IEC 60876-1:2012 applies to fibre optic switches possessing all of the following general features: - they are passive in that they contain no optoelectronic or other transducing elements; - they have one or more ports for the transmission of optical power and two or more states in which power may be routed or blocked between these ports; - the ports are optical fibres or fibre optic connectors. This fourth edition cancels and replaces the third edition published in 2001. It constitutes a technical revision. The changes with respect to the previous edition are to remove quality assessment procedures and to reconsider definitions. Key words: fibre optic switches