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

NEC 440.32 requires branch-circuit conductors supplying a single motor-compressor to have an ampacity of not less than 125% of the motor-compressor's rated-load current. Therefore, 20A multiplied by 1.25 equals 25A.

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

The term "In Sight From" is defined in NEC Article 100 as being visible and not more than 50 feet distant from the other. This rule ensures a technician can safely de-energize the unit while working on it.

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

NEC 440.4(B) states that equipment shall be installed in accordance with the manufacturer's recommendations included in the listing or labeling. If the nameplate specifies a maximum fuse or HACR circuit breaker size, that value must not be exceeded.

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

According to NEC 440.62(C), where a cord-and-plug-connected room air conditioner is connected to a branch circuit that also supplies lighting units or other appliances, the total rated current of the air conditioner shall not exceed 50% 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

NEC 440.4(A) lists required markings, including rated-load current, voltage, phase, and manufacturer's name. It does not mandate the recommended conductor size, as the electrician is responsible for calculating this based on the NEC.

TN LLE - Tennessee Limited Licensed Electrician Practice Test

TN LLE - Tennessee Limited Licensed Electrician Practice Test

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