The Institute for Standardization of Bosnia and Herzegovina, through its Technical Committee BAS/TC 8 Insulation Coordination, High Voltage Testing and Instrument Transformers, has adopted the third edition of the Technical Specification BAS CLC/TS 61643-22:2025, Low-voltage surge protective devices – Part 22: Surge protective devices connected to telecommunications and signaling networks – Selection and application principles, by the translation method. This is a translation of the identical English version of CLC/TS 61643-22:2015, which is a modified version of IEC 61643-22:2015.

BAS CLC/TS 61643-22:2025, which is part of the IEC 61643 series, describes the principles for the selection, operation, location, and coordination of SPDs (Surge Protective Devices) connected to telecommunications and signaling networks with nominal system voltages up to 1000 V r.m.s A.C and 1500 V DC. The document also addresses SPDs that incorporate protection for signalling lines  and power lines in the same enclosure (so-called multiservice SPDs).

The document is a guide for the application of SPDs to telecommunications and signal lines and those SPDs which jave telecom or signalling SPDs in the same enclosure with power lines SPDs (so called multiservice SPDs). Definitions, requirements, and test methods are given in IEC 61643-21. The decision to use SPDs is based on the analysis of the risks that are seen by the network or system under consideration. Because telecommunications and signaling systems may depend on long lenghts of wire, either buried or aerial, the exposure to overfoltages from lightning, power line faults, or power line/load switching can be significant. If these lines are unprotected, the resultant risk to Information Technology Equipment (ITE) can also be significant. Other factors that may influence the decision to use SPDs are local regulators and insurance stipulations.

The following variables should be reviewed when attempting to attain proper coordination:

• waveshape of the impinging surge (impulse or AC);
• ability of the equipment to withstand overvoltage/overcurrent without damage;
• installation, e.g., distance between SPDs and between SPDs and the ITE;
• SPD voltage-protection levels.

The original texts of the standard were prepared by the International Electrotechnical Commission (IEC) Technical Committee IEC/TC 37, Surge Arresters.