- Location
- Massachusetts
IMO derating should be considered for the branch circuiting in situation like this:
I was doing some IR scans today that prove that to be the case.
De-rating wire in Wireduct
- Thread starter JacobH
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I was doing some IR scans today that prove that to be the case.
But how do you determine the ampacity with the physics (enclosure v. raceway) not the same.
Is bundle on ladder-type cable tray different than bundles in wireway?
donaldelectrician
Senior Member
I was thinking the same thing ....
Derating will seem to follow more a long as in a Pan or a Traugh ....Wire way ... # of conductors across a certain area ...
There is NO Pipe restriction for heat to gather .,,,
Cotinious or not shall matter .
Don
In a sense yes, if you want to put it that way.
What I am saying is ampacity is determined outside the box (pun intended :thumbsup
and that's all that is required by the NEC.
- Location
- Illinois
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- retired electrician
Ok, then where does the section I quoted that talks about single conductors being bundled for 24" or more and not installed in a raceway apply?In a sense yes, if you want to put it that way.
What I am saying is ampacity is determined outside the box (pun intended :thumbsup
In my opinion it applies to the control panel in the pictures that are in this thread and also within vertical and horizontal wireways in a MCC.
That being said, the exception in 310.15(A)(2) would often apply to those applications.
Perhaps areas of intent... perhaps not. We may be able to go back through the proposal(s)—nka public inputs—to glean more of the intent, but a well written section requires no such action.
As to where the clause does apply... everywhere the applicable Article 310 Table conductors are bundled for 24" or more and not installed in a raceway. Nothing has changed... perhaps only your perception of the requirement.
How can we apply that section if we cannot assign an ampacity? How do we know this short portion of the circuit has a higher or lower ampacity?
Historically, have we even applied that section or have we simply ignored the ampacity for that portion of the circuit? I lean towards the latter.
- Location
- Massachusetts
You don't need a pipe to 'gather heat', all you need is a number of current carrying conductors bundled together.
- Location
- Massachusetts
In a sense yes, if you want to put it that way.
What I am saying is ampacity is determined outside the box (pun intended :thumbsup
I think this thread has jumped the shark.
Perhaps a colloquialism that I'm not familiar with... so I'll ask. What does that mean?
- Location
- Placerville, CA, USA
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- Retired PV System Designer
Rather than trying to explain it I will just refer you to a vetted Wikipedia article.
https://en.m.wikipedia.org/wiki/Jumping_the_shark
- Location
- Massachusetts
It means I think that idea you proposed is so out there I have no way to respond to it.
It's far from the first time I've mentioned it. Apparently it wasn't so far fetched the other times. :lol:
When I transition from wireway to conduit to cable tray, I expect to encounter 3 different ampacities for the conductors in the same cable... right?
If yes to the preceding, why should I not expect a different ampacity where the sheath and/or armor are stripped from the conductors and installed inside a large box... sometimes with other wires, sometimes with other equipment that generate heat?
If I run a circuit conductor entirely within a cabinet, what table do I use to determine ampacity?
If yes to the preceding, why should I not expect a different ampacity where the sheath and/or armor are stripped from the conductors and installed inside a large box... sometimes with other wires, sometimes with other equipment that generate heat?
If I run a circuit conductor entirely within a cabinet, what table do I use to determine ampacity?
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