Understanding the composition of an electrical panel

An electrical panel is the central element of the electrical installation of your home. Indeed, it includes all electrical circuits and their protection systems. To understand how it works, I suggest that you take an interest in its key elements.

The differential header switch

Each row of the electrical panel must include a differential switch in the header. You also have the option of installing earth leakage switches. If you would like to know the difference between these two protective devices, I invite you to read the article on this subject.

A differential header switch is connected to all the circuit-breakers in the row. Together, they can detect current leaks caused by insulation defects. The differential switch also prevents the risk of electric shock by immediately switching off the entire row concerned. It is therefore the element of the electrical panel that protects you from the risks associated with various electrical problems.

The standard that regulates French domestic electrical installations, NF C 15-100, refers to DDR: residual current differential devices. It specifies that each electrical circuit in the housing must be protected by a 30mA differential.

The modular circuit-breaker

The main role of a circuit-breaker is to prevent overheating and to prevent fire risks. It limits the current flowing through the electrical wires according to their cross-section (area in mm² of the wire cross-section).

Circuit-breakers are modular devices that protect the electrical equipment in your home. The nature of the circuit to be protected and the cross-section of the electrical wires used determine the size of the circuit-breaker.

The control modules

Your electrical panel can be equipped with a large number of modular devices other than protective devices. This can be, for example, a lightning arrester.

It protects all sensitive equipment against the known and indirect effects of lightning. Generally speaking, it is not a component that is imposed on you, but it is required in areas where there is a high risk of lightning strikes.

An electrical panel can also include lighting management devices, such as a remote switch. It is the equipment that allows to illuminate and switch off the light of the same circuit from several push buttons. They are the ones who operate the remote switch by acting on its coil via their pulses. This causes a change of state of the contacts which then causes the lighting circuit to be switched on.

The day/night switch (also called off-peak/peak time switch) is the energy management device. If you have a contract with the “off-peak” option from EDF, it allows you to manage the cumulus of your home. To do this, it switches on the water heater during reduced-rate periods.

There are many other order modules for which I will devote a detailed article to you in the coming weeks.

Other key elements of the electrical panel

In order for each component of your table to perform its function properly, other elements are essential. Indeed, how are WILDs, circuit breakers and other modular equipment connected? This connection is ensured by the horizontal feeding combs, also called bridging bars.

Two are required for each row of the table, for Neutral and Phase. The electrical panel can also include vertical combs to connect the 30mA differentials.

The last key elements I will mention are the terminals. Depending on the composition of your distribution table, you can have 3 or 1 only. 3 for Neutral, Phase and Earth. However, vertical combs can replace the Phase and Neutral terminals. The main role of the latter is to ensure the connection between the differential switches. On the other hand, the Earth terminal block is essential. It is the one that allows the earthing of electrical circuits.

Finally, all modular devices are attached to the DIN rail of the electrical panel. And to be connected to the electricity grid of the electricity supplier such as EDF, the box is connected to the connection circuit-breaker via the main power supply. It also makes it possible to switch on the general power cut of your home.


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Electrician in Montreal