Practice Test Geeks(PC) Professional Electrical Contractor Practice Test
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Grounding and Bonding Flashcards

7 cards from real PC 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. What is the maximum resistance to ground allowed for a driven ground rod per NEC 250.56 before a second electrode is required?

    Answer: 25 ohms

    NEC 250.56 requires a supplemental electrode if a single driven rod has a resistance to ground exceeding 25 ohms.

  2. Intersystem bonding terminations (IBTs) are required to be accessible and located within how many feet of the service entrance or the grounding electrode conductor?

    Answer: No distance limit is specified

    NEC 250.94 requires IBTs to be accessible but does not specify a maximum distance from the service; placement is determined by practicality.

  3. Which conductor connects the grounded service conductor (neutral) to the grounding electrode system at the service equipment?

    Answer: Main bonding jumper (MBJ)

    The main bonding jumper connects the grounded (neutral) conductor to the equipment grounding conductor at the service equipment per NEC 250.28.

  4. When bonding metal water piping in a building, the bonding jumper must be connected to the piping at a point within how many feet of where the water service enters the building?

    Answer: 5 feet

    NEC 250.68(C)(1) requires the bonding connection to interior metal water piping within 5 feet of where the pipe enters the building.

  5. A grounding electrode conductor for a residential 200A service must be at least what size if using copper?

    Answer: #4 AWG

    NEC Table 250.66 requires a minimum #4 AWG copper GEC for service conductors of 2/0 AWG or smaller copper (typical for 200A residential).

  6. What type of electrode is formed by 20 or more feet of bare copper conductor buried at least 30 inches below grade encircling a building?

    Answer: Ground ring

    NEC 250.52(A)(4) defines a ground ring as bare copper conductor, at least #2 AWG, buried at least 30 inches deep and encircling the building.

  7. Which of the following is NOT permitted to be used as a grounding electrode per NEC 250.52?

    Answer: Underground gas piping system

    NEC 250.52(B) explicitly prohibits underground gas piping systems from being used as a grounding electrode.