A motor circuit requires a disconnecting means capable of opening the circuit to the motor and controller, and it must be lockable in the open position. According to NEC 430.102(A), where must the motor disconnect be located?
- AWithin sight of the motor and its driven machinery.
- BWithin sight of the controller, or within sight of the motor and its driven machinery with specific conditions met.
- CWithin sight of the controller.
- DWithin sight of the motor and the controller.
Show answer & explanationAnswer & explanation
Correct answer: B. Within sight of the controller, or within sight of the motor and its driven machinery with specific conditions met.
NEC 430.102(A) states that a disconnecting means shall be located in sight from the controller location. NEC 430.102(B) further specifies that a disconnecting means shall be located in sight from the motor and its driven machinery. However, the exception to 430.102(B) allows the disconnect to be out of sight from the motor and driven machinery if it is lockable in the open position and meets other conditions (e.g., within sight of the controller, or if the controller is also out of sight, specific conditions apply). The question asks for the location of 'the' motor disconnect, implying the primary one. A disconnect must always be within sight of the controller. If it's also the motor disconnect, it can be out of sight of the motor if lockable and specific conditions are met. Therefore, 'within sight of the controller, or within sight of the motor and its driven machinery with specific conditions met' covers the primary requirements and the flexibility allowed by the code.
Why the other options are wrong
- A. This is a requirement for the motor disconnect, but it's not the only option, especially with a lockable disconnect.
- C. This is a requirement for the controller disconnect, but the motor disconnect has additional location requirements.
- D. This is a common ideal placement, but the code allows for more flexibility with a lockable disconnect from the motor.
Motor Disconnecting Means Location (NEC 430.102)
The motor disconnecting means must be located within sight of the controller. Additionally, a separate disconnecting means must be within sight of the motor and its driven machinery, or the controller's disconnect must be capable of being locked in the open position.
- Disconnect must be in sight of the controller (430.102(A)).
- Disconnect must be in sight of the motor and driven machinery (430.102(B)).
- Exception: Out of sight of motor is permitted if disconnect is lockable open (430.102(B) Ex.).
- Ensures personnel safety during maintenance.
Memory trick: See the control, or see the motor with a lock.