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Grounding versus Bonding

PART VII.

Sections

250.130 Equipment Grounding (Bonding) Conductor Connections.

(A) For Grounded Systems. The service disconnecting means supplied by a grounded utility system must have the grounded neutral service conductor bonded to the service-disconnect enclosure in accordance with 250.24(C). The grounded neutral service conductor must also be bonded to the grounding (earthing) electrodes [250.24(A)] and the equipment grounding (bonding) conductors.

(B) For Ungrounded Systems. The service disconnecting means supplied by an ungrounded utility system must have the service-disconnect enclosure grounded to a grounding electrode in accordance with 250.24(E). The equipment grounding (bonding) conductors must also be bonded to the grounding (earthing) electrodes [250.130(B)].

(C) Nongrounding Receptacle Replacement or Branch-Circuit Extensions. Where a nongrounding receptacle is replaced with a grounding-type receptacle, or when a branch-circuit extension is made from an outlet box that doesn’t contain an equipment grounding (bonding) conductor, the grounding contacts of the receptacle must be grounded (bonded) to one of the following (effective ground-fault current path): Figure 250–176

(1) Grounding electrode system [250.50] (which is bonded to the grounded neutral service conductor).

(2) Grounding electrode conductor (which is bonded to the grounded neutral service conductor).

(3) Panelboard equipment grounding terminal.

(4) Grounded neutral service conductor.

Author’s Comment: A branch-circuit extension is not permitted to be made from an outlet box that doesn’t have an equipment grounding (bonding) conductor, unless an equipment grounding (bonding) conductor for the circuit extension is run as specified in 250.130(C)(1) through (4). Figure 250–177

FPN: A grounding-type receptacle can replace a nongrounding type receptacle, without having the grounding terminal grounded (bonded) to an effective ground-fault current path, if the receptacle is GFCI protected and marked in accordance with 406.3(D)(3). Figure 250–178

Author’s Comment: But this rule does not apply to new grounding-type receptacles placed on a branch-circuit extension from an existing outlet box that does not have an equipment grounding (bonding) conductor.


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