310.15(B)(6) Main Power Feeder.

[bphgravity]

I know this section has been beat to death, but I have a very minor question on interpretation of "Main Power Feeder."

Many homes here are installed with services on one side of the home and the lighting and applaince panelboard on the other. (split-service/extended service)

On many occasions, the contractor installes a meter/main assembly. Many times, this main section also incorporates a panelboard section usually with 6 or so spaces. From this point, the feeder is connected to feed through lugs.

On many occasions, the outside panelboard is used to serve A/C loads, and perhaps pool equipment.

Can the feeder to the inside panelboard still be considered the "main power feeder"?

 

[jwelectric]

Re: 310.15(B)(6) Main Power Feeder.

I would think of the outside panel as being a power panel not a lighting and appliance panelboard as outlined in 310.15.

For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s).

As long as no more than 10% of the overcurrent devices were 30 amps or less and utilized the grounded conductor in the outside panel then I would see no problem.

 

[donnie]

Re: 310.15(B)(6) Main Power Feeder.

I would say if it is fed from feed thru lugs , I would say it is a main power feeder, but if it is fed from a breaker from the outside that is other than the main, then it would then only be a feeder.

Donnie

 

[George Stolz]

Re: 310.15(B)(6) Main Power Feeder.

Donnie, can you explain your response?

Mike, wouldn't the status of the outside panelboard only effect the sizing of the service entrance conductors, not the feeder(s) leaving that panel?

Bryan, I would say yes, the feeder in question is still a main power feeder, based on the fact that most of the loads of the house are fed from that feeder, regardless of an A/C or pool thrown in here or there. IMO.

 

[stars13bars2]

Re: 310.15(B)(6) Main Power Feeder.

Having argued this one successfully to an appeals board, the Building Official told me that I was the first one to read him the words "Single-Phase Dwelling Services and Feeders". He was reading it as it only applied to services. This article further states "For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s)." As defined in 408.34(A) Lighting and Appliance Branch-Circuit Panelboard. A lighting and appliance branch-circuit panelboard is one having more than 10 percent of its overcurrent devices protecting lighting and appliance branch circuits. I would be hard pressed to find a panel in a residential setting that did not meet this requirement. I have heard it argued that garage panels or pool panels did not qualify because they were not part of the dwelling. I do not agree with this.

 

[George Stolz]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by stars13bars2:
Having argued this one successfully to an appeals board...

That must have felt real good. Good for you for sticking up for yourself!

I have heard it argued that garage panels or pool panels did not qualify because they were not part of the dwelling. I do not agree with this.

But the section states:

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

How does a panel that serves only a pool qualify for this section? It doesn't, IMO.

 

[jwelectric]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by georgestolz:

Mike, wouldn't the status of the outside panelboard only effect the sizing of the service entrance conductors, not the feeder(s) leaving that panel?

Should the panel on the outside contain only two pole breakers that are rated over 30 amps or are under thirty amps and do not utilize the grounded conductor then the panel is a power panelboard and not the lighting and appliance branch-circuit panelboard outlined in 310.15(B)(6).

For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s) .

once the panel on the outside is used as a lighting and appliance panelboard then the feeders will have to conform to 310.16.

 

[stars13bars2]

Re: 310.15(B)(6) Main Power Feeder.

For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s).

George
Are you saying that a pool panel feeder is not a feeder between the main disconnect and a lighting and appliance panelboard, or what? It seems simple to me when the article tells us how to apply it.

Bryan
Will your interpretation of the word main allow for more than one main feeder? The article seems to provide for more than one main feeder, which could affect the way you see this articles application.

[ February 27, 2006, 11:11 PM: Message edited by: stars13bars2 ]

 

[electrofelon]

Re: 310.15(B)(6) Main Power Feeder.

My view on this issue is that the feeder has to carrry the entire load of the service in order to use the increased ampacity. I conclude this by the commentary to 215.2 in the handbook which states,

"feeder conductors carrying the total load supplied by the service are not required to be larger than the service entrance conductors."

...And no, I don't buy the "commentary isn't code arguement"

But this meter/main with 6 circuit spaces is interesting. Pretend for a second that you agree with the "entire load of the service" theory. Does having breaker spaces available at the meter/main disallow the use of 310.15(B)(6) because of some sort of intent to add load even if they are not in at the time of inspection?

 

[stars13bars2]

Re: 310.15(B)(6) Main Power Feeder.

electro
The article says it can be feeder or feeders.

 

[George Stolz]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by jwelectric:
once the panel on the outside is used as a lighting and appliance panelboard then the feeders will have to conform to 310.16.

Mike, that does not compute.

...3-wire, single-phase service-entrance con-ductors, service lateral conductors, and feeder conductors...

How do you get a L&ABCPB at the end of a service lateral?

 

[George Stolz]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by stars13bars2:
George
Are you saying that a pool panel feeder is not a feeder between the main disconnect and a lighting and appliance panelboard, or what? It seems simple to me when the article tells us how to apply it.

Look again at the sentence fragment quoted:

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

If the feeder's (and panel's) purpose is not to serve a dwelling unit, but pool equipment instead, it is definutely not supposed to use this table.

 

[George Stolz]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by electrofelon:
...And no, I don't buy the "commentary isn't code arguement"

The handbook says so itself.

This section addressed the commentary, but doesn't say exactly what they're saying.

310.15(B)(6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services and Feeders. For individual dwelling units of one family, two-family, and multifamily dwellings, conductors, as listed in Table 310.15(B)(6), shall be permitted as 120/240-volt, 3-wire, single-phase service-entrance con-ductors, service lateral conductors, and feeder conductors that serve as the main power feeder to each dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor. For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s). The feeder conductors to a dwelling unit shall not be required to have an allowable ampacity rating greater than their service-entrance conductors. The grounded conductor shall be permitted to be smaller than the ungrounded conductors, provided the requirements of 215.2, 220.61, and 230.42 are met.

