# Min. Size conductor for sub panel



## Wireless (Jan 22, 2007)

Gamit said:


> It would be 6 AWG correct? 230.202
> This would be for all dwellings,Apt,etc


That is the minimum, size service, not a sub-panel.


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## Dennis Alwon (May 9, 2009)

Gamit said:


> It would be 6 AWG correct? 230.202
> This would be for all dwellings,Apt,etc


230 is for services not sub panels. I can have a 30 amp subpanel if it is sufficient for the load .


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## Gamit (Dec 30, 2009)

Dennis Alwon said:


> 230 is for services not sub panels. I can have a 30 amp subpanel if it is sufficient for the load .


I thought so but was told by three different people that you can fuse your sub at whatever the load is,but you had to use number 6 min conductor. I guess if that was true it would be located in feeders somewhere and could not find it.


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## Dennis Alwon (May 9, 2009)

Gamit said:


> I thought so but was told by three different people that you can fuse your sub at whatever the load is,but you had to use number 6 min conductor. I guess if that was true it would be located in feeders somewhere and could not find it.


Have you looked at the article that you stated. Art. 230.202 is not only for services but for services over 600V. 

When using the code book it is important to read the headings and sections of a specific article.


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## Gamit (Dec 30, 2009)

I did notice after posting  I guess when you here something from three established electricians you blindly look for something that does not exist.


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## Gamit (Dec 30, 2009)

Maybe I should of explained the application when I was told this. We were putting this sub panel in a detached garage. So it was a outside feeder and 225.39 (D) would explain there reasoning.


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## Dennis Alwon (May 9, 2009)

Gamit said:


> Maybe I should of explained the application when I was told this. We were putting this sub panel in a detached garage. So it was a outside feeder and 225.39 (D) would explain there reasoning.


i wondered about that however, don't even try to understand that section as it only requires the disconnect to be rated 60 amps not the conductors.


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## Gamit (Dec 30, 2009)

Dennis Alwon said:


> i wondered about that however, don't even try to understand that section as it only requires the disconnect to be rated 60 amps not the conductors.


If you need a 60 Amp disco then you must size the conductor accordingly so a #6 conductor would be needed. So they were correct!


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## RePhase277 (Feb 5, 2008)

Gamit said:


> If you need a 60 Amp disco then you must size the conductor accordingly so a #6 conductor would be needed. So they were correct!


No, the disco is required to be at least 60 A, but the circuit itself could be 30 A fed by #10 conductors.


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## Gamit (Dec 30, 2009)

InPhase277 said:


> No, the disco is required to be at least 60 A, but the circuit itself could be 30 A fed by #10 conductors.


Then what's the purpose of using a 60 amp disconnect then? You should be able to use a 30. Explain why


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## erics37 (May 7, 2009)

Gamit said:


> If you need a 60 Amp disco then you must size the conductor accordingly so a #6 conductor would be needed. So they were correct!


A 60 amp disconnect means that the disconnect is rated to have up to 60 amps go through it.

You can put whatever size circuit you want, up to 60 amps, on that disconnect.

If you have a 60 amp _circuit breaker_, which is an overcurrent protection device, then you usually have to put the appropriate size conductors on it.

A disconnect is just a disconnect. If you had a 23,942,034,820,934 amp disconnect you could still run a 20 amp circuit through it.


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## wirenut71 (Dec 5, 2010)

Read that article again. It says that the *disconnecting means* shall have a rating of not less than 60 amps.


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## erics37 (May 7, 2009)

Gamit said:


> Then what's the purpose of using a 60 amp disconnect then? You should be able to use a 30. Explain why


Because like Dennis said, 225.39(D) requires that the minimum rating of a feeder disconnecting means for a building supplied by a feeder is 60 amps.


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## miller_elex (Jan 25, 2008)

Dude, I'm confussed now,

lordy lordy lordy!


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## erics37 (May 7, 2009)

Okay so here's the gist of it:


Calculate the load to be served of the detached building per Article 220. If your calculated load is, say, 36 amps, then a 40 amp circuit breaker with #8 copper (minimum) conductors would be adequate.
Select the proper size circuit breaker for this load.
Select the proper size conductors for this circuit breaker. If you want to have some capacity for future expansion then size your conductors up a bit.
If the detached building has a subpanel in it, make sure the subpanel is of sufficient rating for the feeder you will be supplying it with.
Your detached building requires a disconnecting means rated no less than 60 amps. That means the switching device(s) that shuts off the power supply at the detached building... not the overcurrent device that supplies the feeder from the original panel in the main building.
I think that's about it, if I'm wrong about something someone please correct me.


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## Gamit (Dec 30, 2009)

erics37 said:


> A 60 amp disconnect means that the disconnect is rated to have up to 60 amps go through it.
> 
> You can put whatever size circuit you want, up to 60 amps, on that disconnect.
> 
> ...


I understand the function of a disconnect and a OCD. I'm just wondering how the NEC geniuses came up with 60 as the minimum disconnecting means?


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## erics37 (May 7, 2009)

Gamit said:


> I understand the function of a disconnect and a OCD. I'm just wondering how the NEC geniuses came up with 60 as the minimum disconnecting means?


I dunno. That's only for a detached building supplied by a feeder. If it's just one or two branch circuits then the disconnect ratings are lower.


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## Gamit (Dec 30, 2009)

erics37 said:


> I dunno. That's only for a detached building supplied by a feeder. If it's just one or two branch circuits then the disconnect ratings are lower.


Saw that 15 and 30


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