherproofing Typically IP54 (protected against some dust and low pressure water splashes) Must be IP66 or higher (total protection against dust and high pressure water jets)
Sockets Multi-socket Single-socket only
Cable diameter 1-1.25mm² 1.5mm²+
Temperature exposure Not suitable for use below 5°C Suitable for use between -25°C and 55°C

Tips for using an extension lead to charge an EV

  • Only use EV extension cables that meet all the criteria above — don’t be tempted to use a standard domestic extension lead.
  • Never plug multiple extension leads into each other to increase length (also known as daisy-chaining).
  • Unravel the cable fully before use to minimise the risk of overheating.
  • Check the cable and plug for defects (such as exposed wires or broken plastic) before you plug the extension lead in. Never use a broken or defective extension lead.
  • Use an EV pavement cable protector to prevent damage to the lead when in use.

Can I use an EV extension cable to charge my car overnight?

Yes, but take extra safety precautions to reduce fire hazards. Carry out all the above checks before plugging in your car.

Also, consider other security issues. Don’t leave windows open overnight to charge your car. Plug your extension lead into an external socket only. If possible, use a lockable socket so the extension lead can’t be removed.

Does an extension cord affect fast charging?

Yes. Relying on a 3-point plug is slower than charging with a purpose-built EV charger anyway. But adding an extension lead can reduce charging speed even further.

Charging speed depends on the power of your EV charging cable and your extension lead. If your extension lead has a lower power output than your charging cable, it will limit the charging speed.

Here are some examples based on a 230V voltage (standard for a UK plug socket):

EV charger current Extension lead current Charge speed*
16 amp (3.6kw) 10 amp (2.3kw) 10 amp (22 hours)
16 amp (3.6kw) 13 amp (2.99kw) 13 amp (17 hours)
16 amp (3.6kw) 16 amp (3.6kw) 16 amp (14.5 hours)
13 amp (2.99kw) 16 amp (3.6kw) 13 amp (17 hours)

*Approximate times based on charging a Renault Zoe with a 52kWh battery.

By comparison, a rapid, non-extended charger has a power output of up to 50kw. So it could charge the same car to full capacity in just over an hour. Learn more about EV charging times.

How to choose the best EV extension cable

Here’s what to look for in the best car charger extension leads. The best EV extension cables must be:

  • Waterproof — with an IP rating of IP66 or higher (ideally IP67).
  • Heavy duty — power output should be no less than 13A, and cable thickness must be no less than 1.5mm².
  • Free from defects — all wires should be fully concealed and plugs should have no broken sections.

Your EV extension cable should also have an RCD (residual current device) included. This can prevent potentially fatal electric shocks. We could find leads starting from about £69 (budget option so read reviews first), all the way up to £220 (high-end brand). In our research we found this one provided a good balance between cost and positive reviews.

Finding a public charge point in the UK

There are more than 37,000 public charging points in the UK — and more are being added to the network all the time. Public charging points are much safer and faster than using an extension lead at home. Some even offer free charging. So if you don’t have a home charge point, it may be better to rely on public charging stations where you can.

Use our electric car charging points map to find local charging stations where you can top up your EV safely and efficiently. There are also charging apps for electric car owners to help you find a charging station when you’re on the road.

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