Why You Should Never Charge an EV with an Extension Cord (and What to Use Instead)

A kettle draws a lot of power for two minutes. An electric car draws a similar or higher current continuously for eight to twelve hours. Household sockets, extension leads and old wiring were never designed for that kind of sustained load, and that is where the danger lies: gradual heating of a connection, a socket or a lead until insulation melts and a fire starts, often behind a wall or under a rug where nobody notices.

The specific hazards

• Domestic extension leads — thin conductors and cheap plugs overheat under a continuous 10–13 A load; a coiled lead overheats even faster because it cannot shed heat.
• Multi-way adaptors and power strips — never rated for a car's load and a notorious fire cause.
• Old or loose sockets — a worn socket makes a poor contact that heats up over hours.
• Long runs of cable — voltage drop and extra heat.
• Cables run through windows, doors or across paths — pinched, damaged or a trip hazard.

The safe options

If you must use a socket occasionally

1. Use the manufacturer's portable charging cable, plugged directly into the socket — no lead, no adaptor.
2. Choose a modern socket on a lightly loaded circuit and have an electrician check it is sound.
3. Set the cable or car to its lowest current setting (many portable chargers allow this).
4. Feel the plug and socket after an hour; if either is more than warm, stop.
5. Treat it as a stopgap, not a routine.

If the only way to reach your parking space is a long lead, the safe answer is a properly installed weatherproof outdoor socket or wallbox at the parking space — not a longer extension.