# Extending circuits for panel change



## NDC (Jan 12, 2016)

I have to replace a fuse panel soon and extending all of the circuits is required. Instead of using like three stove boxes for junctions, I'm wondering if a trough is available in a smaller size. I wouldnt know what to call it. A mini splitter?


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## HackWork (Oct 2, 2009)

In these situations I have used 4X4X24" troughs. Mount a ground bar or two to the back to make it easier. 

If you have a lot of circuits then a 6X6X24" might be better. Some people like to use a 12X12X4" box instead. It all depends on the amount of circuits and placement of the box.


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## Kevin (Feb 14, 2017)

Why not something like a 12x12x4 pull box or similar?

Sent from my new phone. Autocorrect may have changed stuff.


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## NDC (Jan 12, 2016)

HackWork said:


> In these situations I have used 4X4X24" troughs. Mount a ground bar or two to the back to make it easier.
> 
> If you have a lot of circuits then a 6X6X24" might be better. Some people like to use a 12X12X4" box instead. It all depends on the amount of circuits and placement of the box.



Yeah have about 4" of room for the box, good tip for the ground bars.




Kevin_Essiambre said:


> Why not something like a 12x12x4 pull box or similar?



No room in for anything larger than 5" in height. Have room for 24" wide though.


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## Navyguy (Mar 15, 2010)

Here is a few samples for you...

Cheers
John


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## NDC (Jan 12, 2016)

Navyguy said:


> Here is a few samples for you...
> 
> Cheers
> John



Thanks for posting those pics. Do you just run a 1" or 1-1/4" conduit typically or do you actually size the conduit for the amount of wires?


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## zac (May 11, 2009)

Are those conduits over 2'? The inspectors here would call it out (possibly) for wire derating. 

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## NDC (Jan 12, 2016)

zac said:


> Are those conduits over 2'? The inspectors here would call it out (possibly) for wire derating.
> 
> Sent from my SM-G950U using Tapatalk



If they're sized properly, whats the problem?


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## zac (May 11, 2009)

NDC said:


> If they're sized properly, whats the problem?


In the U.S. table 310.15(b)(3)(a)
4 to 6 conductors you'll have to derate 80% which isn't a big deal. But 7-9 the wire needs to be derated at 70% and so on. Doesn't matter if it's in a 4" pipe. 
In residential I'm not too concerned unless it's dedicated circuits that could be on call for long periods of time. 

Sent from my SM-G950U using Tapatalk


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## joe-nwt (Mar 28, 2019)

zac said:


> In the U.S. table 310.15(b)(3)(a)
> 4 to 6 conductors you'll have to derate 80% which isn't a big deal. But 7-9 the wire needs to be derated at 70% and so on. *Doesn't matter if it's in a 4" pipe.*
> In residential I'm not too concerned unless it's dedicated circuits that could be on call for long periods of time.
> 
> Sent from my SM-G950U using Tapatalk


Another oddity of the electrical code IMHO. All the wires in the entire panel end up in a 4"x14" rectangular pipe (panel) but 7 wires in a 4" conduit is uber dangerous.


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## The_Modifier (Oct 24, 2009)

Navyguy said:


> Here is a few samples for you...
> 
> Cheers
> John


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## emtnut (Mar 1, 2015)

Navyguy said:


> Here is a few samples for you...
> 
> Cheers
> John



Nice wiring work there Navy !


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## Dennis Alwon (May 9, 2009)

zac said:


> In the U.S. table 310.15(b)(3)(a)
> 4 to 6 conductors you'll have to derate 80% which isn't a big deal. But 7-9 the wire needs to be derated at 70% and so on. Doesn't matter if it's in a 4" pipe.
> In residential I'm not too concerned unless it's dedicated circuits that could be on call for long periods of time.
> 
> Sent from my SM-G950U using Tapatalk


70% will not affect smaller wires like 12 and 14 gauges. 

12 thhn is rated 30 amps at 90C. 70% of 90 is still 21 amps
14 awg is good for 25 amps at 90C-- 70% of 25 is 17.5 amps


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## Navyguy (Mar 15, 2010)

NDC said:


> Thanks for posting those pics. Do you just run a 1" or 1-1/4" conduit typically or do you actually size the conduit for the amount of wires?


I generally use an 1.25 conduit just because it is common and handy. Usually they are 24" or less, so I never worry about derating the wire.

Cheers
John


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## Navyguy (Mar 15, 2010)

zac said:


> Are those conduits over 2'? The inspectors here would call it out (possibly) for wire derating.


I never derate because the wires are all less then 24" (well most of the time).

I think it is an Ontario rule / amendment to 12-910 that we don't derate for nipples or short sections of conduit less then 24". I don't remember the exact rule or wording...

