Is it safe to charge an electric car overnight with a 3-pin plug?

is charging an electric car with a 3-pin plug overnight safe

A 3-pin plug is the entry point to charging at home for many EV owners. Whether it’s the only option due to problems getting a Type 2 wall socket installed, or a convenient way to top up 40 miles of range overnight, 3-pin sockets do an admirable job.

In our experience, charging an electric car with a 3-pin plug is perfectly safe overnight if done correctly. That is, you need to step down the load rating to 6A to reduce heat build-up. Here’s what you need to know.

Overnight 3-pin electric car charging – how to assure the safety of the cable and socket

There are two factors at play regarding safety when charging an electric car overnight with a 3-pin plug – the charging cable, and the socket.

The socket

To avoid overheating hazards, carefully match your EV charging equipment to the proper wall socket. Most household sockets have a 13A load rating but some only have a 10A rating. While adequate for lower overnight charging loads, a 10A socket leaves little headroom for faster daytime charging.

When using a 3-pin socket to charge an electric car overnight, confirm it is in good condition with no signs of defects or deterioration – cracked casing, overheating damage, misaligned pin connectors, dodgy switches. These indicate it cannot safely sustain EV loads or anything else for that matter.

Use only sturdy, dedicated extension cords rated for at least 13A loads, and never link multiple extension cords. Instead, employ a fused multi-way bar for additional capacity. Avoid cheap non-fused sockets without overload protection.

Pay close attention to your electrical system for any smell of burning plastic, scorched outlets, frequently tripped breakers, or blinking lights indicating strain on the circuits. These may be signs of unsafe overloading. If detected, stop charging immediately and contact an electrician to inspect for damage or inadequate capacity.

The charging cable

When selecting the best EV charging cables for overnight charging, the key is identifying well-made cables certified to handle high loads. Start by looking for an established manufacturer’s logo and verifiable model details like a batch number. Quality cables meet IEC safety standards IEC 61851, IEC 61557, and IEC 62196 for EV conductive charging systems.

Check that the cable bears a CE conformity marking. This declares the manufacturer attests the product meets European safety law – but beware, counterfeit CE marks are common. So while a authentic CE label is reassuring, it does not guarantee safety on its own.

Carefully match the cable’s voltage and amperage ratings to your electric car’s charging capacity and your electrical socket’s load rating. Do not exceed these, especially for extended overnight charging sessions.

Also inspect the plug and cable insulation for defects before each use. Even quality cables can deteriorate over time under intense EV charging loads.

Basically, ensure the 3-pin charging cable meets all UK safety certifications by only buying from reputable retailers or directly from manufacturers who rigorously test their products.

3-Pin Socket Load Ratings

The key specification to understand is that 3-pin sockets and the wiring behind them have a maximum load rating of 13 amps (13A). This is enough to replenish around 8 miles of electric car range per hour in optimal charging conditions.

While 13 amps is a safe load level for a 3-pin socket, there is a heat build-up factor to consider – 3-pin sockets and plugs are not designed for high loads over extended periods of time such as charging an electric car overnight.

Compare this to 240v, 32Amp connections to the building consumer unit for Type 2 EV chargers like the Pod Point Solo 3 – 3-pin chargers are simply rated for much less load.

Pulling 13A continuously for 8+ hours generates significant heat which can damage the cable, plug, and socket. To put this into context, irons and tumble dryers draw close to 13A, but this is only for short bursts, not for hours at a time.

For this reason, we do not recommend charging an electric car overnight at the full 13A rate that 3-pin sockets are rated for. Instead, step the load down.

Stepping Down the Charging Load

The good news is that most portable 3-pin EV chargers allow you to step down the amperage load to reduce heat build-up. For example, the VORSPRUNG® Portable EV Charger Type 2 cable with adjustable load levels lets you dial it down to as low as 6A.

When charging an electric car overnight, we recommend keeping the load at 6A maximum, which will provide around 4 miles of range per hour, or up to 32 miles after an eight hour charge. This balances range replenishment with safety.

Why Some Claim 3-Pin Charging Is Unsafe

There is a risk of overheating and damage if a 3-pin socket, cable, and plug are left pulling high loads for extended periods.

This is especially true if older parts rated for lower loads are used. The risk is not to the vehicle being charged, but to the charging equipment itself.

To ensure safe overnight charging, we recommend installing a brand new, dedicated 3-pin socket rated and wired for 13A loads, even if you plan to use lower 8A or 6A settings. Do not use an existing random indoor or outdoor socket without inspection, as its condition and wiring is likely inadequate for high load EV charging.

You should also buy the best EV charging cable you can afford – 3-pin EV chargers cost from £120 to £200 on average with an 8m cable.

Adjustable chargers allow you to mitigate most risks, but vigilance is still required to ensure you select a lower amperage. You should also inspect sockets and cables periodically for heat damage and replace deteriorated parts immediately.

Summing Up

Charging an electric car overnight with a standard household 3-pin plug is safe when done properly. Use a dedicated 16A-rated socket, quality EV charging cable with adjustable loads, and do not exceed 8A during overnight charging sessions.

Limiting the amperage avoids potential overheating while still providing meaningful range replenishment. Be diligent about equipment inspections and you can enjoy the convenience of low-cost home charging. Just remember – while 3-pin charging unlocks flexibility, exercise caution and never push the limits of your electrical system.

Jakk is the founder and chief editor of Top Charger. He drives a Volkswagen ID.3 Family Pro Performance, and despite having a lead right foot, he consistently gets over 200-miles of range.