Significant Proposals for 2005 NEC Part V

As Reviewed by Mike Holt

The following text is a quick summary of the proposed changes for the 2005 NEC. This document is a work in progress and many will be changed by the Code panel over the next few months. Some of these you might find important to your work and you might want to follow their progress with me. Therefore, each week I will email you a few of these changes.

Each proposed change has a Report on Proposal (ROP) number, like 1-25. This number reflects the Proposal Number and all action on this proposal can be viewed in the following PDF document NEC Part2.

As always, I am looking to improve our products, so if you feel you have anything to contribute, please let me know at Mike@MikeHolt.com.

Article 250 Grounding and Bonding

5-37
Article 250 Grounding and Bonding
Change the title of Article 250 from "Grounding" to "Grounding and Bonding" so that it is consistent with the scope of Article 250.

Author's Comment: The scope of this article states, "This article covers general requirements for grounding and bonding of electrical installations.

5-48
250.2 Definition
Effective Ground-Fault Current Path. Additional text should help the Code user understand that the purpose of the effective ground-fault path is to help clear a ground-fault by facilitating the operation of the overcurrent device.

5-49
250.2 Definitions
Ground Fault. Revise the text to indicate that a ground fault can include an unintended connection of the grounded (neutral) conductor to the equipment grounding (bonding) conductor.

Author's Comment: The ground-fault connection of the grounded (neutral) conductor to the equipment grounding (bonding) on the load side of service equipment and separately derived systems results in objectionable current flow on the grounding and bonding conductors in violation of 250.6 and 250.142(B).

Caution: A GFCI and AFCI protection device will tip when a ground fault of the grounded (neutral) conductor to the equipment grounding (bonding) conductor occurs on the load side of the protective device.

5-52
250.4 General Requirements for Grounding and Bonding.
(A) Grounded Systems.
(5) Effective Ground-Fault Current Path. Clarify that swift operation of an overcurrent protection device in the presence of a ground-fault is dependent upon the existence of a low-impedance effective ground-fault current path from the point of the fault to the power supply.

5-52
250.4 General Requirements for Grounding and Bonding.
(A) Grounded Systems.
(5) Effective Ground-Fault Current Path. The last sentence was revised to make it clear that the earth is not to be used as the low-impedance effective ground-fault current path necessary to facilitate the opening of the circuit protection device from a ground fault.

5-57
250.8 Connection of Grounding and Bonding Equipment
Revised text clarifies that terminals for grounding conductors or bonding jumpers must be attached to enclosures in a suitable method to ensure an effective ground-fault path.

Author's Comment: The rule does not prohibit dry wall screws or wood screws to be used for this purpose!


5-67
250.24 Grounding Service-Supplied Alternating- Current Systems.
(A) System Grounding Connections.
(4) Main Bonding Jumper as Wire or Busbar. The term "neutral conductor" was replaced with "grounded conductor."

Author's Comment: Neutral is a term that has been misused for generations, but the NEC should not be using it incorrectly.

5-65, 5-69
250.24 Grounding Service-Supplied Alternating- Current Systems.
(B) Main Bonding Jumper. The requirement for the main bonding jumper was relocated to 250.24(B) from 250.28.

5-74, 5-80, 5-84
250.28 Main Bonding Jumper and System Bonding Jumper.
To avoid confusion when dealing with bonding jumpers, the requirement for the system bonding jumper (new term) was added to this section.

Author's Comment: A system bonding jumper is the conductor that is installed between the grounded (neutral) terminal of a separately derived system and the metal case [Article 100].

5-102
250.30 Separately Derived Systems
(A) System Grounding Connections
(2) Equipment Bonding Jumper Size. Text revised to clarify the sizing requirement for parallel secondary equipment bonding jumpers.

5-78
250.30 Separately Derived Systems
(A) System Grounding Connections
(4) Grounding Electrode Conductor, Multiple Separately Derived Systems. Text revised requires the "common" grounding electrode conductor, for multiple separately derived systems, to be sized no smaller than 3/0 AWG.

