The interlock receptacle switches offer is built upon the robust Heavy Duty Safety Switch platform that has led the industry for over 100 years. These switches are fitted with Appleton Powertite ™, Crouse-Hinds Style 2 Arktite ™ or Hubbellock ™ receptacles. The switches support three-phase four-wire applications. The fourth wire is connected to the switch equipment grounding terminal and is not a solid neutral termination.