Surge arrester

What is a surge arrester


The surge arrestersalso called SPD (from the English Surge Protection Device) are protection devices against atmospheric discharges e le overvoltages of the installations.

They therefore protect against sudden changes and electrical peaks coming from the electrical supply, or from atmospheric phenomena such as lightning.
Not having it would mean exposing oneself to possibilities serious damage to home or workplace devices.


The problem of overvoltages concerns both the civil sector and the industrial or tertiary sector.

In this article we will try to explain also to non-experts, theimportance of surge arresters and how to choose the ones that best suit your needs.

The use of surge arresters is regulated by standards CEI 81-10 (2006-04) and CENELEC HD 60364-5.534 (2007-02).

Types of surge arresters on the market


Starting from the basics, there is not just one type of surge arrester.
These in fact are divided into three macro categories.


Surge arrester type 1: this device will be installed in areas where usually dangerous atmospheric phenomena such as temporal e lightning they are frequent (for example in the mountains).

In this specific case the appliance will be installed in the electrical panel and will be able to withstand several sudden changes without being damaged. The discharge takes place in 350 microseconds, so as to prevent excess energy from reaching the system.

Vikye type 2 arresterVikye type 2 surge arrester

Surge arrester type 2: this SPD is the one that will protect the plant from sudden changes e peaks which can be caused by maintenance works of the line by the operator.

Installation is recommended, especially in densely populated city areas.
A combined assembly between various types of arresters for all-round protection.

Finder type 3 arresterFinder type 3 surge arrester

Surge arrester type 3: in this category are those devices that offer a superior protection. In this specific case, the installation will take place directly at the electrical sockets in the home or office.

How to choose the surge arrester


At this point we must understand how to read the data present on the surge arrester that you want to buy. A premise, however, is a must.

The installation of these devices should never be done alone, but relying on always to one professional. Obviously, people who have a solid knowledge base on the subject are an exception.

Finder unloader specificationsFinder surge arrester specifications

In order to make the best choice, in any case, it is necessary to use the “plate data“Of each type of discharger (see photo above) and that is all its own specifications.

The most important are:

  • Nominal tension (Un): indicates the rated voltage of the power supply system;
  • Maximum continuous voltage (Uc): indicates the voltage value below which the surge arrester does not work;
  • No-load voltage (Uoc): this parameter is peculiar to Class III SPDs and corresponds to the peak value of the no-load voltage of the combined type test generator capable of simultaneously delivering a current with a waveform of 8/20 micro seconds;
  • Nominal discharge current (In 8/20): indicates the maximum value that the arrester can withstand before being damaged;
  • Level of protection voltage (Up): represents the maximum voltage value that persists across the overvoltage arrester during its intervention.

Precautions for a perfect installation of the surge arrester


As mentioned, for the installation of a surge arrester it is better to contact qualified personnel since if it is performed incorrectly there is the risk of making it completely useless the operation.


It is necessary first to check well i connections to the equipotential bar and also the length of the cables which must be no more than half a meter.

Also check that the products purchased are all a rule of law and suitable for the type of home where they will be installed.

Always rely on a professional
The electrical and electronic systems that the SPD will protect are many, whether they are homes or offices. Going to save a few euros on their installation exposes you to the risk, in the event of a power outage, of going to pay good money in various repairs.

It will therefore be fundamental to protect 360 ° everything through the surge arresters for which it is essential to have a state of the art installation that is suitable for standard CEI section 534.

Some examples of surge arresters on the market


There are two options to purchase a suitable surge arrester.
The first is to contact a specialized shop; the second will be to make purchases on Amazon.

For example, the Type 7P2282750020 Series 7P surge arrester from Finder from 275 Volts it is suitable for installations in areas where atmospheric discharges would endanger the electronic material.


Alternatively, the low voltage discharger of the Vikye has interesting features for installation e maintenance thanks to its modular design, which makes everything much easier. In fact, this product adopts guide rail installation.

I prices of surge arresters, without considering any offers that are sometimes found on Amazon, fluctuate from 250-300 euro for type 1, 50-70 euro for type 2, up to i 20-25 euro of type 3.


Source: LAVORINCASA.it by www.lavorincasa.it.

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