How can I protect my electrical appliances from voltage fluctuations?

Everyone is familiar with the phenomenon of a flickering lamp in the living room. This phenomenon, also known as "flicker", is caused by voltage fluctuations in the electrical network. In general, this is not a problem. Your network operator limits its effects with protective measures. 

But things are changing. Renewable energies, which can sometimes be irregular, are likely to cause power surges. Equipment that requires high power, such as charging stations or heat pumps, can in turn create power dips. All of this makes it more difficult to guarantee the stability of the grid.

There are several complementary solutions to protect your appliances against these variations. For maximum security, a "cascade" approach is generally used.

This is the first line of defence. Surge protectors (also known as SPDs, or Surge Protective Devices) are installed directly in your electrical panel. They resemble conventional circuit breakers, but with specific visual characteristics.

They generally occupy the space of 2 circuit breakers for a single-phase installation, and 4 for a three-phase installation. The central part can often be removed and replaced after a lightning strike without dismantling all the wiring.

On the front, there is a small coloured window: green (everything is fine, the device is protecting) or red (the cartridge needs to be replaced).
There are several types of surge protector, depending on whether or not your building has a lightning rod.

• Type 1: Essential if your building has a lightning rod. It handles very powerful direct lightning strikes.
• Type 2: This is the most common type in homes. It protects against indirect surges (lightning striking nearby) and voltage fluctuations in the grid.
• Type 1+2: Combined models are available to simplify installation.

These devices protect your connected appliances individually. They complement the main surge protector but do not replace it in the event of a major impact.

Check their absorption capacity

Do not rely on the physical size of the object to determine its protective capacity. A high-end power strip can provide much better protection than a low-end individual socket.

Check the energy rating on the packaging:

• Entry-level (< 500 joules): Protects against everyday micro-voltage spikes (power line interference). Suitable for small appliances.
• Mid-range (500 to 1500 joules): Offers serious protection against indirect power surges. Ideal for standard TVs and computers.
• High-end (> 2000 joules): Capable of withstanding significant and repeated voltage spikes. Recommended for very expensive equipment or areas where the mains supply is unstable.

Other tips for making the right choice

• Check for a ground connection: None of these devices will work without a good ground connection.
• Check the "Protected" indicator light: The internal components of power strips wear out with every small power surge they absorb. If the indicator light goes out, the protection is no longer working (even if the power is still flowing).
• Choose recognised brands: For critical equipment, look for specialist brands (Eaton, APC, Schneider Electric, Legrand).

Lightning does not only travel through electrical cables, it can also travel through data lines.

• RJ45/ADSL surge protector: Protects your internet box and landline telephone against power surges from the telephone line.
• Coaxial surge protector: Installed between the antenna (or satellite dish) and the television to prevent lightning from travelling down the antenna cable.

Your home is connected to the low-voltage grid, which distributes electricity at a voltage of 230 volts. 

To prevent breakdowns or damage to electrical appliances, standards set limits on voltage deviations. Electrical appliances are normally designed to function properly within these limits.

To ensure that your equipment can withstand these variations, make sure you choose devices with the CE marking when purchasing. This marking guarantees that they comply with European safety standards.

Special case: inverter decoupling

Compliance with these limits is particularly important if you generate your own electricity using solar panels. In the event of high feed-in to the grid, the voltage may rise.

If the distribution network voltage exceeds the threshold of 253 volts, the inverter for your solar panels will automatically shut down. This is known as a “inverter decoupling”. This safety feature is activated to protect your installation and the grid from excessive overvoltage.

Contrary to popular belief, an undervoltage (voltage drop below the standard 230V) can be just as devastating as a surge.

• For motors: Electric motors are designed to provide a certain amount of "work" (torque). If the voltage drops, the motor must compensate by drawing more current to maintain its power. This excess current causes the windings to heat up abnormally.
• For electronics: Modern devices use sophisticated switching power supplies. The device's power supply will attempt to regulate the internal voltage despite the low mains voltage. This stresses the capacitors and transistors beyond their design limits, drastically reducing their service life.