Thread: Grounds and Neutrals

Why would you want to install all the grounds and nuetrals togeather under the same lug through the entire panel?

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I posted the same question several weeks ago. The answer I get up here on the mountain is "weve always done it thataway."

LAZY!!!!

Anything in the NEC about this?

I found this in my archives .... I think I got it from Jim Katen Over on TIJ:

(Log #3287) 9- 113 - (384-21 (New) ): Accept
SUBMITTER: James T. Pauley, Square D Co.
RECOMMENDATION: Add a new 384-21 to read as follows:
384-21. Grounded Conductor Terminations. Each grounded conductor shall terminate within the
panelboard in an individual terminal that is not also used for another conductor. Exception: Grounded conductors of circuits with parallel conductors shall be permitted to terminate in a single terminal if the terminal is identified for connection of more than one conductor.
SUBSTANTIATION: This revision is needed to coordinate the installation requirements with a long standing product standard requirement. Clause 12.3.10 of UL 67 (Panelboards) states “An individual terminal shall be provided for the connection of each branch-circuit neutral conductor.” The requirement has been enforced in the past by a close review of the manufacturers markings and by NEC 110-3(b). However, since it is a rule that specifically effects how the installer can make connections, it is important that it be in the NEC. Even with the manufacturers markings, inspectors still indicate that they see a number of panelboards installed with two (or more) branch circuit neutrals under one terminal or they see an equipment grounding conductor and neutral under the same terminal.
There is very good rationale for the requirement in the product standards. Doubling up on the neutrals creates a significant problem when the circuit needs to be isolated. In order to isolate the circuit, the branch breaker is turned off and the neutral is disconnected by removing it from the terminal. If the terminal is shared with another circuit, the connection on the other (still energized) circuit will be loosened as well. This can wreak havoc, particularly if the neutral is part of a 120/240V multi-wire branch circuit. Also, the neutral assemblies are not evaluated with doubled-up neutrals in the terminals. The connection of a neutral and equipment grounding conductor creates a similar issue. One of the objectives of the particular arrangement of bonding jumpers, neutrals and equipment grounds is to allow circuit isolation while keeping the equipment grounding conductor still connected to the grounding electrode (see UL 896A - Reference standard for Service Equipment). When the neutral is disconnected, the objective is to still have the equipment ground solidly connected to the grounding electrode. If both the neutral and grounding conductor are under the same terminal, this cannot be accomplished. This addition to the NEC does not change any product or permitted wiring arrangement from what it is today. It will however, it will help installers to avoid wiring the panel in violation of 110- 3(b) and then have to contend with a red-tag from the inspector. The code language is proposed in a fashion to allow consistent enforcement of the provision by the AHJ. Although the UL wording is adequate for the product standard, it is important that the NEC language is as clear an unambiguous as possible. This is the reason for specifically noting that the terminal cannot be used for another conductor. Furthermore, the code requirement has been worded to make sure that both branch circuit and feeder neutrals are covered since it is not uncommon to have feeder breakers as well as branch breakers in the panelboard (the issue for the neutral is the same regardless of branch or feeder). Also, the term “grounded conductor” is used to be consistent with the code terminology and to recognize that not all grounded conductors are neutrals. An exception has been proposed to avoid any confusion relative to parallel circuit arrangements. In these instances, multiple neutrals could be in a single terminal if the terminal has been identified as acceptable for multiple conductors.
PANEL ACTION: Accept.
NUMBER OF PANEL MEMBERS ELIGIBLE TO VOTE: 11
VOTE ON PANEL ACTION:
AFFIRMATIVE: 11

2002 NEC 408.20 (the paragraph after the Exception)Grounding (ground) conductors shall not be connected to a terminal bar provided for grounded (neutral) conductors unless the bar is identified for the purpose and is located where interconnection between equipment grounding conductors and grounded circuit conductors is permitted or required by Article 250.

2002 NEC 408.21 Grounded Conductor Terminations.- - Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.- - - Exception: Grounded conductors of circuits with parallel conductors shall be permitted to terminate in a single terminal if the terminal is identified for connection of more than one conductor.

To add clarification to Richards post "Exception: Grounded conductors of circuits with parallel conductors shall be permitted to terminate in a single terminal if the terminal is identified for connection of more than one conductor." regarding the "parallel conductors" part.

From the NEC. (bold is mine - note that none of the exceptions apply)
- 310.4 Conductors in Parallel.
- - Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, neutral, or grounded circuit conductor, shall be permitted to be connected in parallel (electrically joined at both ends to form a single conductor).
- - - Exception No. 1: As permitted in 620.12(A)(1) .
- - - Exception No. 2: Conductors in sizes smaller than 1/0 AWG shall be permitted to be run in parallel to supply control power to indicating instruments, contactors, relays, solenoids, and similar control devices provided
- - - - (a) They are contained within the same raceway or cable,
- - - - (b) The ampacity of each individual conductor is sufficient to carry the entire load current shared by the parallel conductors, and
- - - - (c) The overcurrent protection is such that the ampacity of each individual conductor will not be exceeded if one or more of the parallel conductors become inadvertently disconnected.
- - - Exception No. 3: Conductors in sizes smaller than 1/0 AWG shall be permitted to be run in parallel for frequencies of 360 Hz and higher where conditions (a), (b), and (c) of Exception No. 2 are met.
- - - Exception No. 4: Under engineering supervision, grounded neutral conductors in sizes 2 AWG and larger shall be permitted to be run in parallel for existing installations.
- - - - FPN: Exception No. 4 can be used to alleviate overheating of neutral conductors in existing installations due to high content of triplen harmonic currents.
- - - The paralleled conductors in each phase, neutral, or grounded circuit conductor shall
- - - - (1) Be the same length
- - - - (2) Have the same conductor material
- - - - (3) Be the same size in circular mil area
- - - - (4) Have the same insulation type
- - - - (5) Be terminated in the same manner
- - - Where run in separate raceways or cables, the raceways or cables shall have the same physical characteristics. Conductors of one phase, neutral, or grounded circuit conductor shall not be required to have the same physical characteristics as those of another phase, neutral, or grounded circuit conductor to achieve balance.
- - - - FPN: Differences in inductive reactance and unequal division of current can be minimized by choice of materials, methods of construction, and orientation of conductors.
- - - Where equipment grounding conductors are used with conductors in parallel, they shall comply with the requirements of this section except that they shall be sized in accordance with 250.122.
- - - Conductors installed in parallel shall comply with the provisions of 310.15(B)(2)(a).