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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.

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  1. A master electrician is designing a data center with a 1200A service. Per NEC 230.71, what is the maximum number of disconnects permitted for a service?

    Answer: 6

    NEC 230.71(A) limits the number of service disconnecting means to a maximum of six in a single enclosure or group of enclosures.

  2. When installing a 277V fluorescent lighting system in a wet location, which wiring method is prohibited per NEC 410.10(D)?

    Answer: Nonmetallic sheathed cable

    NMC (nonmetallic sheathed cable) is not listed for use in wet locations and is prohibited for wet location lighting installations.

  3. In an arc flash hazard analysis, what standard provides the methodology for calculating incident energy and arc flash boundaries?

    Answer: IEEE 1584

    IEEE 1584 provides the empirical equations and methodology for calculating arc flash incident energy and arc flash protection boundaries.

  4. What is the minimum burial depth for a 120/240V, single-phase residential service lateral using direct burial cable (UF) per NEC Table 300.5?

    Answer: 24 inches

    NEC Table 300.5 requires direct burial cable at residential voltages not exceeding 240V to be buried at least 24 inches deep.

  5. When designing an outdoor substation for an industrial facility, what is the minimum working clearance required in front of 480V switchgear (Condition 2) per NEC Table 110.26(A)(1)?

    Answer: 3.5 feet

    NEC Table 110.26(A)(1) requires 3.5 feet (42 inches) of working clearance for Condition 2 at 151–600V.

  6. A master electrician is designing a multi-building campus distribution system. Which grounding method is required when a feeder extends to a separate building with its own disconnect per NEC 250.32?

    Answer: A grounding electrode system must be installed at the separate building

    NEC 250.32(A) requires a grounding electrode system to be connected to the disconnecting means at a separate structure supplied by a feeder or branch circuit.

  7. When installing an energy storage system (ESS) in a commercial building, which NEC article provides the specific installation requirements?

    Answer: Article 706

    NEC Article 706 covers stationary standby and energy storage systems including battery systems, flywheels, and capacitors used for energy storage.