Bonding

DOE-HDBK-1092-98

4.4 BONDING

Caution shall be taken to ensure that the main bonding jumper and equipment bonding jumper are

sized and selected correctly. Bonding completes the grounding circuit so that it is continuous. If a

ground fault occurs, the fault current will flow and open the overcurrent protection devices. The

means of bonding shall provide the following to ensure the grounding system is intact:

1. Provide a permanent connection,

2. Provide a positive continuity at all times, and

3. Provide ampacity to conduct fault current.

See Figure 4-1 on the proper grounding of electrical systems.

Supply

Grounded (neutral) conductor

carrying fault current

Service

equipment

Phase

conductor

Overcurrent

This equipment grounding

Protective

conductor provides

Device

equipment grounding

This conductor

Subpanel

provides the

bonding of the

equipment

Equipment with

ground fault

This grounding electrode

provides circuit and

system grounding

NEC Section 250-51

Figure 4-1. Circuit and system grounding consists of earth grounding the electrical system at the supply

transformer and the line side of the service equipment. Equipment grounding and bonding is accomplished by

connecting all metal enclosures and raceways together with the grounding conductors.

4-3