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

Monitor refrigerant pressure only

Answer

Control indoor fan speed

Answer

Regulate compressor suction pressure

Question 2

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

Accepted Answer

Article 440

Answer

Article 210

Answer

Article 310

Answer

Article 250

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

Both hot conductors together

Answer

The neutral conductor

Answer

The ground wire

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

Maximum current the equipment can draw under any condition

Answer

Maximum fuse size allowed

Answer

Motor locked-rotor amperage

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

Install a higher-rated fuse

Answer

Replace the transformer

Answer

Restart the system immediately

Question 6

What is the typical voltage and frequency of the secondary side of an HVAC control transformer in the United States?

Accepted Answer

24V AC / 60Hz

Answer

12V AC / 60Hz

Answer

24V DC / 60Hz

Answer

48V AC / 60Hz

Question 7

What safety device is required by NEC to be within sight of, or lockable from, an HVAC unit's location?

Accepted Answer

Disconnect means

Answer

Ground fault circuit interrupter (GFCI)

Answer

Surge protector

Answer

Time-delay fuse