Backing plate and electrical switch housing for use with C purlins, Z purlins and the like

摘要

A C purlin 10 with a standard insulated power cable 11 coming in to a cylindrical hollow body 12 projecting through a hole 13 to provide a cable grommet as effectively a T junction through the metal purlin. On the top side 14 of the C purlin 10 is a housing 14 which is secured at the back by screws at 15 and 16 and at the front through screw hole 17 and 18 . All this is moulded plastics so it is all insulating. The cylindrical body 12 includes an outer wall 18 which is the same or slightly smaller diameter than the hole 13 in the C purlin so that it fits into place but it has an upper collar which is of greater diameter so that it can simply slip into and hang from the hole 13 in register with the underside edge 20 of the collar sitting atop the upper side of the C purlin.