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For elevator circuits, does the electrical interlock offered for Square D safety switches meet the requirements of NEC 620.91(C) for disconnecting the emergency or standby power source from the elevator?

Product Design Features

Product Line:
Heavy Duty and General Duty Safety Switches


NEC requirements


The electrical interlocks provided for use with Square D F-Series safety switches meet the requirements of NEC 620.91(C). NEC 620.91(C) requires the power to the elevator be removed from both the normal and emergency or standby power sources. When a power source is connected to the load side of the disconnecting means, an auxiliary contact shall be positively opened mechanically, and the opening shall not be solely dependent on springs.

The electrical interlock on the switch is driven either by a lever in contact with or by direct contact with the operating mechanism of the switch (dependent on switch ampacity). A spring used on the interlock lever on 30 -100A switches does not function to drive contact state as the switch is operated from a closed to open state.

The electrical interlock contains two separate sets of contacts, and they act opposite of each other - when one set is open, the other set is closed. Turning the safety switch ON and OFF causes these contacts to open and close. To disconnect the control voltage feeding the emergency power circuit, the installer should wire the control circuit to the set of interlock contacts that are normally OPEN when the switch is OPEN (OFF).

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