Deleting 310.15(B)(7)

[George Stolz]

(7) For service and feeder conductors of 120/240-volt, single-phase, individual dwelling unit one-family, two-family, and multifamily service ratings from 100 through 400 amperes, an adjustment factor of 0.83 of the service ampere rating shall be permitted to be used to determine the size of the ungrounded conductors. The grounded conductor shall be permitted to be smaller than the ungrounded conductors, provided that the requirements of 215.2, 220.61, and 230.42 are met.
Informational No. 1: The conductor ampacity may require other correction or adjustment factors applicable to the
conductor installation.
Informational No. 2: See example DXXX in Annex D.

1.) Comment on Proposal No.: 6-49a
2.) Recommendation: Reject this proposal.
3.) Substantiation: I salute the panel for taking the first step in kicking their harrowing Residential Feeder Table Addiction (commonly referred to as "RFTA"), and deleting the Table. It's a good first step, much like throwing the needle and spoon into the garbage after kicking heroin. Take several deep breaths, throw 310.15(B)(7) into the trash can, and set it on the curb. It is important for the panel to understand that residential load diversity is not similar to an ambient temperature, it is not similar to bundling, it is a direct result of an unexpected decrease in load.
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Delete section 310.15(B)(7) and Table 310.15(B)(7).

1.) Comment on Proposal No.: 6-51
2.) Recommendation: Reconsider and accept this proposal.
3.) Substantiation: The panel's action in proposal 6-49a still has a fundamental problem. Conductors connected to circuit breakers are required to be sized to 125% of the continuous load in order for the conductor to draw heat away from the breaker as a heat sink. By the panel's action, undersized conductors are still allowed to be connected to overcurrent devices. By accepting this proposal and leaning on CMP-2 to accept a load diversity factor in lieu of 310.15(B)(7), this basic problem is averted while meeting the intentions of CMP-6. It is the right way to put this issue to bed, forever.
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220.58 (new) Load Diversity ? Dwelling Unit(s). It shall be permissible to apply a demand factor of 88% to the total calculated load, after applying demand factors allowed in other portions of this Article, where the feeder or service conductors supply all of the loads associated with an individual dwelling unit. This demand factor shall not be applied to conductors serving more than one dwelling unit.

Panel Statement: The submitter has not provided any substantiation to reduce the calculated load to 88% of its Article 220 value.

1.) Comment on Proposal No.: 2-247
2.) Recommendation: Accept this proposal.
3.) Substantiation: I hate to be a snitch, but CMP-6 has been effectively reducing the calculated load to 88% (or to hear them talk, 83%) for over thirty years. The substantiation for 310.15(B)(7)'s original acceptance into the NEC is the same substantiation for this proposal. The requirement should be moved to new 220.58 to eliminate ongoing problems with 310.15(B)(7), contingent upon it's deletion.