Part 11 – Sizing Disconnecting Means for Motor & Controller
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10 Questions
Question 1 of 10
Which value should be used for sizing a motor's disconnecting means according to the article?
The article states FLC from NEC tables is used for sizing the disconnect, conductors, and short-circuit protection, while FLA is for overload protection.
Question 2 of 10
What is the requirement if a disconnecting means for a motor rated at 1,000V or less is not within sight of the motor?
Per 430.102(B)(1), if not in sight, a second lockable disconnecting means is required within 50 feet and within sight of the motor.
Question 3 of 10
For a stationary motor rated at 1/8 HP or less, what can serve as the disconnecting means?
According to 430.109(B), the branch circuit OCPD is permitted to serve as the disconnecting means for stationary motors 1/8 HP or less.
Question 4 of 10
What is the minimum current rating requirement for a disconnecting means for a single motor rated 1,000V or less?
Per 430.110, the current rating must be at least 115% of the motor's full-load current (FLC).
Question 5 of 10
When using a general-use AC snap switch as a disconnect for a motor rated 2 HP or less, what is the maximum allowable FLC relative to the switch's ampere rating?
The motor's FLC must not exceed 80% of the switch's ampere rating, meaning the switch must be at least 125% of the FLC.
Question 6 of 10
Which of the following is NOT listed as a permitted type of motor disconnect in 430.109(A)?
Standard light switches are not among the seven types of disconnects listed in 430.109(A)(1) through (7).
Question 7 of 10
If a motor's FLC is not covered by the standard NEC tables, what value should be assumed for the locked rotor current (LRC)?
The article states that for small motors not in the tables, the locked rotor current should be assumed to be six times the FLC.
Question 8 of 10
What is the specific requirement for a disconnect used for a torque motor?
According to 430.110(B), the disconnecting means for torque motors shall have a rating of 115% of the nameplate full-load amperes (FLA).
Question 9 of 10
Under what condition can the controller's disconnect also serve as the disconnect for the motor?
Per 430.102(B), if the controller's disconnect is within sight of the motor, it can also serve as the disconnect for the motor.
Question 10 of 10
If control circuit conductors are not tapped from the controller disconnect and are supplied by a Class 1 control circuit, what is required?
The article states that if not tapped from the controller disconnect, a separate disconnect must be installed adjacent to the controller disconnect.
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