You hardly see them once the work is finished, but electrical boxes are essential for a safe installation: they protect the connections, prevent short circuits and make future work easier. Here is how to choose the right box for each use on your project.
Contents
Types of electrical boxes at a glance
| Box | Role | Where? |
|---|---|---|
| Flush-mounted | Holds a socket or a switch | In the wall, behind each wiring device |
| Junction | Connects and distributes the wires | In the wall or ceiling, accessible |
| Waterproof | Protects connections from water and dust | Outdoors, garage, garden, damp rooms |
| AC pre-installation | Prepares the air conditioner connections | Behind the indoor unit |
The flush-mounted box
It is set into the wall and holds the mechanism of the socket or switch. Choose a box deep enough if you plan to add a smart home module behind the switch. Example: LAP maxi 50 mm square flush-mounted box.
The junction box
This is where wires are connected together to supply several points (lights, sockets). All connections must be made inside a box, never directly in the conduit or in the wall, and the box must remain accessible. Choose the size according to the number of cables:
- Round junction box: small connections.
- Flush-mounted 10 × 10 cm and 13 × 13 cm (LAP): everyday use.
- Flush-mounted 15 × 15 cm Solera: many cables, main circuits.
Brico MIM tip: always choose a box slightly larger than you need. Wires packed too tightly heat up and make future work difficult.
The waterproof box: for outdoors and damp rooms
Garden, façade, garage, laundry room, pump or pool room: connections there must be protected from water and dust. Examples: 8 × 8 cm waterproof box, 100 × 100 mm, 180 × 140 mm and 24 × 18 cm. Essential for connecting your garden lighting.
The air conditioner pre-installation box
Flush-mounted in the wall where the indoor unit will go, it neatly groups the refrigerant lines, the condensate drain and the power supply. The result: no unsightly trunking, and an easier air conditioner installation, even years after construction. Examples: Solera pre-installation box ref. 178 and Solera flush-mounted pre-installation box. See also our article on air conditioner maintenance and installation.
Frequently asked questions
Can you make a connection without a junction box?
No. Every connection must be placed in a closed, accessible box, for safety and so that you can work on it later.
Is a waterproof box mandatory outdoors?
Yes. Outdoors and in damp rooms, use suitable waterproof boxes.
What about the electrical panel?
Read our guide to choosing your electrical panel.
Equip your electrical project
LAP and Solera boxes, Hager, Ingelec and OGE panels.
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