Cheers
John


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## The_Modifier (Oct 24, 2009)

Navyguy said:


> I think it is an Ontario rule / amendment to 12-910 that we don't derate for nipples


Never, never, NEVER derate nipples- you'll end up sleeping on the couch.:surprise::wink:


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## Dennis Alwon (May 9, 2009)

Navyguy said:


> I never derate because the wires are all less then 24" (well most of the time).
> 
> I think it is an Ontario rule / amendment to 12-910 that we don't derate for nipples or short sections of conduit less then 24". I don't remember the exact rule or wording...
> 
> ...


Same in the Nec


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## emtnut (Mar 1, 2015)

The_Modifier said:


> Never, never, NEVER derate nipples- you'll end up sleeping on the couch.:surprise::wink:



I don't derate nipples, but I'm still on the couch :sad: .. what gives ????


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## zac (May 11, 2009)

Dennis Alwon said:


> 70% will not affect smaller wires like 12 and 14 gauges.
> 
> 
> 
> ...


The problem is that the breaker is rated at 60-75c. So even though the wire is capable 
the inspector will require the 60 degree table be used. 

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## MotoGP1199 (Aug 11, 2014)

zac said:


> The problem is that the breaker is rated at 60-75c. So even though the wire is capable
> the inspector will require the 60 degree table be used.
> 
> Sent from my SM-G950U using Tapatalk


For purposes of de-rating only you can absolutely use the wires insulation rating. You will have to use the 60* or 75* column for everything else depending on the equipment/breaker. 

Edit: He's just saying the wire after being de-rated for the insulation is still above the 60* column so the wire will still work for #12 at 20 amp and #14 at 15 amp when de-rating is applied at that ratio.


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## MotoGP1199 (Aug 11, 2014)

110.14 (C) "Temperature Limitations. The temperature rating associ‐
ated with the ampacity of a conductor shall be selected and
coordinated so as not to exceed the lowest temperature rating
of any connected termination, conductor, or device. *Conduc‐
tors with temperature ratings higher than specified for termi‐
nations shall be permitted to be used for ampacity adjustment,
correction, or both.*"


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## NDC (Jan 12, 2016)

Navyguy said:


> zac said:
> 
> 
> > Are those conduits over 2'? The inspectors here would call it out (possibly) for wire derating.
> ...


Cant find this less than 24" rule. If you find it please let me know.


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## Navyguy (Mar 15, 2010)

Try 4-004 (13)



CEC Section 4 said:


> 13) Where multi-conductor cables are run in contact for distances greater than 600 mm, the ampacity of the conductors shall be corrected by applying the correction factors from Table 5C based on the total number of conductors in the cables.


Cheers
John


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## eddy current (Feb 28, 2009)

Navyguy said:


> Try 4-004 (13)
> 
> 
> 
> ...


That rule does not say we do not have to derate conductors in short raceways.

That rule applies to multi conductor cables run in contact with each other.


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## MikeFL (Apr 16, 2016)

Around here we've always converted the old panel to be the j-box and make up all the connections in there, then run to the new box. 

In the pictures posted in this thread it does look nice to add a wireway.


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## Navyguy (Mar 15, 2010)

eddy current said:


> That rule does not say we do not have to derate conductors in short raceways.
> 
> That rule applies to multi conductor cables run in contact with each other.


You are right. I am sure there is another rule but I cannot seem to find it now.

Perhaps it is an old rule, or one that is made up...

I would have bet the farm that there was something that stated that conduits and fittings used for mechanical protection and joining electrical equipment less then 24" were not subject to derating rules; that is not just something I would have made up, but perhaps it is rule that no longer exists.

Maybe a old 2012 rule or earlier?

Regardless of the fact, I have never once been called for derating on any of the installations pictured or the tons of troughs used for control wiring, etc that I have installed. Hard to believe that I have been that lucky for 30 years...

I will look more in-depth when I have some time.

Cheers
John


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## NDC (Jan 12, 2016)

Navyguy said:


> You are right. I am sure there is another rule but I cannot seem to find it now.
> 
> Perhaps it is an old rule, or one that is made up...
> 
> ...



I'm pretty sure you're right with this one. I remember a trick question in school about what size to use for nippling 2 panel tubs together and apparently if the nipple was short enough, it could be packed full of wires.


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## eddy current (Feb 28, 2009)

@Navyguy there is a code that says conduit fill does not apply to short sections used for mechanical protection of open wiring, maybe your thinking of that one? 12-910(2)

I will check the old books and see if there was something about ampacities that has been removed as well.


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## 99cents (Aug 20, 2012)

Section 13


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## eddy current (Feb 28, 2009)

eddy current said:


> @Navyguy
> 
> I will check the old books and see if there was something about ampacities that has been removed as well.



I went back as far as 1972 in section 4 and did not find anything


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