How to use an extension lead to charge your electric car

slx outdoor extension lead for ev charging

Top rated product

SLx Outdoor Extension Lead 20m

A weatherproof 20m or 30m extension reel with a 2 way splashproof socket, thermal cut-out protection, tangle free retractable cable, and BS EN 61242 certification. Priced around £40 with a 12-month warranty.

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If your granny cable doesn’t reach the socket, you can use a heavy-duty 13A extension lead to bridge the gap. You will get around 8 miles of range per hour.

An extension lead can be used to charge an electric car as long as the socket and extension lead are safe to use. However, it should be noted that they are not designed to supply the maximum power for a prolonged period. Drawing maximum power generates heat which can become excessive.

You should not use extension leads rated lower than 13A because they are only designed to power low current appliances and gadgets. Never use a domestic multi-socket extension lead to charge an electric car.

If you only need 10m of extension cable, we recommend this:

Status cable reel extension

We recommend

STATUS 2 Cable Reel

This 10 metre cable reel from Status provides 2 sockets and thermal cut-out protection for safe power access. With BS EN 61242 certification and a 13 amp plug, it has a 5 amp/1200 watt capacity. Perfect for tidy, protected power delivery in DIY, industrial, and domestic applications.

You can also get the same design with a grab handle and 18m cable:

status 2 18m extension

We recommend

STATUS 2 Socket Cable Reel 18m

This 18m extension reel has a grab handle and a thermal cut out, rated 13A for heavy-duty applications. It only costs around £18.

The STATUS cable reel above is a fantastic product, but if you need more than 18m of cable, the STATUS 2 Socket Cable Reel 20m is perfect:

status 2 cable reel 20m

We recommend

STATUS 2 Socket Cable Reel 20m

A versatile outdoor cable reel with 20m length, weatherproof design, thermal cut-out for safety, overload protection, and a 5-way binding post for wide compatibility.

Not a fan of the green? Check out this orange extension reel from Masterplug:

masterplug extension reel

We recommend

Masterplug HLP2013/2IP 

A 20m extension reel with a thermal cut-out to prevent risk of fire caused by power overload. Has an IP54 dust and moisture proof rating, making it ideal for outdoor use.

If you need 40m of cable, this one fits the bill:

slx 40m extension reel

We recommend

SLx Outdoor Extension Lead, 40m

This robust 4-socket extension reel has a metal frame and a wide base so it stands up on its own. The plug is BSI approved with a 13A fused mains and it has a thermal cut out for safety. It’s priced at around £45 with a 12-month warranty.

Prefer your extension reels attached securely to a wall? We recommend this extension reel from SuperHandy:

superhandy extension reel wall mounted

We recommend

SuperHandy Cord Reel Retractable

Featuring a commercial grade cord, triple tap connector and IP64 weather rating, this 15A wall-mounted extension reel delivers reliable power with a 15m cable – ideal for charging your EV at home. It’s priced around £110.

Another good idea is to place an outdoor socket closer to your electric car, such as on an external wall. Something like this will do nicely:

weatherproof outdoor socket

We recommend

RICOKEY Weatherproof Outdoor Socket

Fully waterproof outdoor socket with neon indicators, heavy-duty cable, clear locking cover, and 2 year guarantee – perfect for charging your electric vehicle with complete weather protection.

This weatherproof outdoor socket provides the perfect 3-pin hook up point for your extension cable, and you can lock it when not in use.

3 pin extension cable for EV charging

Some EV charging cables have a 3 pin plug to connect the cable to a wall outlet. EV owners may find the cable that came with their car or charging station is not long enough to conveniently reach their parking spot. This is where a 3 pin extension cable can help. A high quality 3 pin extension cord allows you to safely extend the reach of your existing EV charging cable.

When selecting the best EV charging cables for your lifestyle, be sure to match the amperage rating to your EV charging equipment – often 16A or 32A. The pins and sockets should be sturdy and weatherproof.

For outdoor use, choose an extension cable specifically designed for outdoor use with UV and water resistance. Look for versions with a cable management system to neatly coil any excess cable. With the right 3 pin extension cord, you can conveniently charge your EV even when parked far from the power source.

Safety and fire hazards with extension cables for EV charging

Extension leads are considered a fire hazard by some manufacturers. The risk comes from overheating because most extension cords are not designed to be used for the duration it takes to charge an EV.

Additionally, only use 3-pin plugs to charge your electric car you have confidence in. 3-pin sockets are not designed to deliver maximum current for hours at a time.

Most EV manufacturers don’t recommend extension cords because they have no control over the quality of third-party products. If in doubt, ask the manufacturer of the product for advice before using it.

Heavy duty extension lead for charging electric car

Charging an electric car often requires a heavy duty extension lead to bridge the gap between the charging point and where you’ve parked. A standard lead may not be up to the demands of EV charging. Look for an extension lead specifically designed for EV charging, rated for at least 13A to 15A depending on your charging equipment.

Something like the GONEO EV charging cable (affiliate link to Amazon) might also work well – this has a 5m cable length for Type 2 to Type 2.

