Grounding and Bonding 1

DEFINITIONS

100

This NEC Article 100 term simply means “the earth.”

What is Ground?

Code Reference: NEC Article 100

200

This conductor is intentionally grounded and normally carries return current.

What is the Grounded Conductor?

Code Reference: NEC Article 100

300

This conductor is part of the effective ground-fault current path but normally carries no current.

What is the Equipment Grounding Conductor (EGC)?

Code Reference: NEC Article 100

400

This conductor connects the service equipment to the grounding electrode system.

What is the Grounding Electrode Conductor (GEC)?

Code Reference: NEC Article 100

500

This term describes a path intentionally designed with low impedance to carry fault current back to the source and operate the OCPD

What is an Effective Ground-Fault Current Path?

Code Reference: NEC Article 100

ELECTRODES

100

The NEC recognizes this many grounding electrode types.

What is 8?

Code Reference: NEC 250.52(A)

200

This electrode must have at least 10 feet of direct contact with earth.

What is a Metal Underground Water Pipe?

Code Reference: NEC 250.52(A)(1)

300

This electrode is commonly known as a Ufer Ground.

What is a Concrete-Encased Electrode?

Code Reference: NEC 250.52(A)(3)

400

This electrode requires at least #2 AWG bare copper encircling the structure.

What is a Ground Ring?

Code Reference: NEC 250.52(A)(4)

500

A single rod electrode can avoid a supplemental electrode only if resistance to earth is proven to be less than or equal to this value.

What is 25 ohms?

Code Reference: NEC 250.53(A)(2)

SIZING

100

This NEC table is used to size grounding electrode conductors.

What is Table 250.66?

Code Reference: NEC Table 250.66

200

A GEC connected only to rod or pipe electrodes is not required to be larger than this copper size.

What is #6 AWG Copper?

Code Reference: NEC 250.66(A)

300

A GEC connected only to a concrete-encased electrode is not required to be larger than this copper size.

What is #4 AWG Copper?

Code Reference: NEC 250.66(B)

400

This NEC chapter and table provides conductor area values used for parallel service calculations.

What is Chapter 9, Table 8?

Code Reference: NEC Chapter 9 Table 8

500

Two sets of 3/0 copper conductors feeding a 400A service require this size copper grounding electrode conductor.

What is #2 AWG Copper?

Code Reference: NEC 250.66

GOTCHAS

100

This is specifically prohibited from being used as a grounding electrode.

What is Gas Piping?

Code Reference: NEC 250.52(B)(1)

200

This is commonly mistaken for “ground” but is actually a grounded conductor.

What is the Neutral?

Code Reference: NEC Article 100

300

If a hot wire faults to a metal enclosure and there is no EGC, this dangerous condition may occur.

What is the enclosure remains energized?

Code Reference: NEC 250.4(A)(5)

400

This is the minimum required spacing between two rod electrodes.

What is 6 feet?

Code Reference: NEC 250.53(A)(3)

500

True or False: 

Earth is considered an effective ground-fault current path.

What is False?

The earth has too much resistance to reliably clear faults.

Code Reference: NEC 250.4(A)(5)

PURPOSE

100

This protects against lightning, line surges, and accidental contact with higher voltage systems.

What is System Grounding?

Code Reference: NEC 250.4(A)(1)

200

This NEC section requires non-current carrying metal parts to be connected to earth to limit voltage.

What is 250.4(A)(2)?

Code Reference: NEC 250.4(A)(2)

300

This NEC section establishes the effective ground-fault current path.

What is 250.4(A)(3)?

Code Reference: NEC 250.4(A)(3)

400

This NEC section requires the fault return path to have low enough impedance to trip the breaker.

What is 250.4(A)(5)?

Code Reference: NEC 250.4(A)(5)

500

True or False: 

Grounding protects people by sending dangerous fault current into the earth.

What is False?

Grounding protects by creating a low-impedance return path back to the source.

Code Reference: NEC 250.4(A)(5)