USCG Exam PracticeMotor controllers and remote control
Under 46 CFR §111.70-7, when a control, interlock, or indicator circuit cannot practicably be energized from the load side of the disconnect device and the circuit voltage exceeds 24 volts, one permitted alternative is to use a disconnect device actuated by the opening of the controller door. Which additional requirement applies when this arrangement is used on a vital auxiliary motor controller?
- A. The disconnect device must be rated for the full motor running current rather than the control circuit current
- ✓ A nameplate must be affixed to the controller door warning that opening the door will trip a vital auxiliary off-lineCorrect
- C. A fixed sign must be placed on the exterior of the main disconnect device warning the operator to open both devices
- D. The two independent disconnect devices must be adjacent to each other and interlocked mechanically
Why B is correct
46 CFR §111.70-7(d)(2) requires that when a door-actuated disconnect is used for vital auxiliary circuits, a nameplate must be affixed to the vital auxiliary motor controller door warning that opening the door will trip a vital auxiliary off-line. Option C describes the requirement for the separate independent disconnect device arrangement under §111.70-7(d)(1), not the door-actuated arrangement.
Cited:46 CFR §111.70-7