# conductors feeding a disconnect



## moss4330 (Nov 2, 2014)

Hey all Im having a hard time finding the Canadian electrical code rule for the feeding of a disconnect with conductors rated of the amperage of the disconnect? I have a contractor hired on my site which has fed 4 100a disconnects for 4 xfmrs but he has used the # 4 to feed the line side of the disconnects from the splitter. anyone ? Thanks all


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## ponyboy (Nov 18, 2012)

I know you're in Canada but I would think you don't have to match the ampacity rating of the disconnect, you just can't exceed it


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## moss4330 (Nov 2, 2014)

ponyboy said:


> I know you're in Canada but I would think you don't have to match the ampacity rating of the disconnect, you just can't exceed it


In Canada from say a 400 amp splitter we have to run conductors that are rated for at least 100 amps if we are feeding a 100 amp disconnect, after the fuses obviously we run conductors for the fuse size. Im only looking for the code rule so as I can explain the defect to the contractor. Thanks


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## ponyboy (Nov 18, 2012)

moss4330 said:


> In Canada from say a 400 amp splitter we have to run conductors that are rated for at least 100 amps if we are feeding a 100 amp disconnect, after the fuses obviously we run conductors for the fuse size. Im only looking for the code rule so as I can explain the defect to the contractor. Thanks



Right...yeah I'd like to see that too. That's ridiculous.


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## macmikeman (Jan 23, 2007)

Wh at voltage is the primary supply of the transformers that you are referencing? If this is 277/480 or some Canadian way up there voltage there might not be any problem.

We need details.


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## ponyboy (Nov 18, 2012)

macmikeman said:


> Wh at voltage is the primary supply of the transformers that you are referencing? If this is 277/480 or some Canadian way up there voltage there might not be any problem.
> 
> 
> 
> We need details.



He's saying you can't feed a 100 amp rated disco with a 60 amp rated feeder. You won't find any such rule in the NEC but I'm not surprised if they have one up there. I still doubt it though


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## moss4330 (Nov 2, 2014)

ponyboy said:


> Right...yeah I'd like to see that too. That's ridiculous.


So If a client asks you to install a 400 amp service with 4 100 amp fusible disconnects for future use what size wire would you run from the splitter to the line side of the 100 amp disconnects?


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## ponyboy (Nov 18, 2012)

moss4330 said:


> So If a client asks you to install a 400 amp service with 4 100 amp fusible disconnects for future use what size wire would you run from the splitter to the line side of the 100 amp disconnects?



Well in that situation yes I would pull #3 cu for 100 amps. I was under the impression you were saying that since the ampere rating of the disconnect was 100 amps that ampacity of the feed conductors MUST be 100 amps. Now if the loads were 80 amps then I would pull #3 cu but still use the 100 amp disconnect. At least I can do that here that is. Sounds like you got robbed though


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## Pete m. (Nov 19, 2011)

There was a thread very similar to this not too long ago but I can't seem to find it.

IIRC, someone did post some code (CEC).

Pete


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## Pete m. (Nov 19, 2011)

Found the thread but there isn't as much code wise in it as I thought.

http://www.electriciantalk.com/f31/wire-disconnect-rating-fuse-rating-72336/?highlight=disconnect+feeder

Pete


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## Scott_w (Jan 1, 2012)

Rule 14-100is summarized as follows:

*If the Tap conductor length is 0-7.5M *

1>1/3 the larger conductors ampacity (conductor feeding the tap)
2>The amp rating of the over current device being fed by the tap conductor.

(use the larger of the 2)

*If the tap conductor is 0-3M*

*CHOICE #1*
1>1/3 the larger conductors ampacity (conductor feeding the tap)
<or>
2>The amp rating of the over current device being fed by the tap conductor.
_*USE THE LARGER OF 1 or 2*_

*CHOICE #2*
The amp rating of the equipment being fed by the tap conductor.

**Now in this instance of 0-3M you select the smallest choice #1 or #2 to determine the smallest ampere rating of the tap conductor.


So as others have said more info is needed... ie length, cable installed, insulation rating etc


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## moss4330 (Nov 2, 2014)

*U guys rock*

14-100-c-2
Thanks guys your the best!!! I knew it was in there I just couldn't find the rule. 32 years of doing this I seem to have forgotten more than I have learned:thumbup::thumbup::thumbup:


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## ponyboy (Nov 18, 2012)

moss4330 said:


> 14-100-c-2
> Thanks guys your the best!!! I knew it was in there I just couldn't find the rule. 32 years of doing this I seem to have forgotten more than I have learned:thumbup::thumbup::thumbup:



I'm not sure the rule cited bolsters your stance or not. But for sure if you asked for 100 amp feeders and didn't get them you've got issues


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