subpanel-residential

charlie b · Feb 17, 2006

Re: subpanel-residential

Originally posted by suemarkp: Can't you use 310.15(B)(6) with out the explicit permission stated in 215.2?

I should think so.

Originally posted by suemarkp: Seems redundant unless they were trying to expand or clarify the meaning or scope of 310.15(B)(6).

Perhaps it's just a cross-reference. The code does tell you, from time to time, that other sections of the code might pertain to the same topic. Perhaps they were trying to invite your attention to the fact that there is another option, other than 3101.6. I can't say. I don't know the author's intent.

All I have said is how I interpret the words, as written. But you may rest assured that I am not likely to be the one who makes the call on any project for which this question might arise. So you don't have to worry about my having a different opinion than your own. You have to sell your plan to the AHJ, not to me.

fastforward · Feb 18, 2006

Re: subpanel-residential

Originally posted by charlie b:
Fastforward: I think I see how we might be reading this differently. It has to do with the word "that." In my understanding of the English language, the word "that" refers back to the one thing that immediately preceded it in the list, not to the entire list, unless there is some clear separator that alters the meaning of "that."

I will restate the first sentence of 310.15(B)(6) in two versions. They have very different meanings.

Both versions start out with, "For individual dwelling units of one family, two family, and multi-family dwellings, conductors as listed in . . . " Now I'll show two versions:

VERSION 1:

Table 310.15(B)(6) shall be permitted as 120/240 volt, single phase . . .


. . . service entrance conductors that serve as the main power feeder to each dwelling unit. . .

and


. . . service lateral conductors that serve as the main power feeder to each dwelling unit. . .

and


. . . feeder conductors that serve as the main power feeder to each dwelling unit. . . .



Click to expand...

VERSION 2:

Table 310.15(B)(6) shall be permitted as 120/240 volt, single phase . . .


. . . service entrance conductors. . .

and


. . . service lateral conductors. . .

and


. . . feeder conductors that serve as the main power feeder to each dwelling unit. . . .



Click to expand...

Do you see the difference? I think you have been using Version 1. I have been using Version 2, and here is what Version 2 says to me:



If you have service entrance conductors that land on a panel in the house, then those conductors can be sized per the table. Furthermore, all feeders in the house (i.e., downstream of the panel) need not be larger than the service entrance conductors.



If you have service lateral conductors that land on a panel in the house, then those conductors can be sized per the table. Furthermore, all feeders in the house (i.e., downstream of the panel) need not be larger than the service lateral conductors.



If you have a feeder that starts at main disconnect that is remote from a panel in the house, but that lands on a panel in the house, then that feeder can be sized per the table. Furthermore, all feeders in the house (i.e., downstream of the panel) need not be larger than the service conductors that are upstream of the main disconnect. But you don't get to compare sizes of the feeders downstream of the panel with the feeder to the panel.

Charlie,
I was persuaded of version 2 the whole time.Perhaps I wasn't clear in my presentation of that.My bad.I think we can put this one to rest.Till we meet again.Thanks for all your input, it definetly was benifiting.

subpanel-residential

charlie b

Moderator

fastforward

Member