IEC 60364-7-717:2009 is applicable to mobile or transportable units. For the purposes of this standard, the term 'unit' refers to a vehicle and/or mobile or transportable structure in which all or part of an electrical installation is contained. Units are either of the mobile type or of the transportable type. Examples are units for television and broadcasting, medical services, advertising, fire fighting, using special information technology, units for disaster relief, catering units and the like. The requirements of this standard also apply where two or more units are connected together to form a single electrical installation. This second edition cancels and replaces the first edition published in 2001 and constitutes a technical revision. The main changes with respect to the previous edition are as follows: - The scope has been improved, providing more detail; - The content of Clause 717.41 has been updated following the new edition of IEC 60364-4-41; - Clauses concerning protection by automatic disconnection of the supply and additional protection have been introduced; - All figures have been updated.