IEC Grounding and Bonding 3

Question 1

What is the maximum resistance to ground allowed for a single ground rod electrode before a supplemental electrode is required per NEC 250.56?

Accepted Answer

25 ohms

Answer

NEC 250.56 requires a supplemental electrode if a single rod, pipe, or plate electrode has a resistance to ground exceeding 25 ohms.

Question 2

Which conductor is used to bond the structural steel of a building to the grounding electrode system?

Accepted Answer

Grounding electrode conductor

Answer

The grounding electrode conductor connects the grounding electrode system to the electrical system, including structural steel when used as an electrode.

Question 3

Per NEC 250.104(A), interior metal water piping must be bonded to which of the following?

Accepted Answer

The service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor, or the grounding electrodes

Answer

NEC 250.104(A) requires interior metal water piping to be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor, or one of the grounding electrodes.

Question 4

What type of grounding electrode is considered 'made' rather than 'existing' per NEC 250.52?

Accepted Answer

Rod and pipe electrode

Answer

Rod and pipe electrodes are intentionally installed (made) electrodes, whereas water pipes, building steel, and concrete-encased electrodes are naturally occurring or part of the structure.

Question 5

What is the minimum length of a ground rod required by NEC 250.52(A)(5)?

Accepted Answer

8 feet

Answer

NEC 250.52(A)(5) requires ground rods to be at least 8 feet in length when installed in the earth.

IEC - Independent Electrical Contractors Practice Test

IEC - Independent Electrical Contractors Practice Test

IEC Grounding and Bonding 3