Damage prevention

Grid disturbances can be caused by weather conditions and works on the grid. By knowing the effects that disturbances and malfunctions can have on the equipment, you can take measures to prevent damage. We also recommend insuring your property and choosing an insurance package that also covers the risk of damage to electrical equipment.

Common causes of disruption

  • over voltage pulses due to thunder and power grid connection
  • voltage drops due to switching operations, short circuits and starting of electrical equipment
  • interruptions and scheduled maintenance
  • non-compliant supply voltage
  • Read more

    Observe the CE marking on electrical equipment

    For safety reasons, observe the CE marking on electrical equipment, which is the mandatory safety marking for appliances sold in the European Union. If an electrical appliance does not have the CE mark, the use of this appliance may be dangerous in our electrical system.

    Impact on electronic devices

    Voltage fluctuations and power cuts affect devices in different ways. Sensitive electronic devices as well as other property may be damaged.

    Read more about the impact of disturbances

    How to protect your electrical appliances

    During lightning storms, you can best protect your equipment by unplugging it beforehand. Additional protection devices can be installed for daily protection of electrical equipment. Order the installation of more complex equipment from a professional electrician.

    Lightning protection system

    Helps in case of over voltage caused by lightning or switching operation in the power grid.

    Surge arresters

    Protects electrical equipment from overvoltage and surges.


    Provides protection in the event of short-term power outages.

    Voltage stabilizer

    Reduces voltage fluctuations by making substandard voltage more stable.

    Engine protection

    Engine circuit breaker. Protects devices with a 3-phase electric motor in case of phase loss or phase voltage drop.

    Voltage control relay

    Protects electrical equipment from both overvoltage and undervoltage.

    Residual-current device

    The RCD protects the electrical equipment or circuit in the event of an insulation failure by switching off the power in the event of an emergency, helping to prevent more serious electrical accidents.


    Helps to keep emergency power supplies working in the event of a long-term power outage.

    Read more

    The impact of disturbances

    Over voltage can present a biggest risk to supplies for electronic devices and sometimes also the devices connected to it (TVs, digital boxes, computers, etc.) Although the electrical system of Elektrilevi is equipped with overvoltage limiting devices, they do not always protect against possible impulse overvoltage due to lightning and switching. Therefore, we recommend that you add additional protection to sensitive electronic equipment in your domestic electrical system.

    Possible causes of over voltage:

  • lightning strike
  • switching operations in the electricity grid
  • Voltage drops and voltage fluctuations can damage particularly sensitive electrical and electronic equipment, as well as their power supplies. In addition, the constant flashing of lights reduces the life of electric lamps and interferes with vision.

    Possible causes of voltage drops and fluctuations:

  • switching operations in the electricity grid
  • power line failures, such as fallen trees, icing, etc.
  • starting high power electric motors
  • proximity to major manufacturing plants and workshops
  • Planned interruptions are required for the repair and maintenance of an outdated power grid as well as for the construction of a new grid. When we are planning such interruption in your area, you will be notified well before. Interruptions or sudden power outages can be short and long lasting. Short-term interruptions (up to 3 minutes) are more common in cities where it is possible to quickly restore power through another line in the event of a malfunction. Such short-term power cuts have the greatest impact on electronic equipment.

    Prolonged power cuts (more than 3 minutes) are more common in rural areas where it takes longer to restore power. This is due to overhead lines used in rural areas which performance is affected by extreme weather conditions such as heavy snow, trees breaking in strong winds, icing on cables, low or high air temperatures and other natural influences. Forest and excavation work near the power lines may also cause malfunctions.

    In the case of a three-phase power supply, there are sometimes situations where there is no complete power failure but no voltage in one or two phases. In this situation, most home electrical appliances may work quite normally, but appliances powered by a 3-phase electric motor such as a power saw or pumps cannot be started. At worst, the loss of phase(s) can lead to the destruction of these devices.

    Characteristics of distribution networks

    Under normal operating conditions, except in the case of outages, slow changes in the supply voltage may not exceed ±10% of nominal voltage Un.

    In distribution networks not connected to the transmission networks or for special long distance users of the power network, slow changes in the supply voltage may not exceed +10% / –15% of nominal voltage Un. Users of the power network have to be informed of these circumstances.

    NOTE 1

    The actual power consumption of individual users of the power network is not fully predictable in amount or time. Due to this, power networks are generally planned based on probability. If after a complaint by a operator of the power network, measurements according to section show that the supply voltage value deviates from the limits given in section, causing negative results for the user of the power network, the operator of the power network must in cooperation with the user(s) of the power network take corrective measures according to the risk assessment. Temporarily, during solving the problem, slow changes in the supply voltage must stay between +10% / –15% of nominal voltage Un, unless otherwise agreed with the users of the power network.

