FREE Licensed Electrical Contractor Grounding & Bonding Questions and Answers

Question 1

According to NEC Article 250, what is the primary purpose of bonding metallic parts of an electrical system?

Accepted Answer

To ensure all non-current-carrying metallic parts are at the same electrical potential, reducing potential differences during a ground fault.

Answer

To provide a low-impedance path for lightning strikes to dissipate into the earth.

Answer

To increase the overall resistance of the grounding electrode system for better fault clearing.

Answer

To prevent stray currents from entering the building's plumbing system.

Question 2

A licensed electrical contractor is installing a new main service panel in a commercial building. Which of the following components is NOT permitted to be used as a grounding electrode according to NEC 250.52(A)?

Accepted Answer

An aluminum electrode driven into the earth.

Answer

A metal underground water pipe in direct contact with the earth for 10 feet or more.

Answer

A metal well casing that is bonded to the service equipment enclosure.

Answer

The steel frame of a building, where effectively grounded.

Question 3

When installing a new separate building or structure supplied by a feeder or branch circuit, what is the minimum number of grounding electrodes typically required at the separate building or structure, assuming no existing suitable electrodes are present?

Accepted Answer

Two, regardless of resistance to ground.

Answer

One, if its resistance to ground is 25 ohms or less.

Answer

One, only if a ground ring is installed.

Answer

Three, if the building has multiple service entrances.

Question 4

A licensed electrical contractor is installing a new hot tub. What specific type of bonding is required for the metallic parts of the hot tub, such as the pump motor frame, heater, and metal ladders, according to NEC Article 680?

Accepted Answer

Equipotential bonding.

Answer

System bonding.

Answer

Service bonding.

Answer

Structural bonding.

Question 5

Which of the following statements best describes the function of the main bonding jumper in a typical electrical service installation?

Accepted Answer

It connects the grounded (neutral) conductor to the equipment grounding conductor and the service enclosure at the service disconnect.

Answer

It provides a path for fault current directly from the service entrance conductors to the earth electrode.

Answer

It is used to bond non-current-carrying metal parts of the service equipment to the utility transformer.

Answer

It connects the phase conductors to the grounding electrode conductor.

Question 6

When installing a grounding electrode conductor (GEC) from the service equipment to a driven ground rod, what is the minimum size required for the GEC if the service conductors are 3/0 AWG copper?

Accepted Answer

No. 6 AWG copper.

Answer

No. 4 AWG copper.

Answer

No. 2 AWG copper.

Answer

No. 8 AWG copper.