| AC voltage the r.m.s. value of which does not exceed 50 V or ripple-free DC voltage the value of which does not exceed 120 V, between conductors, or between any conductor and reference earth, in an electric circuit which has galvanic separation from the supplying electric power system by such means as a separate-winding transformer
NOTE 1 – Maximum voltage lower than 50 V AC or 120 V ripple-free DC may be specified in particular requirements, especially when direct contact with live parts is allowed.
NOTE 2 – The voltage limit should not be exceeded at any load between full load and no-load when the source is a safety isolating transformer.
NOTE 3 – Ripple-free qualifies conventionally an r.m.s. ripple voltage not more than 10 % of the DC component; the maximum peak value does not exceed 140 V for a nominal 120 V ripple-free DC system and 70 V for a nominal 60 V ripple-free DC system.