There is a small box on the wall of the bathroom to protect against leakage, what is it called

It is called equipotential coupling terminal box, and its function is mainly to prevent electric shock. When people take a bath, there is water vapor on the wall and on the ground, and once electricity leaks from a certain location, the current will be conducted in the path formed by water vapor, causing people to be electrocuted. The equipotential junction box will form a path with water vapor, and when leakage occurs, the current will be conducted along this path to the ground to prevent people from being electrocuted.

It is called equipotential coupling terminal box, and its function is mainly to prevent electric shock. When people take a bath, there is water vapor on the wall and on the ground, and once electricity leaks from a certain location, the current will be conducted in the path formed by water vapor, causing people to be electrocuted. The equipotential bonding terminal box will form a path with water vapor, and in the event of leakage, the current will be conducted along this path to the ground to prevent personnel from being electrocuted.

The installation of switches and sockets is called a splash-proof box.

In a relatively large location, about 30cm from the ground is called an equipotential connection box.

"Equipotential Bonded Terminal Box".