This International Standard specifies the requirements for the design, construction and installation of the types of d.c. and a.c. electrical systems described below, either individually or in combination. a) low-voltage alternating current electrical systems which operate at nominal voltages of less than 250 V single phase and extra-low-voltage direct current (d.c.) electrical systems which operate at nominal potentials of 50 V d.c. or less on small craft. b) Single-phase alternating current systems which operate at a nominal voltage not exceeding a.c. 250 V. It is noted that IEC 60092-507 applies to recreational craft of less than 24 m hull length in respect of three-phase alternating current installations which operate at a nominal voltage not exceeding a.c. 500 V. This standard does not cover the following: electrical propulsion circuits exceeding 50 V d.c.. which are addressed by ISO 16315; Any conductor that is part of an outboard engine assembly and which does not extend beyond the outboard engine manufacturers supplied cowling. Additional information to be included in the owner's manual is listed in Annex B.