Each elevator shall have a means for disconnecting all ungrounded main power-supply conductors for each unit, _____.
a) excluding the emergency power system
b) including the emergency or standby power system
c) excluding the emergency power system if it is automatic
d) and the power supply may not be an emergency power system
See answer and applicable Code reference
The correct answer is: b) including the emergency or standby power system
Emergency and standby power requirements for elevators are outlined in Sec. 620.91 of the 2011 NEC. As per 620.91(C), "The disconnecting means required by 620.51 shall disconnect the elevator from both the emergency or standby power system and the normal power system. Where an additional power source is connected to the load side of the disconnecting means, which allows automatic movement of the car to permit evacuation of passengers, the disconnecting means required in 620.51 shall be provided with an auxiliary contact that is positively opened mechanically, and the opening shall not be solely dependent on springs. This contact shall cause the additional power source to be disconnected from its load when the disconnecting means is in the open position."