What is a wallbox? Types and what power to choose

If you're thinking about switching to an electric car, sooner or later the word wallbox comes up. It sounds like a specific product, but it's really the name that has become popular for the home charging point: a box fixed to the wall (or a post) that manages your car's charging.

In this guide we explain what it is, what types exist and, above all, how to decide on the power without overpaying or falling short.

What a wallbox is and how it differs from a socket #

A household socket can charge an electric car, but it isn't designed to do so for many hours in a row. A wallbox is:

• Installed on a dedicated circuit, with its own protective devices.
• Communicates with the car (known as mode 3) to adjust the current and cut off charging if something fails.
• Uses a type 2 connector, the European standard for AC charging.
• Lets you schedule charging times and, on many models, measure consumption.

A domestic socket charges slowly and requires an installation that isn't always designed for that kind of sustained use. A wallbox is built precisely for that.

Many models also include residual DC current detection, a protection required by the installation standard for charging points (ITC-BT-52).

Types of wallbox #

Single-phase and three-phase #

This is the most important difference, because it sets the maximum power:

• Single-phase: up to around 7.4 kW. The most common choice for homes.
• Three-phase: up to 11 kW or 22 kW, as long as your supply is three-phase and your car supports it.

With or without load management #

• Without management: charges at the fixed power you've set.
• With dynamic load management: adjusts the power based on the rest of the home's (or garage's) consumption, so it doesn't trip the main breaker when you turn on the oven or the air conditioning. Especially useful in community garages, where several neighbours may share infrastructure.

With or without connectivity #

Some models connect via wifi or Bluetooth and can be controlled from your phone. Others include OCPP, a standard protocol that lets the charger be managed from an external platform. This matters little in a house and a lot in a community or a business that wants to charge for the electricity used.

Fixed cable or socket #

Some wallboxes come with a built-in cable; others have a type 2 socket and you use your car's own cable. A fixed cable is more convenient; a socket gives you flexibility if you change vehicles.

What power to choose #

Wallbox power is measured in kilowatts (kW). More kW means faster charging, but only if your car can make use of it.

To give you an idea, this table shows how long it would take to charge 48 kWh (from 20% to 100% on a 60 kWh battery), not counting losses:

Calculation: energy to charge ÷ power. This is a theoretical estimate: the real time depends on the car, the temperature and the battery itself.

First filter: what your car can accept #

Every car has a built-in charger (onboard charger) that limits the AC charging power. If yours accepts 7.4 kW, installing an 11 kW wallbox won't make it charge any faster. Check the manual or the technical specs before deciding.

Second filter: your contracted power #

This is where many people get it wrong. If you have, say, 4.6 or 5.75 kW contracted, a 7.4 kW charger running at full power would leave no margin for the rest of the house. The solutions are:

1. Limit the wallbox's power so it fits your contract.
2. Install a model with dynamic load management.
3. Increase your contracted power (with the fixed cost that adds to your bill).

Third filter: how many hours it stays plugged in #

If the car spends the whole night at home, you don't need maximum power: 8 or 10 hours with a 3.7 or 7.4 kW charger is usually enough for normal daily use. Higher power pays off if you drive a lot of kilometres a day or share the charger between several cars.

What to check before buying a wallbox #

Before settling on a model, check this list:

• Compatibility with your car (type 2 connector and supported power).
• Adjustable power, so you can match it to your contract.
• Dynamic load management, if you live in a block of flats or have low contracted power.
• Built-in protections and CE marking.
• Scheduled charging, so you can charge during the cheapest hours.
• Connectivity and OCPP, only if you'll actually use them.
• Warranty and after-sales support in your area.

And a practical warning: the equipment is only part of the cost. The installation (wiring, protections, distance to the fuse box) often weighs as much, or more, than the wallbox itself. You can see indicative ranges in our guide on how much it costs to install a charger in Granada.

Installation and certification #

A wallbox is not a "plug it in and you're done" product. It must be installed by an authorised electrical installer, who will take care of:

1. Sizing the circuit and the protective devices.
2. Complying with ITC-BT-52 of the Low Voltage Electrotechnical Regulation.
3. Giving you the installation documentation (certificate, depending on the case).

If you live in a building, you'll also need to notify your homeowners' association. We cover that in our community garage guide. And if you want to know what it'll cost you to charge each month, you'll find the calculation in how much it costs to charge an electric car at home.

If you're after the full installation service, see our home EV charger installation page.