Choose a heavy duty cable with multiple stranded pure copper cores to efficiently handle the sustained high loads. The plugs and connectors should be sturdy and weatherproof – heat and moisture resistance are must-haves for outdoor use.

For maximum safety, opt for an extension lead with built-in circuit protection. Choose the shortest lead that will reach your parking spot to minimise voltage drop. A cable management system helps control cables. Investing in a good quality heavy duty extension lead makes home EV charging easy and convenient, even when parked far from the power source.

Can I use an extension lead to charge my electric car?

Yes, you can charge your electric car with an extension lead, but we only recommend extension cords rated 13A or over for continuous power (sold as heavy-duty).

The extension lead needs to be waterproof and rated for outdoor use if it will be exposed outdoors.

The reason we recommend a 13A heavy-duty extension lead is that anything lower can overheat charging an electric car.

However, bear in mind that most extension leads are not designed to remain in use for the time it takes to charge an electric car. You should ask the extension lead manufacturer if you have any doubts about safety.

Plugging into a 2.3kW 3-pin socket will give you around 8 miles of range in 60 minutes, which might be enough to limp you to a public charger. It isn’t powerful enough to replenish an electric car battery overnight, unless you start at 90%.

How to using an extension lead to charge an electric car safely

Using an extension cord to charge your electric vehicle can be safe and convenient if done properly. However, incorrect use of extension cords can potentially cause fires, electrocution hazards, and damage to your EV charging equipment. Follow these important guidelines when using an extension cord for EV charging:

First, never use a basic multi-outlet power strip or household extension cord. These are only rated for low-power devices like lamps and phone chargers, not the high power draw of an EV charger. You must use a heavy-duty 13 amp extension cord specifically rated for high-wattage appliances. Also inspect the extension cord thoroughly before each use to ensure there are no frays, cracks, or exposed wires.

If the extension cord will be used outdoors, be sure to only use cords rated for outdoor use that are waterproof. Exposure to moisture significantly increases electrocution and fire risks. Fully unravel any extension cord on a reel rather than leaving it coiled up, as this allows heat to dissipate properly during charging.

Check that the wall outlet you’re plugging into is grounded and in good condition without cracks or burn marks. Loose, damaged, or ungrounded outlets present serious hazards. Keep an eye on the temperature of the wall outlet, extension cord, and EV charger during charging. If any of these feel too hot to comfortably touch, discontinue charging immediately.

By following these safety tips, keeping cords in good repair, and monitoring charging conditions, using an extension cord for EV charging can be safe and convenient. But never overload an undersized cord or use damaged, fraying, or inadequate cords. Invest in a heavy-duty extension cord designed for EV charging to protect your safety.

What does your EV manufacturer say?

Check with your manufacturer and follow their advice first and foremost.

Some EV manufacturers, such as BMW, recommend that you don’t use an extension cord to charge your electric car. They cite fire hazards as the reason. Other manufacturers sell adapters.

Never daisy chain extension leads

Daisy-chaining extension leads is extremely dangerous because it increases heat and risks spikes in the power supply. You risk overloading the cable which will trip the circuit breaker and could cause a fire.

The bottom line is if you need emergency power and have access to a 13A extension lead, using it for an hour or so should be fine – but keep an eye on it for heat. Avoid extension cords you are unsure about for safety reasons.

Can I charge overnight with an extension cord?

Yes, you can charge overnight but use a 13A extension lead, fully uncoiled. You will add around 60-miles of range from 8-hours of charging.

For faster-charging speeds, get an electrician to install a Commando socket or a smart charger. 16A Commando sockets charge at speeds of 3.6kW (15 miles of range per hour) while 32A chargers go up to 7.4kW (30 miles of range per hour.

Best smart chargers to consider

3-pin sockets and Commando sockets get the job done, but smart chargers are better because they let you schedule charge times and integrate your EV tariff for kWh price caps.

Check out our EV charger reviews for ideas, or start with these:

  • Hypervolt Home 3 Pro: A stylish, well-made smart charger with a decent app and solar integration, so you can charge with solar panels.
  • Easee One: The Easee One is an excellent charger (read our full Easee One review). It offers 7.4kW charge speeds, RFID, cable locking (to turn the untethered charger into a tethered charger) and a good app with smart scheduling.
  • Wallbox Pulsar Plus: Another solid choice is the Wallbox Pulsar Plus (read our full Wallbox Pulsar Plus review). It’s the smallest smart charger we’ve tested and a great option if you want something inconspicuous.
  • Ohme ePod: An excellent untethered charger with one of the best apps in the business, letting you integrate your dynamic pricing tariff and set kWh price caps.

Overall

Charging an electric car with an extension lead is perfectly safe so long as you use the right extension lead. You can use a granny charger extension lead designed for the job, or a 13A heavy-duty extension lead rated for outdoor use.

Never use a domestic multi-socket extension lead, and if you have any doubts about the safety of an extension lead or socket, don’t use them.

Alfred drives a Tesla Model 3 Standard Range Plus but has his eye on a fully-electric pick-up truck. He'd love an electric Ford Ranger, which should be a real thing in a few years!