Licensed Electrical Contractor Licensed Electrical Contractor Grounding and Bonding Questions and Answers 3

Question 1

What type of grounding electrode is formed by at least 20 feet of steel reinforcing bars (rebar) tied together within a concrete foundation?

Accepted Answer

Concrete-encased electrode

Answer

A concrete-encased electrode (Ufer ground) uses rebar or bare copper embedded at least 20 feet in a building foundation.

Question 2

Per NEC 250.64(E), when multiple service disconnects are located in separate enclosures, how may the grounding electrode conductor be run?

Accepted Answer

It may be tapped using listed connectors at each enclosure

Answer

NEC 250.64(E) permits tapping the grounding electrode conductor at each service disconnect using listed connectors.

Question 3

What is the minimum burial depth required for a driven ground rod to be effective per NEC 250.53(G)?

Accepted Answer

8 feet

Answer

NEC 250.53(G) requires driven rod electrodes to have at least 8 feet of contact with the soil.

Question 4

Which of the following is an acceptable method for bonding around a water meter to maintain grounding continuity?

Accepted Answer

Installing a bonding jumper across the meter

Answer

A bonding jumper must be installed around the water meter to ensure continuous grounding because meters can be removed for service.

Question 5

According to NEC 250.122, how is the minimum size of an equipment grounding conductor determined for a branch circuit?

Accepted Answer

By the rating of the overcurrent device protecting the circuit

Answer

NEC Table 250.122 sizes equipment grounding conductors based on the rating of the overcurrent device ahead of the circuit.

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