T310.15(B)(6) svc condctrs 2- & multifamily

[ToolHound]

Help please.

Table 310.15(B)(6) trouble.

From my guide/book breaking down the NEC comes the following quote:

"Table 310.15(B)(6) can't be used for service conductors for two-family or multifamily buildings."
END QUOTE

My question is...

What NEC text would support the just-quoted statement supposing a prohibition against use of the T310.15(B)(6) for svc conductors for two- or multifamily buidlings ?

I see no NEC text that clearly supports the just-quoted statement.

I am wondering what I am missing.

Thanks, Toolhound






pic from:
http://ecmweb.com/qampa/code-qa-2

 

[augie47]

Look at the first sentence in the actual Code of 310.15(B)(6)

"(a) For individual dwelling units of one-family, twofamily,
and multifamily dwellings, conductors, as listed......"

 

[david luchini]

310.15(B)(6) says "For INDIVIDUAL dwelling units of one-family, two-family and multifamily dwelling units..."

The table applies only to the feeder or service conductors to each individual dwelling unit, not to the conductors that feed multiple dwelling units. The illustration appears correct.

edit: Gus, as usual, is too fast

 

[ToolHound]

Look at the first sentence in the actual Code of 310.15(B)(6)

"(a) For individual dwelling units of one-family, twofamily,
and multifamily dwellings, conductors, as listed......"

David, Augie, OK, thanks. I see the point, i.e., the referenced Code sentence sez..."For individual dwelling units...." Okay, that removes some of the fog.

Next, related, in my 2008 NEC Handbook, for the same Code section/table (i.e., T310.15-B-6), in the shaded area commentary following the table, the writer states, quote:

"Provided a single set of 3-wire, single-phase, service-entrance conductors in raceway or cable supplies a one-framily, two-family, or multifamily dwelling, the reduced conductor size permitted by 310.15(B)(6) is applicable to the service-entrance conductors, service-lateral conductors, or feeder conductors that supply the main power feeder to a dwelling unit. The feeder conductors to a dwelling unit are not required to be larger than its service-entrance conductors." END QUOTE

Inferring from all of the above, is it safe to say...

that any one of a one-family, two-family, or multifamily dwelling could be characterized to be an 'individual dwelling unit' (even though being possibly two-family or multifamily?) ?

(I'm not dealing with any specific project, but rather am just trying to learn the Code and to see consistency and continuity in the wording of the Code ).

Thanks, Toolhound

 

[ToolHound]

David, Augie, OK, thanks. I see the point, i.e., the referenced Code sentence sez..."For individual dwelling units...." Okay, that removes some of the fog.

Next, related, in my 2008 NEC Handbook, for the same Code section/table (i.e., T310.15-B-6), in the shaded area commentary following the table, the writer states, quote:

"Provided a single set of 3-wire, single-phase, service-entrance conductors in raceway or cable supplies a one-framily, two-family, or multifamily dwelling, the reduced conductor size permitted by 310.15(B)(6) is applicable to the service-entrance conductors, service-lateral conductors, or feeder conductors that supply the main power feeder to a dwelling unit. The feeder conductors to a dwelling unit are not required to be larger than its service-entrance conductors." END QUOTE

Inferring from all of the above, is it safe to say...

that any one of a one-family, two-family, or multifamily dwelling could be characterized to be an 'individual dwelling unit' (even though being possibly two-family or multifamily?) ?

(I'm not dealing with any specific project, but rather am just trying to learn the Code and to see consistency and continuity in the wording of the Code ).

Thanks, Toolhound

Okay, I guess I now see that the meaning of a two-family or multifamily dwelling can not be same as meaning of an 'individual dwelling unit'. And I guess I see the meaning of the above-quoted commentary--though I would pay a dollar to the writer to re-write that part of the commentary differently, the way I would like it. Thanks. Toolhound.

 

[augie47]

If you haven't done so, spend some time in the definitions.
"Code-speak" is a different language
They are most careful to follow the defined terms and there are some subtle differences.
(outlet, receptacle, duplex, simplex, groundED, groundING, service, branch circuit, etc. )

 

[ToolHound]

See related thread at:

http://forums.mikeholt.com/showthread.php?t=152423