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Grounding, Bonding & Overcurrent Protection 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 Grounding, Bonding & Overcurrent Protection flashcards as text

  1. Per NEC 250.119, equipment grounding conductors must be identified by which of the following?

    Answer: Green insulation, green with yellow stripes, or bare conductor

    NEC 250.119 requires EGCs to be identified by green insulation, green with yellow stripe insulation, or as a bare conductor to distinguish them from current-carrying conductors.

  2. Per NEC 250.53(A)(2), when is a supplemental grounding electrode required when a single rod, pipe, or plate electrode is used?

    Answer: When the single electrode has a resistance to ground exceeding 25 ohms

    NEC 250.53(A)(2) requires a supplemental electrode when a single rod, pipe, or plate electrode has a resistance to ground exceeding 25 ohms.

  3. Per NEC 250.64(B), a grounding electrode conductor of what size or smaller must be protected from physical damage by installation in a raceway or armor?

    Answer: 6 AWG or smaller

    NEC 250.64(B) requires that a 6 AWG or smaller copper GEC exposed to physical damage be protected by installing it in rigid metal conduit, IMC, PVC conduit, EMT, or cable armor.

  4. Per NEC 250.70, connections of grounding electrode conductors to grounding electrodes must be made using:

    Answer: Listed lugs, listed pressure connectors, listed clamps, or other listed means approved for the purpose

    NEC 250.70 requires that connections of GECs to grounding electrodes use listed lugs, listed pressure connectors, listed clamps, or other listed means approved for the material and electrode type.

  5. Per NEC 240.4(D)(3), what is the maximum overcurrent protection permitted for a 10 AWG copper branch-circuit conductor?

    Answer: 30A

    NEC 240.4(D)(3) limits overcurrent protection for 10 AWG copper conductors to a maximum of 30A in branch circuits.

  6. Which grounding electrode has the highest priority in the grounding electrode system hierarchy per NEC 250.50?

    Answer: Metal underground water pipe with 10+ feet in contact with soil

    NEC 250.52(A)(1) lists the metal underground water pipe as the first electrode in the hierarchy, and NEC 250.50 requires it to be used if present, supplemented by additional electrodes.

  7. When a grounding electrode conductor is run inside a ferrous metal raceway, what bonding requirement applies per NEC 250.64(E)?

    Answer: The raceway must be bonded to the GEC at both ends to prevent inductive choke effect

    NEC 250.64(E) requires ferrous metal raceways enclosing GECs to be bonded to the GEC at both ends to prevent inductive heating and voltage drop caused by the raceway acting as a choke.