You do not strictly need a dedicated home charger to run an electric car. Every car comes able to charge from an ordinary three-pin socket, and for some drivers that is genuinely enough. But a proper 7kW wallbox charges roughly three times faster, is built for the sustained load, and can schedule itself to run only in your cheap overnight window. This guide works out who actually needs one and who can manage without.
The short answer. A three-pin plug, the so-called granny cable, adds about 8 miles of range an hour. A 7kW home wallbox adds roughly 25 to 30. If you drive modest daily miles and park off-street overnight, a granny cable can keep up; if you cover bigger distances or want charging to happen automatically in the cheap hours, a wallbox earns its keep. Fitting one typically costs somewhere in the region of 800 to 1,200 pounds installed, and you need off-street parking to put it on.
The two ways to charge at home
Home charging comes in two forms. The first is the cable supplied with the car, which plugs into a normal three-pin domestic socket. It is often nicknamed a granny cable, and it draws a modest amount of power, limited to what a household socket can safely deliver continuously, usually around 2.3 kilowatts. The second is a dedicated wall-mounted charge point, a wallbox, wired into your home's electrical supply on its own circuit and typically rated at 7kW. That is roughly three times the power, and the difference shows up entirely in how fast the car fills.
| Charging method | Power | Range added per hour | Empty to full, 60 kWh |
|---|---|---|---|
| Three-pin plug (granny cable) | ~2.3 kW | ~8 miles | ~24 to 26 hours |
| 7kW home wallbox | 7 kW | ~25 to 30 miles | ~8 to 9 hours |
Range added per hour assumes about 3.5 miles per kWh; see the miles per kWh guide. Charging from completely empty to completely full is rare in practice; most home charging is an overnight top-up of whatever you used that day.
Why the granny cable can be enough
The slow figure looks alarming until you do the arithmetic on real driving. The average car covers well under 30 miles a day, and at 8 miles of range an hour a three-pin plug replaces that in around four hours, comfortably inside an overnight charge. If you park off-street, plug in every evening, and drive ordinary daily distances, the granny cable quietly keeps the battery topped up while you sleep, and you may never need anything faster. It is the long charge from near-empty, or the day you come home late and need a big top-up before an early start, that exposes its limits. As an everyday trickle for a modest commute, though, it genuinely works, and starting with it costs nothing extra.
Where the granny cable falls short
Two things count against relying on a three-pin plug. The first is simply speed: if you drive bigger daily miles, or need to recover a lot of range overnight, 8 miles an hour cannot always keep up, and you can wake to a car that is not charged enough for the day. The second is the load. A domestic socket and its wiring are not designed for many hours of heavy continuous draw night after night, and an old or worn socket can run warm under that duty. A granny cable should be plugged straight into a known-good wall socket, never through an extension lead or a multi-way adaptor, and it is worth having the socket and circuit checked if you intend to lean on it regularly. A wallbox sidesteps the problem entirely, because it is purpose-built for exactly this job.
The case for a 7kW wallbox
A dedicated wallbox buys three things. The obvious one is speed, refilling the car in a single overnight window even from a low state of charge, so charging never becomes the thing you have to plan around. The second is that it is designed for sustained charging on its own protected circuit, which is safer and steadier than asking a household socket to do the work for hours on end. The third, and quietly the most valuable, is control. A wallbox can be set to charge only during your cheap off-peak hours, switching on and off by itself, so plugging in when you get home becomes a charge that happens automatically at the lowest rate while you sleep. That automatic off-peak scheduling, covered in the best time to charge guide, is what turns the theoretical 2p-a-mile cost from the home charging cost guide into what you actually pay, without you having to babysit a plug at midnight.
What a wallbox costs and what you need
Fitting a 7kW home charger typically runs somewhere in the region of 800 to 1,200 pounds including installation, depending on the unit you choose and how far it sits from your fuse board, with a long or awkward cable run adding to the labour. The practical requirement is off-street parking, a driveway or garage where the car sits next to the wall the box mounts on, since you cannot trail a cable across a public pavement. The installer will check your home's electrical supply and consumer unit can take the extra circuit, which most modern installations can. Support schemes exist in some cases, for instance for people in rented homes or flats without their own driveway, but the details and eligibility change, so check the current position rather than assuming a grant applies. Set against years of cheap, effortless overnight charging, the one-off cost is usually money well spent for anyone charging at home regularly.
Which one suits you
The honest dividing line is your mileage and your parking. If you have off-street parking, drive modest daily distances, and are happy to plug in every night, start with the granny cable that came with the car and see whether it keeps up, because it may well do and it costs nothing to try. If you cover bigger miles, sometimes need a large overnight top-up, or simply want charging to handle itself in the cheap hours without thought, a 7kW wallbox is worth fitting and quickly becomes invisible in the good way. What matters far more than which one you use is that you are charging at home at all, on the right tariff, in the off-peak window. Get that right and either method delivers the running-cost advantage that makes an electric car so cheap to fuel.
The bottom line
A three-pin granny cable adds about 8 miles of range an hour, which is enough for modest daily driving with off-street parking, but it is slow, leans hard on a domestic socket, and means manual timing. A 7kW wallbox adds three times the range an hour, is built for the load, and crucially schedules itself into your cheap overnight window. For light users the cable is a fine free start; for everyone charging regularly at home, the wallbox pays its way in speed, safety and effortless off-peak charging.