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Grounding versus Bonding

PART I.

Sections

250.2 Definitions Continued

Ground (Earth) [100]. Earth or a conductive body that is connected to earth. Figure 250–6

Grounded [100]. Connected to earth.

Ground Fault [100]. An unintentional connection between an ungrounded conductor and metal parts of enclosures, raceways, or equipment. Figure 250–7

Ground-Fault Current Path [250.2]. An electrically conductive path from a ground fault to the electrical supply source.

Author’s Comment: The fault-current path of a ground fault is not to the earth! It’s to the electrical supply source, typically the X0 terminal of a transformer.

FPN: The ground-fault current path could be metal raceways, cable sheaths, electrical equipment, or other electrically conductive materials, such as metallic water or gas piping, steel-framing members, metal ducting, reinforcing steel, or the shields of communications cables. Figure 250–8

Author’s Comment: The difference between an “effective ground-fault current path” and “ fault-current path” is that the effective ground-fault current path is “intentionally” constructed to provide the low-impedance fault-current path to the electrical supply source for the purpose of clearing the ground fault. A ground-fault current path is simply all of the available conductive paths over which fault current flows on its return to the electrical supply source during a ground fault.
Grounded (Earthed) [100]. Connected to earth.

Grounded Neutral Conductor [100]. The conductor that terminates to the terminal that is intentionally grounded to the earth. Figure 250–9

Grounding (Earthing) Conductor [100]. The conductor that connects equipment to the earth via a grounding electrode.

Author’s Comment: An example would be the conductor used to connect equipment to a supplementary grounding electrode [250.56]. Figure 250–10


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