EN 50556:2011 – Road traffic signal systems
5 Safety
5.1 Electrical safety
5.1.1 General
5.1.1.1 Introduction The Road Traffic Signal System shall conform to HD 384.4 series. This subclause deals with the additional requirements for Road Traffic Signal Systems.
5.1.1.2 Criteria − Leakage current
5.1.1.2.1 Road Traffic Signal Systems Class T1: For Road Traffic Signal Systems, leakage current protection facilities conforming to HD 384.4.41 shall be fitted. Earth leakage circuit breakers conforming to EN 61008 series for nominal currents 20 % greater than the expected current and nominal leakage currents ≤ 0,3 A shall be installed. Class T2: No requirement for leakage current protection facilities for the whole system, however the customer may request facilities as class T1.
5.1.1.2.2 Maintenance equipment supply To conform with HD 60364-4-41, an earth leakage circuit breaker conforming to EN 61008 series with nominal leakage currents ≤ 0,03 A shall be installed.
5.1.1.3 Earthing
5.1.1.3.1 General This subclause applies to the installation or part of the installation which is class I conforming to EN 61140.
5.1.1.3.2 Protective earth conductor (PE) The system shall conform to HD 60364-5-54. Protective earth conductors shall connect together all conductive parts and the PE terminals throughout the system. They shall either be created by conductors in a cable or by separately installed wires and/or construction parts. In controllers the PE conductors shall be connected to the PE terminal / earth bus bar. NOTE Metallic bodies which, by virtue of their location or smallness, cannot be touched or are unlikely to become live should be designated excluded devices, i.e. they need not be connected to the PE conductor.
5.1.1.3.3 PE wiring of external equipment NOTE 1 Examples of external equipment are poles, signal heads and detectors. The system shall be classified according to the following methods. Accessible conductive parts shall be connected to the PE conductors incorporated in the cables or a separate PE cable. NOTE 2 Armouring of cables may also be used as PE conductors where the cable construction permits.
5.1.1.4 Enclosure The enclosure shall provide the mechanical protection to IK07 (see EN 50102) with the following criteria: No damage shall occur to the equipment contained within the enclosure and the equipment shall continue to operate to its specification. There shall be no degradation of the IP rating of the equipment. Class V1: Enclosures shall provide protection to IP44. When the manual panel is open, the protection provided shall be to IP42. When the enclosure is open the protection shall be to IP20. Class V2: Enclosures shall provide protection to IP54. When the manual panel is open, the protection provided shall be to IP23. When the enclosure is open the protection shall be to IP21.
EN 50556-2011