Amend 310.15(B)(6) (Resi Ratings)

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George Stolz

George Stolz

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1.) NEC Section/Paragraph: 310.15(B)(6) text
2.) Proposal Recommends: [revised text]
3.) Proposal: Amend text to read:

 Conductors shall be permitted to be connected to equipment rated according to Table 310.15(B)(6) under the following conditions:
(a) The supply is a single phase, 120/240 Volt, 3 wire system.
(b) The conductors are installed for one-family, two family, and multifamily dwellings
(c) The conductors are service laterals, service entrance conductors, and/or feeders that serve only one individual dwelling unit.
(d) These conductors shall serve as the main power feeder to each dwelling unit.
(e) These conductors shall serve lighting and appliance branch-circuit panelboards.

For the purposes of this section, the main power feeder shall be the feeder(s) between the main disconnect and the panelboard(s). The grounded conductor shall be permitted to be smaller than the ungrounded conductors, provided the requirements of 215.2, 220.61, 230.42 are met.

4.) Substantiation: As the text currently stands, the first sentence of this section is very difficult to read, containing 56 words seperated by no less than nine commas. This section is packed with various requirements. It would be much clearer to understand and more readily and accurately applied in a list format. It is very easy to misapply this section as it currently stands.

In addition, given the general hierarchy of overcurrent protection and conductor installation, the sentence that allows feeders to not be larger than the service conductors is unnecessary. If such an improbable installation were to occur, then it's reasonable to require the conductor ampacities given in subsequent tables to apply.

So how's about that? :D

[ July 21, 2005, 07:52 PM: Message edited by: georgestolz ]
 
Re: Amend 310.15(B)(6) (Resi Ratings)

George, listed below are all my objections to your proposal </font>
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<font size="2" face="Verdana, Helvetica, sans-serif">:D
 
Re: Amend 310.15(B)(6) (Resi Ratings)

Nice text George. This section has been changed several times over the last few cycles, yours is a good proposal.
 
Looks as though this one has some hope, but I need to revise the text I originally submitted:

6-65 Log #1410 NEC-P06 Action: Reject
(310.15(B)(6))
Panel Meeting Action: Reject

Panel Statement: The proposed text does not require compliance with all the list items and omits some existing requirements (?and are installed in raceway or cable with or without an equipment grounding conductor?). The panel appreciates the submitter?s efforts to improve the readability and clarity of the Section but any revised text must require that the installation comply all of the existing requirements.
Click to expand...

It appears I need to edit the first sentence to read "all the following conditions". I also need to add: "(f) The conductors are installed in a raceway or cable, with or without an equipment grounding conductor."

I don't understand what they are trying to prohibit by these statements, however. All installations under the sun are either with or without an equipment grounding conductor, so it seems like a waste of ink to me. :?:

Services and feeders are required to comply with Chapter 3, so what does the "in a raceway or cable" statement add? :?:
 
I think your proposal is right on. Seem to remember years ago it was more clear than what is presently written. Too bad some of the English majors have to muck up clear sentences. Of course the legalese wannabes do a fair job of damage also.
 
I was mostly surprised that they didn't just 'accept in principle' and add the omitted text on their own. I thought this proposal had a high probability of success for it's clarity.

Hopefully, they accept it with the changes. I don't mind adding some (of what I consider to be) nonsense if the overall section is improved.
 
I think your intent is that all of (a) - (e) must apply. However, (c) and (d) are mutually exclusive for service conductors (its either a service wire or a feeder, can't be both).

The "raceway or cable, with or without ground" gets to another issue. Based on normal wiring rules, the only thing I see this would exclude would be direct buried individual wires. I don't know why you'd want to eliminate those, as it seems they don't have high ambients and are not a fire hazard. Is it OK to burn up a USE cable but not individual USE wires?

As one who would like to apply this to all feeders, I'd word it differently. But to keep your meaning, I'd suggest modifying part (d) to "If a feeder, it shall be the main power feeder to each dwelling unit."
 
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