Free TN-LLE HVAC and Air-Conditioning Circuits Questions and Answers

Question 1

A hermetic refrigerant motor-compressor has a rated-load current (RLC) of 20A. What is the minimum ampacity for the branch-circuit conductors supplying this motor-compressor?

Accepted Answer

25A

Answer

20A

Answer

30A

Answer

23A

Question 2

According to NEC Article 440, a disconnecting means for an air-conditioning unit must be located within sight from the unit. What is the maximum distance to be considered "within sight"?

Accepted Answer

50 feet

Answer

25 feet

Answer

75 feet

Answer

100 feet

Question 3

An A/C unit's nameplate lists the rated-load current as 24A and specifies a "Maximum Fuse Size" of 40A. What is the maximum size inverse-time circuit breaker that can be used for branch-circuit protection?

Accepted Answer

40A

Answer

30A

Answer

45A

Answer

50A

Question 4

A 120-volt, cord-and-plug-connected room air conditioner is installed on a branch circuit that also supplies lighting outlets. What is the maximum permissible rated current of the air conditioner?

Accepted Answer

50% of the branch-circuit rating

Answer

80% of the branch-circuit rating

Answer

100% of the branch-circuit rating

Answer

125% of the branch-circuit rating

Question 5

Which of the following is NOT a required marking on an air-conditioning unit's nameplate according to NEC 440.4?

Accepted Answer

Recommended conductor size

Answer

Manufacturer's name

Answer

Rated-load current in amperes

Answer

Phase and Voltage

Question 6

An air-conditioning unit has a rated-load current of 18A and a locked-rotor current of 90A. What is the minimum ampere rating for the required disconnecting means?

Accepted Answer

30A

Answer

20A

Answer

25A

Answer

18A