IEC 60364-5-55:2011 The particular requirements apply to extra-low-voltage lighting installations supplied from sources with a maximum rated voltage of 50 V a.c. or 120 V d.c. For the definition of an extra-low voltage lighting system reference should be made to IEC 60598-2-23. This second edition cancels and replaces the first edition, published in 1999, and constitutes a technical revision. The major technical changes with respect to the previous edition are: - the clause numbering is aligned with the present structure of IEC 60364; - references to LED modules and their particular installation requirements have been introduced; - and requirements for cross-sectional area of conductors are modified.