NATE Electrical and Controls 3

Question 1

What is the purpose of a defrost control board in a heat pump system?

Accepted Answer

Initiate and terminate the defrost cycle based on time and temperature

Answer

The defrost control board monitors time and outdoor coil temperature to initiate defrost and terminate it when the coil clears.

Question 2

Which NEC article governs the installation of HVAC equipment in commercial and residential applications?

Accepted Answer

Article 440

Answer

NEC Article 440 specifically covers air-conditioning and refrigerating equipment, including wiring, overcurrent protection, and disconnects.

Question 3

When measuring current with a clamp-on ammeter on a 240V single-phase circuit, which conductor should the clamp encircle?

Accepted Answer

Only one hot conductor

Answer

Clamping around a single hot conductor measures the full current in that leg of the circuit without cancellation.

Question 4

What does the term 'MCA' (Minimum Circuit Ampacity) indicate on an HVAC nameplate?

Accepted Answer

Minimum wire ampacity required for branch circuit conductors

Answer

MCA specifies the minimum ampacity that the branch circuit conductors must be rated to safely carry for the equipment.

Question 5

A technician finds a blown fuse in the control circuit. After replacing it, the fuse blows again immediately. What is the BEST next step?

Accepted Answer

Check for short circuits or grounded wiring in the control circuit

Answer

A repeatedly blown fuse indicates a short circuit or grounded wire in the control circuit that must be located and repaired.

NATE - North American Technician Excellence Practice Test