Decoding your home’s electrical panel

What is an electrical panel, and what is it used for?

Although we colloquially call it the electrical panel, its technical name is the General Control and Safety Panel. Its precise functions are to control electrical installations and to protect both people and the devices that are connected to the network.

How a home electrical panel works

The electrical panel is primarily responsible for distributing the energy and electrical power to the various connected devices. For this reason, if the maximum power capacity of the installation is exceeded, an electrical overload occurs, which leads to a short circuit. This is simply a safety measure of the electrical panel itself; it cuts off the electricity supply to prevent overheating and avoid further damage.

Main components of the electrical panel

Power control switch (ICP)

If the electrical panel had a boss, this would be the PCS, or Power Control Switch. It is placed in the first position inside the electrical panel, before the Automatic General Switch (AGS), which we’ll find out more about later on.

The PCS is in charge of cutting the electrical supply upon command more power than has been ordered, or in cases of overload or short-circuit, in order to avoid damages to the installation.

In some cases, the PCS is separated from the rest of the switches, with its own cap and seal (in the case of an old panel without a remote-controlled management system). This is so that it is not handled, replaced or bridged, given that any of these actions would mean defrauding the system. In new meters, the PCS is integrated into the panel itself, so it’s not necessary to take measures to prevent it from being handled.

“It checks the power you have ordered, and increases it if the PCS often shuts off”.

Main automatic switch (MAS)

The Automatic General Switch is an element only present in recently-installed electrical panels. If your electrical panel is old, you will not find one inside it. Its function is to cut off the electricity for the entire building in the event of a short circuit or a power overload, whether due to a large number of domestic appliances turned on or because of a short circuit.

The AGS monitors that the installation’s maximum limit is not exceeded. You could have ordered 10 kW of power, but if your installation is not equipped to handle more than 6 kW, it will serve no purpose, given that the AGS will shut off when those 6 kW are exceeded.

“Do not turn on too many domestic appliances at the same time, and try not to purchase apparatuses with a high energy qualification”.

Surge protection device (SPD)

This is another item that is obligatory in newly installed electrical panels in order to enhance safety. The surge protector, as its name indicates, protects the home’s electrical apparatuses from being damaged by power surges regardless of their nature.

These voltage peaks may be caused, for example, if lightning strikes during a storm, and may cause damage to the equipment, to the installation and even to people. In the event of a surge, the SP will act as a shield deviating the current to the earth connection, thus avoiding damage to electrical appliances.

Residual current device (RCD)

The Differential Switch is different from the others. It is easily recognised because it has a swivel lever with it, more commonly called a lock screw. This element protects the installation against current leakages, preventing a “spark” (or something worse still) if we touch a domestic appliance with a loose cable. That’s why, if at any time, the DS shuts off, it’s because a current leakage occurred due to an anomaly in the installation or a defective domestic appliance.

As a general rule, there tends to be a differential for each electrical installation, but depending on the size of the property, there may be two or three to control the different areas of the premises.

Miniature circuit breakers (MCBs)

These switches separately control the supplying of electricity to different domestic appliances and electric circuits: washing machines, lighting, refrigerators, outlets, etc. They are always together. They are inseparable, like good siblings, and if they detect an excess consumptionin one part of the home, the switch concerned disconnects automatically. Thus, only that area is left without electricity, and not the rest of the property.

Like the PCS and AGS, they are magneto-thermal circuit breakers and serve to cut off the electricity manually or automatically, and independently of the apparatuses that depend on them in the event of shortcircuiting or overloading.

SPSs are also useful for construction or maintenance tasks, giving the opportunity to deprive a certain part of the installation of electricity without having to disconnect the entire supply.

“Keep the labels that indicate the circuit or domestic appliance that is controlled by each switch. If they come loose, replace them with new ones”.

Home electrical safety tips

• Never touch the electrical panel with wet hands or in humid conditions.
• Keep the panel accessible and free of obstacles.
• Label each MCB clearly so you know which area it controls.
• Make sure cables and outlets are in good condition.
• Avoid overloading outlets with multi-plugs or power strips.

When should you check or replace the electrical panel?

It’s recommended to inspect your electrical panel every five years in residential homes, or sooner if you experience frequent outages, renovations, or add new installations. If the panel is more than 20 years old, it’s advisable to replace it with one that meets current standards, including devices such as the MAS and SPD. A certified technician can assess its condition and recommend improvements.

What’s the difference between an RCD and an MCB?

The RCD (residual current device) protects people from electric shocks caused by current leakage. If it detects electricity flowing toward the ground, it cuts the power to prevent accidents. On the other hand, MCBs (circuit breakers) protect electrical circuits from overloads and short circuits. Each one controls a specific area or appliance, while both automatically disconnect when consumption exceeds safe limits.

What if the RCD won’t reset?

If the RCD can’t be reset, there’s likely an active current leakage. Disconnect all electrical appliances and try resetting it again. If it still doesn’t work, reconnect devices one by one to find out which one is causing the fault. If you can’t locate the issue, call a professional to inspect the installation.

Why does the power trip frequently?

The most common causes are:

• Consumption exceeding the contracted power.
• Faulty or improperly connected appliances.
• An old or poorly maintained electrical installation.
• Current leakage or moisture inside or near the panel.

If outages happen frequently, inspect the electrical panel and consider increasing the contracted power or upgrading the installation.

Can the electrical panel’s capacity be expanded?

Yes. If you plan to install new appliances, air conditioning, solar panels, or smart home systems, your current panel may not have enough capacity. Expanding it allows you to add new protected circuits and adapt the installation to your needs. This task requires a licensed installer, who will assess the total load and ensure compatibility with the rest of the system.

As you've seen, the electrical panel is an element that seems complicated, but isn't as complicated as it seems. In addition, it will be very useful to you from now on, given that operating it is very simple and intuitive.