# Using Table 310.16(b)(6) to size gen wires



## Salvatoreg02 (Feb 26, 2011)

Can this table be used to size the conductors from a service rated 200amp ATS to the generator, even though it specifically states it is for single phase dwelling services and feeders?


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## Bulldog1 (Oct 21, 2011)

The generator FEEDS the dwelling. That table is from the 2011 NEC. Aren't you under 2005?


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## Salvatoreg02 (Feb 26, 2011)

Bulldog1 said:


> The generator FEEDS the dwelling. That table is from the 2011 NEC. Aren't you under 2005?


So is that a yes or no answer?

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## Bulldog1 (Oct 21, 2011)

Salvatoreg02 said:


> So is that a yes or no answer?
> 
> Sent from my iPhone using ET Forum



It's a yes if the generator backs up all of the load of the dwelling.


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## McClary’s Electrical (Feb 21, 2009)

Bulldog1 said:


> It's a yes if the generator backs up all of the load of the dwelling.


 
The wording in 05 specifically says 3 wire. Going to check 08 but 05 wording says you're wrong.


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## McClary’s Electrical (Feb 21, 2009)

08 wording is the same.

*Table 310.15(B)(6) Conductor Types and Sizes for*
*120/240-Volt,* 3-Wire*, Single-Phase Dwelling Services and*
*Feeders. Conductor Types RHH, RHW, RHW-2, THHN,*
*THHW, THW, THW-2, THWN, THWN-2, XHHW,*
*XHHW-2, SE, USE, USE-2*
*Conductor (AWG or kcmil)*
*Service or Feeder*
*Rating (Amperes) Copper*
*Aluminum or*
*Copper-Clad*
*Aluminum*
100 4 2
110 3 1
125 2 1/0
150 1 2/0
175 1/0 3/0
200 2/0 4/0
225 3/0 250
250 4/0 300
300 250 350
350 350 500
400 400 600​

ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 
​​*310.15*

2008 Edition ​

​​NATIONAL ELECTRICAL CODE *70*–147
Copyright National​


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## B4T (Feb 10, 2009)

(7) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
and Feeders. For individual dwelling units of onefamily,
two-family, and multifamily dwellings, conductors,
as listed in Table 310.15(B)(7), 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 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 between the
main disconnect and the panelboard that supplies, either by
branch circuits or by feeders, or both, all loads that are part
or associated with the dwelling unit. 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.

It is really 4-wire.. 2011


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## McClary’s Electrical (Feb 21, 2009)

B4T said:


> (7) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
> and Feeders. For individual dwelling units of onefamily,
> two-family, and multifamily dwellings, conductors,
> as listed in Table 310.15(B)(7), shall be permitted as
> ...


 
Good catch Old man:thumbsup:


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## Salvatoreg02 (Feb 26, 2011)

So, it seems as though all are in agreement that this chart shall be used for sizing conductors related to any residential generator? Be right back!


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## BBQ (Nov 16, 2010)

Salvatoreg02 said:


> So, it seems as though all are in agreement that this chart shall be used for sizing conductors related to any residential generator? Be right back!


No, not 'any' residential generator, only a residential generator that supplies the entire house.

If the generator just supplies some of the loads you must use the normal table.


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## Bulldog1 (Oct 21, 2011)

BBQ said:


> No, not 'any' residential generator, only a residential generator that supplies the entire house.
> 
> If the generator just supplies some of the loads you must use the normal table.



I know I posted this at least 3 times yet he still doesn't get it.......:no:

I am having a hard time believing anyone could be this hardheaded. Even my bulldog is not that stubborn.....:blink:


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## Salvatoreg02 (Feb 26, 2011)

I think their's lack in communicating that if the generator is the primary source of power then this table can be used.

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## Fibes (Feb 18, 2010)

Bulldog1 said:


> I know I posted this at least 3 times yet he still doesn't get it.......:no:
> 
> I am having a hard time believing anyone could be this hardheaded. Even my bulldog is not that stubborn.....:blink:


It's not being hardheaded, it's more simple than that. When there is a true lack of understanding on a persons part, they just keep asking questions and even try to manipulate the answers to fit their desired outcome.


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## Bulldog1 (Oct 21, 2011)

Salvatoreg02 said:


> I think their's lack in communicating that if the generator is the primary source of power then this table can be used.
> 
> Sent from my iPhone using ET Forum




It has nothing to do with the generator being the primary source of power.....( BTW WTF does primary source of power even mean? :001_huh


IF THE GENERATOR BACKS EVERY FREAKING CIRCUIT IN THE SERVICE PANEL....AND ONLY IF IT DOES CAN YOU USE 310.15(b)(6)


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## BBQ (Nov 16, 2010)

I agree with Bulldog.

In NEC terms it must be the 'main power feeder' to a dwelling unit.


The following directly from the NEC 310.15(B)(6) or (7) depending on the code cycle.



> For application of this section, the main power feeder shall be the feeder between the main disconnect and the panelboard that supplies, either by branch circuits or by feeders, or both, *all loads that are part or associated with the dwelling unit.*


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## Bulldog1 (Oct 21, 2011)

BBQ said:


> I agree with Bulldog.
> 
> In NEC terms it must be the 'main power feeder' to a dwelling unit.
> 
> ...




I believe 2005 said "If the majority of the loads or something similar......" but was changed to the wording you posted in 2008.


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## BBQ (Nov 16, 2010)

Bulldog1 said:


> I believe 2005 said "If the majority of the loads or something similar......" but was changed to the wording you posted in 2008.


It said 'main power feeder' but it did not really define what that meant. The changes added the wording describing what a main power feeder was.

The code did not change, the intent had been the same for many code cycles but people were ignoring it.

Here it is in 2002, as far back as I have pdfs for.



> (6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
> and Feeders. 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
> ...


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