Electric heating elements

An open coil heater assembly, comprising,

• a metal support member,
• a helically-coiled resistance wire connected to and supported by said support member at a plurality of places,
• an insulator member at each of said places for electrically insulating said resistance wire from said support member, each insulator member being of one-piece molded refractory material and having a portion generally rectangular in transverse cross section to provide generally flat parallel opposed side surfaces,
• said insulator portion having a slot extending inwardly from an end thereof and transversely from one to the other of said opposed surfaces, said slot being sized and arranged to freely pass and receive a portion of the resistance wire between adjoining convolutions to permit said coiled resistance wire to extend transversely of and from said opposed surfaces and whereby said wire portion may be moved to position within said slot without hindrance from the defining walls of said slot,
• at least one of the opposed flat surfaces having a portion inclining transversely from a longitudinal edge thereof and inwardly toward said slot in a direction toward the opposed surface, and such surface having a hook-like projection extending therefrom to overlie the wire portion within said slot and thereby restrict its withdrawal from said slot.