But this meter/main with 6 circuit spaces is interesting. Pretend for a second that you agree with the "entire load of the service" theory. Does having breaker spaces available at the meter/main disallow the use of 310.15(B)(6) because of some sort of intent to add load even if they are not in at the time of inspection? [/qb]

No, which is why an inspector should inspect what exists, as opposed to expecting what doesn't exist.

[ February 28, 2006, 12:02 AM: Message edited by: georgestolz ]

 

[stars13bars2]

Re: 310.15(B)(6) Main Power Feeder.

George
what is your definition of dwelling unit?

 

[david]

Re: 310.15(B)(6) Main Power Feeder.

For dwelling units, conductors, as listed in Table 310.15(B)(6), shall be permitted as 120/240-volt, 3-wire, single-phase service-entrance conductors, service lateral conductors, and feeder conductors that serve as the main power feeder to a dwelling unit

This section is only addressing the main power feeders to a dwelling unit.

Everyone seems to want to blow right by this sentence and only apply feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panel board(s)feeder(s)

Table 310.15 only applies to the feeder(s) that provide the electric to a dwelling. This is not applicable to other feeders that are not part of the supply to a dwelling. This does not apply to garage panels, swimming pool panels or any other feeder that are not part of the main supply to a dwelling

 

[electrofelon]

Re: 310.15(B)(6) Main Power Feeder.

I am aware of the disclaimer in the inside front cover that states that commentaries are not formal interpretations....So technically the commentaries are not code yes. My point is that when you are arguing a badly worded code section with an inspector, additional information on the subject that is published by the NFPA, written by their representatives, and put forth as a plain english version, has a lot of clout. Maybe in 2008 we will get the official answer?

 

[George Stolz]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by stars13bars2:
George
what is your definition of dwelling unit?

Dwelling Unit. A single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation.

Maybe we're not on the same page. My point is, imagine a feeder to an interior panel supplying all the branch circuits inside a house, supplied from a 8-space metermain.

Imagine a feeder running underground to a pool house, from the same metermain.

The feeder going to the interior panel may use 310.15(B)(6). The feeder going to the pool house cannot.

 

[jwelectric]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by georgestolz:

Originally posted by jwelectric:
once the panel on the outside is used as a lighting and appliance panelboard then the feeders will have to conform to 310.16.

Mike, that does not compute.
How do you get a L&ABCPB at the end of a service lateral?

ANY panel whether it is at the end of a service lateral, service drop or at the end of a set of feeders having more than 10 percent of its overcurrent devices protecting lighting and appliance branch circuits is a lighting and appliance panelboard.

The rule 310.15(B)(6) does not allow for the sizing of a feeder that is run from one lighting and appliance panel to another lighting and appliance panel.

The (S) at the end of the word panelboard found here;

For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s).

will allow a feeder sized by 310.15(B)(6) to supply a lighting and appliance panel from each of the one to six mains allowed in 230.71.

As far as supplying a pool house or a detached garage I see no problem with using the feeders outlined in 310.15(B)(6).
As an example let?s use a 200 amp service for this illustration. We have set three panels, one at the pool house, one at the detached garage and one in the dwelling unit. Using 310.15(B)(6) each panel would be required to be fed with a 2/0 copper or a 4/0 Aluminum or Copper-Clad Aluminum unless the pool and garage panels were rated at 200 amps and then table 310.16 would be the required table.

 

[charlie b]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by electrofelon: My view on this issue is that the feeder has to carry the entire load of the service in order to use the increased ampacity.

I agree with what I think you are saying. In an attempt to be more clear, I would say that the service conductors, or if applicable the feeder conductors, can be sized using the "increased ampacity" if those conductors carry the entire load of the dwelling unit.

Originally posted by david: This section is only addressing the main power feeders to a dwelling unit.

You have a slight mis-quote. Instead of saying "a dwelling unit," you should say "each dwelling unit." The rule applies to two-family dwelling units and to multi-family dwelling units.

Originally posted by jwelectric: The (S) at the end of the word panelboard found here;

For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s).

will allow a feeder sized by 310.15(B)(6) to supply a lighting and appliance panel from each of the one to six mains allowed in 230.71.

For the rule to apply, you need more than to simply have a lighting and appliance panel board. The feeder to that panelboard must also be the main power feeder. That "S" you mentioned is there because the rule can apply to feeders to more than one dwelling unit. The main power feeder to each dwelling unit can be sized per this rule. No other panel in any unit can be sized per this rule, because no other panel is fed from that unit's "main power feeder."

 

[jwelectric]

Re: 310.15(B)(6) Main Power Feeder.

Originally posted by charlie b:

Originally posted by jwelectric: The (S) at the end of the word panelboard found here;

For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s).

will allow a feeder sized by 310.15(B)(6) to supply a lighting and appliance panel from each of the one to six mains allowed in 230.71.

For the rule to apply, you need more than to simply have a lighting and appliance panel board. The feeder to that panelboard must also be the main power feeder. That "S" you mentioned is there because the rule can apply to feeders to more than one dwelling unit. The main power feeder to each dwelling unit can be sized per this rule. No other panel in any unit can be sized per this rule, because no other panel is fed from that unit's "main power feeder."

So what you are saying is that if I set a 400 amp service for a dwelling unit and feed two 200 amp panels that 310.15(B)(6) could not be used from the two 200 amp main breakers to the two 200 amp panels?