Abstract: Contactors and housings therefor wherein the contactor is provided with blow-out coils brought into circuit by the arc; arc extinguishers; and fuses in series with the contacts; a closing and holding magnet for operating the contacts; anti-single-phasing operation to open the contacts in response to overload interruption by a fuse; the housings being of modular arrangement to form a uniform control center and being provided with racking means for inserting and removing the contactors with the door closed; and means for protecting the operator including the closing off of access to at least the line bus when the contactor is racked out and disabling the racking mechanism when the contactor contacts are closed.