    NOTE 2

    In accordance with the relevant product and installation standards and the implementation of standard IEC 60038, the current using equipment of the user of the power network is usually planned to tolerate deviations of supply voltage ±10% of the power network's nominal voltage, which is sufficient for most supply conditions. In general there is no need to plan current using equipment to tolerate larger voltage deviations.

    NOTE 3

    Considering various national characteristics of power systems, e.g. power limit in a connection point and/or power factor limits, the designation "special long distance user of the power network" can differ between countries. Source: EVS-EN 50160:2010 "Voltage characteristics of electricity supplied by public distribution networks" Full text of the standard can be read at the website of the Centre for Standardisation.

    How to protect your electrical appliances

    Helps in case of overvoltage due to lightning or switching operations in the grid.

    The lightning protection system consists of an external and an internal lightning protection system that must be used simultaneously.

    If the building has an external lightning protection system, it is important to install an internal system, which usually contains surge arresters.

    To install a lightning protection system, always order the design and installation work from a professional competent electrician or electrical work company.

    Protect electrical equipment from impulse overvoltage.

    Surge arresters help protect electrical networks and equipment from overvoltage caused by lightning and switching operations.

    Surge arresters are divided into types 1, 2 and 3.

    Surge arresters of types 1 and 2 and 1 + 2 are used in the electrical supply of buildings (type 1 or type 1 + 2) and in the distribution boards of internal wiring (type 2). Always order design and installation work from a competent electrician or electrical work company.

    Type 3 surge arresters are installed directly in front of the equipment, ie in sockets. They help to eliminate the danger caused by overvoltage pulses. Contact the vendors of the respective products to find suitable devices.

    The UPS is a backup power supply and voltage stabilizer that provides a solution in the event of short-term power outages.

    The UPS includes a battery that provides power to the connected equipment even during interruptions.

    It is not recommended to connect devices that run on an electric motor, such as a refrigerator, pump, heat pump, etc., to the UPS, as the starting current of these devices is usually several times higher than the operating current. Contact your dealer for more information on UPS.

    The voltage stabilizer converts the socket out-of-standard voltage to a stable 230V voltage.

    Voltage stabilizers can not be used to stabilize the supply voltage of refrigerators, washing machines, heat pumps, power tools, and other devices powered by an electric motor.

    Before connecting the unit to a voltage stabilizer, make sure that your electrical equipment has a voltage stabilizer already built-in by the manufacturer. For many sensitive devices, double voltage stabilization is prohibited. Contact your dealer for more information.

    Engine protection switch.

    An additional motor circuit breaker can be used to protect equipment with a 3-phase electric motor (eg machine tools, certain types of heat pumps, etc.).

    The engine protection switch is helpful if the device itself does not have the corresponding protection.

    Engine protection also protects in the event that one phase switches off unexpectedly.

    Protects electrical equipment from overvoltage and undervoltage.

    The use of a voltage control relay is recommended in case of using electrical equipment that is sensitive to voltage fluctuations. The appliance is also helpful if there are frequent faults in the external power supply at the point of consumption.

    The voltage control relay checks the voltage for compliance with the norm, the minimum and maximum of which are determined by the device to be protected. When the voltage exceeds the permitted range, the voltage control relay switches off the device (s). When the voltage returns to normal, the relay will turn the unit(s) back on.

    Always order voltage control relay installation work from a competent electrician or electrical company.

    The RCD switches off the power in the event of an emergency, helping to prevent more serious electrical accidents.

    RCDs are as important in the household as smoke detectors. The RCD switches off the power in the event of an emergency, helping to prevent a serious electric shock. It saves lives and reduces the risk of fire.

    The RCD is helpful if a human or animal comes into contact with malfunctioning electrical equipment housing which is under voltage.

    Be sure to use extra protection in all wet rooms, such as the shower, bathroom, sauna and kitchen.

    As with other protection devices, the design and installation of the RCD must be ordered from a competent electrician or electrical company to connect it to the electrical system.

    In the event of a long-term power failure, an electricity generator will come to the rescue.

    A generator is a stand-alone electrical generating device that can be used as power supply and depending on the capacity, either the whole electrical system, a part of it or a single device which operation is most critical during a power failure, can be connected to it. When choosing a generator, it is important to ensure that its power is at least 20-25% higher than the rated power of the electrical system or electrical equipment.

    In order to connect the building to the electrical system, it is necessary to build a separate connection point for the generator with fuses and a switch.

    When using the generator, great care must be taken to comply with safety requirements.

    An generator which is incorrectly connected to the electrical system, is dangerous and can cause a fire. It can also damage other electrical equipment due to overcharge or be life-threatening for electricians who rectify faults in the electrical network or perform electrical work.

    Order the design and generator installation work from a professional electrician or electrical company.