What is a Junction Box?
A junction box protects electrical connections that you need to make when creating a bypass, bridge, or electrical connection. Installing a junction box provides physical protection that adapts to the environment and location where it's installed.
Junction Box: How to Choose Based on Your Needs
Indoor Installation, Without Flush Mounting
If you need a box for an indoor branch line and cannot flush mount it, you should choose a surface-mounted junction box.
Damp or Dusty Environment
If the room where you're installing your junction box is exposed to humidity or dust, and the installation is surface-mounted, you'll need a watertight junction box.
Box for Centralized Junctions
You'll also find "octopus" boxes on the market that allow you to centralize all branches of your installation at a single central point. These boxes can be either flush-mounted or surface-mounted.
The Surface-Mounted Junction Box
Surface-Mounted Junction Box - Standard Use
In this case, you won't have specific environmental constraints (no humidity, no dust), but you'll need to install it on the surface since conventional surface-mounted junction boxes cannot be recessed.
Surface-Mounted Junction Box - Damp or Dusty Environment
Cables can be passed through watertight junction boxes in different ways, depending on the model:
- Junction boxes with spigots allow cables to be inserted directly through an opening that ensures watertightness. Some models come equipped with terminal blocks, eliminating the need for additional components.
- Smooth junction boxes don't have prefabricated inlets, offering greater flexibility for cable type and quantity. However, they must always be supplemented with cable glands. Smooth junction boxes come in various sizes and materials, including polyester, metal, or plastic.
Note: A watertight junction box is designed to resist moisture or dust. Don't confuse it with an airtight box, which serves different technical requirements.
The Flush-Mount Junction Box
Junction Box for Flush Mounting in Lightweight Partitions
If you need to flush-mount a junction box, you have two options:
- For lightweight partitions (like plasterboard or drywall), use a box specifically adapted to this type of material. Some models can be airtight, helping to meet energy performance requirements.You will also find drywall junction boxes that are airtight.
Junction Box for Other Materials
- For embedding in different materials (such as concrete, brick, or any other solid support), choose a junction box designed for embedding. This type of box is engineered to withstand solid embedding. By comparison, a box designed for lightweight partitions wouldn't be strong enough for this application.
There are also multi-material junction boxes available that adapt to different types of walls, whether solid or hollow.
Junction Box for Outdoor Ground Installation
To install a junction box in outdoor ground, you'll need a buried junction box, also known as a resin or gel junction box. This type of installation is necessary when extending a buried cable.
The underground junction box is specially designed for this purpose, consisting of a base box and a liquid (gel) or solid (resin) sealing component. This system makes the connection completely watertight.