5-93
250.30 Separately Derived Systems
(A) System Grounding Connections
(4) Grounding Electrode Conductor, Multiple Separately Derived Systems
(c) Connections. Rules for terminating the grounding electrode tap conductor to the common grounding electrode conductor changed to clarify that listed pressure connectors (including set-screw type) are also permitted.


5-109
250.32 Buildings or Structures Supplied by Feeder(s) or Branch Circuit(s)
Revised text clarifies that a feeder or branch circuit to a separate building or structure is not required to be supplied "from a common service."

Author's Comment: Good, nobody knew what a "common service" was anyway.

5-109
250.32 Buildings or Structures Supplied by Feeder(s) or Branch Circuit(s)
(A) Grounding Electrode. New sentence added to the exception to clarify that a grounding electrode is not required at a remote building or structure supplied by a multiwire branch circuit.

5-111
250.34 Portable and Vehicle-Mounted Generators.
(A) Portable Generators. Text clarifies when the frame of a portable generator is not required to be grounded to a grounding electrode.

5-111
250.34 Portable and Vehicle-Mounted Generators.
(B) Vehicle-Mounted Generators. Text clarifies when the frame of a vehicle-mounted generator is not required to be grounded to a grounding electrode.

5-129

250.52 Grounding Electrodes
(A) Electrodes Permitted for Grounding
(5) Rod and Pipe Electrodes. Listed galvanized rods of the 1/2 in. diameter are now permitted.

Author's Comment: Unlisted galvanized rods of the 5/8 in. diameter are still permitted.

5-134
250.52 Grounding Electrodes
(A) Electrodes Permitted for Grounding
(7) Other Local Metal Underground Systems or Structures. Clarify that a supplemental electrode is not required for an underground metal well casings.

5-135

250.52 Grounding Electrodes
(B) Electrodes Not Permitted for Grounding
(1) Metal underground gas piping system. New FPN added to remind the Code user that gas piping that is likely to become energized must be "bonded" in accordance with the 250.104(B).

Author's Comment: The equipment grounding (bonding) conductor for the circuit that is likely to energize the gas piping can be used as the bonding means [250.104(B)]. So effectively, this means that no action is actually required by the electrical installer!

5-140
250.54 Supplementary Grounding Electrodes.
Section revised to help the Code user understand that an equipment grounding (bonding) conductor is an intentionally constructed to assist in clearing ground faults, and that the earth is not and never should be used for this purpose.

Author's Comment: Suitable equipment grounding (bonding) conductors are identified in 250.118 and they include a copper or aluminum conductor, RMC, IMC, EMT, as well as many others.

5-154
250.64 Grounding Electrode Conductor Installation
(B) Securing and Protection Against Physical Damage. New paragraph requires a "direct burial grounding electrode conductors" to have a minimum 12 in. of cover.

5-158
250.64 Grounding Electrode Conductor Installation
(C) Continuous.
(3) Busbars. New text permits the termination of grounding electrode conductors and bonding jumpers to a copper busbar as an alternative method of splices conductors for grounding electrodes.

5-161
250.64 Grounding Electrode Conductor Installation
(D) Grounding Electrode Conductor Taps. Text revised to clarify how to size the "common" grounding electrode conductor for grounding electrode taps.

5-162
250.64 Grounding Electrode Conductor Installation
(E) Enclosures for Grounding Electrode Conductors. The revisions are to clarify when the grounding electrode conductor is required to be bonded to the metal raceway or enclosure at both ends.

Author's Comment: "Nonferrous" metal raceways such as aluminum rigid conduit enclosing grounding electrode conductors are not required to meet the bonding provisions of this section.

5-162
250.64 Grounding Electrode Conductor Installation
(E) Enclosures for Grounding Electrode Conductors. Additional text clarifies how to size the bonding jumper for the grounding electrode conductor raceway.

5-176
250.68 Grounding Electrode Conductor and Bonding Jumper Connection to Grounding Electrodes.
(A) Accessibility. New exception explains when the grounding electrode conductor is permitted to be inaccessible when terminating to fireproofed structural metal
.


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