on a floor of a building , a wiring layout of information circuits which are used by personnel who work at a plurality of blocks , has at each block outlet connectors connected to information devices at the block . an interconnection unit has primary connectors connected to extend devices e . g . telephone exchange or network controller , and secondary connectors . wiring structures each having a plurality of wiring cables connect respective groups of the secondary connectors to respective blocks . interconnection cables detachably and interchangeably connect the primary and secondary connectors at the interconnection unit . to enable efficient and simple re - arrangement for the information circuits , first identification signs , e . g . colors , identify blocks associated with the respective wiring cables , and at the interconnection unit , the secondary outlets connected by one of the wiring structures to one of the blocks are grouped together in space and have associated with them an identification sign which is the same as the first identification sign identifying the block to which they are connected .