Practice Test Geeks(CME) Certified Master Electrician Practice Test
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System Design and Installation Flashcards

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

Read the first 7 System Design and Installation flashcards as text

  1. In designing a motor control center (MCC) for an industrial plant, what is the minimum short-circuit current rating (SCCR) that must be marked on the MCC assembly per NEC 409.110?

    Answer: 5,000A minimum unless labeled for specific ampere rating

    NEC 409.110(4) requires industrial control panels to be marked with their SCCR, with a minimum of 5,000A unless the panel is marked for a specific higher rating.

  2. When designing a branch circuit for a household cooking range rated at 12 kW, what is the calculated demand load per NEC Table 220.55?

    Answer: 8 kW

    NEC Table 220.55 Column C specifies 8 kW demand load for a single household cooking range rated 12 kW.

  3. A 480V feeder supplies multiple HVAC units. Under NEC 430.24, how must the feeder conductor ampacity be calculated for a group of motors?

    Answer: 125% of the largest motor FLA plus 100% of all remaining motor FLAs

    NEC 430.24 requires feeder conductors to have ampacity of 125% of the highest rated motor FLA plus the sum of all other motor FLAs in the group.

  4. When designing a raceway system through a fire-rated wall, what is required at each penetration per NEC 300.21?

    Answer: The opening must be fire-stopped to maintain the fire rating

    NEC 300.21 requires that penetrations through fire-resistant-rated walls, floors, and ceilings be firestopped using approved methods to maintain the fire resistance rating.

  5. In a Class I, Division 1 hazardous location, which wiring method is specifically permitted per NEC 501.10(A)?

    Answer: Threaded rigid metal conduit (RMC) or threaded steel intermediate metal conduit (IMC)

    NEC 501.10(A)(1) requires threaded rigid metal conduit or threaded steel IMC as the primary wiring method for Class I, Division 1 locations.

  6. What is the maximum length of a flexible connection permitted between rigid conduit and a motor to allow for vibration isolation per NEC 430.245(B)?

    Answer: 36 inches

    NEC 430.245(B) permits flexible conduit connections up to 36 inches in length at motor terminals to allow for vibration, misalignment, or interchangeability.

  7. When a master electrician designs a feedthrough neutral in a 120/240V system, at what point is the neutral NOT permitted to be reduced in size below the phase conductors?

    Answer: When the neutral carries harmonic currents from nonlinear loads

    NEC 220.61(C) prohibits neutral reduction when the major portion of the load consists of nonlinear loads, such as electronic equipment that generates harmonic currents, because the neutral may carry more current than the phase conductors.