In the other countries are these questions usually determined by relevant national directions. Mounting of the overvoltage protection devices solves most related problems and sufficiently protects electronics against influence of overvoltage spreading through galvanic routes. Nowadays it is necessary to abide internationally recognized standard EN 61 643-11 which characterizes stages of overvoltage protections and their tests. Other standards relating to this are being prepared (for example the revisions of overvoltage protection devices).
Because nowadays there is considerable assortment of SPDs with accompanying documentation according to DIN VDE 0675 or DIN VDE 0110 in the Czech Republic, it is advisable here to make a comparison of basic segmentation of SPDs according to these standards and standards obligatory in the Czech Republic, in particular IEC 664-1/CSN 33 0420-1. The standard EN 61 643-11 obligatory in the Czech Republic divides SPDs into stages (1st, 2nd and 3rd) and classes (I, II and III), whereas the standard DIN VDE 0675 divides SPDs into classes (A, B, C and D). The class A arresters are designed for protection of overground LV power system outside of the protected objects. The class B, C and D arresters are designed for usage at the boundaries LPZ 0→1, 1→2 and 2→3. On the other hand the standard DIN VDE 0110 states the definition of overvoltage category, which had been taken up by the standards IEC 664-1/CSN 33 0420-1. These standards define classification of LV power system into four categories (IV, III, II, I) and define so-called maximal impulse withstand voltages (protection levels), permitted for connected appliances. (For example overvoltage at input of distribution TNC 230/400V/50Hz must not exceed 6kV level, it must not exceed 4kV behind the main switchboard, it must not exceed 2,5kV at outputs from subdistribution switchboards and 1,5kV in the part designed for connection of protected appliances to fixed installation.)
Classification comparison of particular LV power system (acc.to EN 61 643-11, CSN EN 61 643-11, DIN VDE 0110, IEC 664-1/CSN33 0420 and DIN VDE 0675) relating to protection levels of surge protection cascade and to zone division acc. to CSN EN 62 305 and IEC 1024-1. Interesting is a similar comparison of these classifications of low voltage network system (LV) sections owing to the overvoltage cascades protection stages in the building electric installations based on the oversea C62.41.2 – 2002 standard ANSI/IEEE (American National Standard Institute/Institute of Electrical and Electronics Engineers). This standard devides 1st, 2nd and 3rd SPD classes into C, B, A categories (Location Categories). Nevertheless, C category is classified into 2 levels (low, high) according to so-called „exposure degreeses“ resulting from isokeraunic maps of “storms activity“ levels.