Practice Questions: Grounding & Bonding
Real questions from our bank, all referenced to NEC 2026. Tap “Show explanation” after you answer.
Per NEC 250.52(A)(2), a metal frame of a building or structure shall be used as a grounding electrode when which condition is met?
- AThe building is over three stories tall
- BThe metal frame is effectively grounded
- CThe building has a lightning protection system
- DThe metal frame supports electrical equipment
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NEC 250.52(A)(2) requires the metal frame of a building to be used as a grounding electrode when it is effectively grounded.
Per NEC 250.53(D)(2), a ground rod electrode that does not have a resistance to ground of 25 ohms or less shall be supplemented by one additional electrode. What is the minimum spacing between the two electrodes?
- A3 feet
- B6 feet
- C8 feet
- D10 feet
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NEC 250.53(D)(2) requires supplemental ground rods to be separated by at least 6 feet from each other.
Per NEC 250.119, equipment grounding conductors may be identified by which of the following methods?
- AContinuous green color or green with yellow stripes
- BWhite or gray insulation
- CBlue insulation
- DRed insulation
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NEC 250.119 requires EGCs to be identified by continuous green insulation, green with one or more yellow stripes, or bare copper.
Per NEC 250.64(A), a grounding electrode conductor made of aluminum or copper-clad aluminum shall not be installed in which location?
- AInside rigid metal conduit
- BIn direct contact with masonry or the earth, or where subject to corrosive conditions
- CIn PVC conduit
- DInside EMT
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NEC 250.64(A) prohibits aluminum or copper-clad aluminum grounding electrode conductors from being installed where in direct contact with masonry, the earth, or subject to corrosive conditions.
Per NEC Table 250.122, what is the minimum size copper equipment grounding conductor required for a branch circuit protected by a 60-ampere overcurrent device?
- A12 AWG
- B10 AWG
- C8 AWG
- D6 AWG
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Per NEC Table 250.122, a branch circuit protected by a 60 A overcurrent device requires a minimum 10 AWG copper equipment grounding conductor. The EGC is sized based on the rating of the overcurrent device, not the size of the phase conductors.
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