Practice Test Geeks(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test
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Electrical Components and Wiring Flashcards

7 cards from real 313D practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Electrical Components and Wiring flashcards as text

  1. What is the purpose of a start capacitor in a single-phase AC compressor motor?

    Answer: Provide a phase shift to boost starting torque

    A start capacitor creates a phase shift in the start winding current, producing the torque needed to overcome inertia and start the motor.

  2. Which wire color is designated as the common conductor in a standard residential thermostat wiring scheme?

    Answer: Blue or Black (C)

    The C (common) wire, typically blue or black, completes the 24V control circuit by providing the return path to the transformer secondary.

  3. A residential air conditioning system uses a 240V/24V step-down transformer. If the primary side shows 240V but the secondary shows 0V, the MOST likely cause is:

    Answer: Open primary winding or blown fuse

    An open primary winding or a blown fuse on the primary side will prevent current flow and result in zero secondary voltage output.

  4. What is the standard voltage range for the low-voltage control circuit in residential HVAC equipment?

    Answer: 24V AC

    Residential HVAC control circuits operate at 24V AC, supplied by the system transformer, to power thermostats, relays, and contactors.

  5. A contactor coil measures infinite resistance with an ohmmeter. This indicates the coil is:

    Answer: Open and will not energize

    Infinite resistance on a coil indicates an open circuit, meaning no current can flow through the coil and the contactor will not pull in.

  6. When sizing wire for a residential condensing unit, which document provides the minimum circuit ampacity and maximum overcurrent protection?

    Answer: Unit installation manual and nameplate data

    The unit nameplate and installation manual list MCA (Minimum Circuit Ampacity) and MOCP (Maximum Overcurrent Protection), which must be used for wire and breaker sizing.

  7. A run capacitor rated 45+5 MFD is used with a condenser fan motor and compressor. What do the two capacitance values represent?

    Answer: Compressor and fan motor capacitance respectively

    In a dual-run capacitor, the larger value (45 MFD) serves the compressor and the smaller value (5 MFD) serves the condenser fan motor.

Electrical Components and Wiring Flashcards — 313D Study Cards with Answers