Surge protection devices (SPDs)

Surge protection devices or SPDs are meant for protecting electricity networks and electrical appliances from the overvoltage and pulse currents caused by lightning and switching.

There are three types of SPD. Type 1 and 2, and 1+2 SPDs are used in electricity systems inside buildings (type 1 or 1+2) and in the switchboards of internal wiring systems (type 2).

Type 1 includes lightning-proof SPDs, which can withstand powerful electrical impulses but do not limit lightning impulses sufficiently, for example in home electronic appliances.

Type 2 SPDs limit lightning impulses that have already been limited by type 1, or impulses that occur due to indirect lightning strikes or switching in the electrical system.

Type 1 and type 2 SPDs are mostly installed in the junction box and only a professional electrician may install them. We recommend contacting a professional electrician or a specialist company to find the best solution.

Type 3 SPDs are installed close to the appliance or the socket. They limit overvoltage impulses so that they don't pose any threat to electronic appliances which are in normal working order.

NB! SPDs that can be connected in the socket only work if they have been connected to a three-wire earthed electricity system. Protection devices do not work for electricity systems that have not been earthed. This mostly applies to electricity systems built before 1995. For more detailed recommendations and devices ask an expert electricity products seller.


A UPS is an emergency electrical power source and voltage stabiliser, which provides protection during short power outages of up to ten minutes.

The UPS can guarantee a power supply for up to five minutes for appliances with a wattage of up to 400W, and for as long as 33 minutes for appliances with a wattage of less than 400W. The UPS has a built-in battery that guarantees the power supply for appliances connected to it, and it also protects electrical appliances from any overvoltage caused by lightning or power failures.

NB! We do not recommend connecting a UPS to appliances with electric motors such as fridges, pumps or heat pumps because the start-up current for such electric motors is usually many times larger than the rated current given in their technical documentation. You can find out more about the UPS in electronics and construction shops.

Voltage stabiliser

A voltage stabiliser transforms unstable socket voltage that does not meet the standard of 160V–250V into a stable voltage of 230V. Depending on the manufacturer, the wattage in the voltage stabilisers used in homes ranges between 500 and 2000W.

Voltage stabilisers must not be used to stabilise freezers, electrically operated hand tools, air conditioners, dehumidifiers, food processors and other appliances with electric motors. NB! Before connecting the voltage stabiliser, please make sure whether the electrical appliance already has a built-in voltage stabiliser. Double voltage stabilisation is not permitted for many sensitive appliances! You can find out more about voltage stabilisers in electronics and construction shops.

Residual-current device

A residual-current circuit breaker (RCCB) cuts the power off if a person or an animal comes into contact with non-isolated wires or the live casing of a faulty electrical appliance. An RCCB helps prevent serious electric shocks and save lives, and it also minimises the risk of fire. Residual-current devices are as important as smoke detectors!

Current standards in Estonia state that new electric installations must have residual-current devices. A residual-current device with an operating current of 30mA will protect lives, and you should also install additional protection for:

  • generally used sockets with a nominal current of up to 20 A;
  • portable equipment used outdoors with a nominal current of up to 20 A.

Additional protection must be used in damp rooms, like shower rooms, bathrooms, saunas and kitchens. Install a residual-current circuit breaker and add additional protection.

RCCBs have different operating currents. and we recommend that you consult an electricity specialist to help you make the right choice. As with most other protection devices, you will need to order the design and installation work from an expert electrician or electric company if you want to connect RCCBDs to your electricity system

Lightning protection system

A lightning protection system has an external and internal system.

The external system consists of trapping equipment, mainly a lightning conductor, with down conductors and the earthing system, and it is meant to protect buildings from direct lightning strikes. If a building has an external lightning protection system, it should also have an internal system installed. The main components in the internal system are surge protection devices. As with most other protection devices, you will need to order the design and installation work from an expert electrician or electric company if you want to install a lightning protection system.

Electricity generators

A generator is a device that generates electricity. Depending on the wattage of the generator, you can connect the entire electricity system, a part of it, or just a single appliance which must remain in operation during a power outage.

We recommend you make sure that the wattage of the generator is at least 20–25% higher than the nominal power of your electricity system or electrical appliance, which you will find on the appliance or in its documentation.

If you want to connect the generator directly to the building's electricity system, then you will have to build a separate generator connection point where the protection devices and switches are located.

You must let an electricity company install the generator, because if the generator has not been connected correctly:

  • it can cause a fire;
  • electrical appliances might be damaged by overloads;
  • it is extremely dangerous or even life-threatening for electricians who are fixing breakdowns or doing electrical work in the electricity system at the same time.

NB! Before you turn on the electricity generator, read the user manual and safety instructions very carefully. All safety requirements are mandatory when using generators.