terminal temperature rating
- Thread starter ohmboyz
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jumper
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That is one answer.
Now, could you ever put actually put a 41.6A load on the conductor?
90C is the highest terminal rating we have and 310.15(B)(3) specifically stays 110.14(C).
ohmboyz
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to the moderator:
to the moderator:
I thought I'd replied to your question. I don't see it posted here. The answer was indeed 41.6. Accordingly, the Henrys employed 310.15 B (2) (a) and my argument is that if you're going to do that
you must also apply 110.14 C . . .
to the moderator:
I thought I'd replied to your question. I don't see it posted here. The answer was indeed 41.6. Accordingly, the Henrys employed 310.15 B (2) (a) and my argument is that if you're going to do that
you must also apply 110.14 C . . .
FWIW, with all due respect... I don't see where 110.14 enters into THIS question. It would if one was sizing a feeder, branch circuit or service, yes, but when the question only asked "ampacity" the relevant factors are wire size, insulation and any derating Tables that might be applicable.
I am also an instructor (which does not make me "right") but employ the same tactics to stress to my students that "amapcity" is just what it's definition states "maximum current that a conductor can carry without exceeding it's temperature limit"..... terminations at that point don't enter into the equation.
jumper
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Look up 310.15(B). Second paragraph.
Using the table for adjustment is dependent on not exceeding terminal rating.
The terminals are specifically stated there and 110.14(C)
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jumper
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I just checked 2008, the 110.14 reference was a FPN, not anymore.
It was changed in the 2011 and became part of using the charts.
It was changed in the 2011 and became part of using the charts.
jumper
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Henry was wrong as far as the code is written now.
Under 2008, the answer could have been stated that way.
Not installed at that ampacity though.
The 2008 only had a FPN directing one to 110.14(C).
ohmboyz
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thank you everyone
thank you everyone
this string puts me in mind of a gathering of electrical engineers discussing a particular grounding strategy for a colony shelter on Mars. if there were 30 sparktrician engineers
in the room, you'd have opinions to the second harmonic
. I still maintain that once the Henry's went down the road of making an ambient temperature correction,
they must as well employ other relevant aspects of the code. Can't have it both ways unless the question was intended for word play. In that case it is of little value
to someone preparing for the exam and indeed will only confuse things, make one second guess oneself each and every time, as to the author's intent. Not good pedagogy,
either in the field or in the classroom.
thank you everyone
this string puts me in mind of a gathering of electrical engineers discussing a particular grounding strategy for a colony shelter on Mars. if there were 30 sparktrician engineers
in the room, you'd have opinions to the second harmonic
. I still maintain that once the Henry's went down the road of making an ambient temperature correction, they must as well employ other relevant aspects of the code. Can't have it both ways unless the question was intended for word play. In that case it is of little value
to someone preparing for the exam and indeed will only confuse things, make one second guess oneself each and every time, as to the author's intent. Not good pedagogy,
either in the field or in the classroom.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
this string puts me in mind of a gathering of electrical engineers discussing a particular grounding strategy for a colony shelter on Mars. if there were 30 sparktrician engineers
in the room, you'd have opinions to the second harmonic
they must as well employ other relevant aspects of the code. Can't have it both ways unless the question was intended for word play. In that case it is of little value
to someone preparing for the exam and indeed will only confuse things, make one second guess oneself each and every time, as to the author's intent. Not good pedagogy,
either in the field or in the classroom.
As I said a few posts ago, under 2008, I would have accepted the 41.6, but not now.
If you were including 110.14 as the question is written before the 2011, you would have been technically incorrect IMO.
Jumper,
excuse my thickheadness... can you try to get it through that thick head again why 41.6 is incorrect under the '11 Code since we are only asking for conductor ampacity and there is no mention of terminations,.
(I got lost in your earlier posts)
excuse my thickheadness... can you try to get it through that thick head again why 41.6 is incorrect under the '11 Code since we are only asking for conductor ampacity and there is no mention of terminations,.
(I got lost in your earlier posts)
jumper
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Since the reference to 110.14(C) is no longer a FPN and is now a part of 310.15(B), the terminals are included in using the chart.
You cannot use the multiplier to get 41.6 without agreeing to max out at possible highest terminal rating.
It was an indirect route before, now explicitly mandated.
Since a 75C termination was not mentioned, I do not have to limit the conductor to that rating, 90C is allowed. 40A. Same as conductor ampacity.
ohmboyz
Member
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- Millbrae CA, San Mateo
thickheadedness
thickheadedness
well, I do believe you've seen my photo, the one of the post office wall with a head so thick the oaks hang their limbs in shame.
As to your getting lost above, might point is quite simple. if the henry's wish to utilize anything in addition to 310.15 B 16, then
it's inconsistent to not consider 110.14 C just as much as an ambient adjustment table.
As to your point about pre 2014 and 110.14 C, I stand corrected and thanks for steering me right. The 30+ years I contracted in several different states, each with several and some, many more AHJs. All the inspectors I ever worked with preferred we work conservatively when it came to loading wires run through pipe. I have made that approach my own. I taught it to my apprentices and I teach it now to my students.
thickheadedness
well, I do believe you've seen my photo, the one of the post office wall with a head so thick the oaks hang their limbs in shame.
As to your getting lost above, might point is quite simple. if the henry's wish to utilize anything in addition to 310.15 B 16, then
it's inconsistent to not consider 110.14 C just as much as an ambient adjustment table.
As to your point about pre 2014 and 110.14 C, I stand corrected and thanks for steering me right. The 30+ years I contracted in several different states, each with several and some, many more AHJs. All the inspectors I ever worked with preferred we work conservatively when it came to loading wires run through pipe. I have made that approach my own. I taught it to my apprentices and I teach it now to my students.
jumper
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- 3 Hr 2 Min from Winged Horses
It is all really a matter of nitpicking the exact steps of what is exactly required at what stage.
The end result will end up being the same number, so in the big picture as long as the correct conductor is chosen and protected properly it is not a big deal.
ggunn
PE (Electrical), NABCEP certified
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- Austin, TX, USA
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- Consulting Electrical Engineer - Photovoltaic Systems
That's the trouble with exam questions; in an exam the scenario described can never be as detailed and consistent as what one would encounter in a real world situation. In this case, you have to consider CCC in conduit and ambient temperature derates because the pertinent conditions were explicitly called out. Terminal max temperatures were not, so do you consider them? I believe you could make a case either way, but it's a meaningless exercise because the point isn't to choose the best conductor but to get into the head of the author of the question and come up with the same answer he did in order to get the "correct" answer so that you pass the exam.
Exam world: What is the minimum size conductor you may use in <insert description of conditions>?
Real world: Can I use some of the buttload of #10 THWN-2 that I have in the truck?
Exam world: What is the minimum size conductor you may use in <insert description of conditions>?
Real world: Can I use some of the buttload of #10 THWN-2 that I have in the truck?
jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
The worst thing about the question IMO was using the temperature factor of 70F to have an adjusted ampacity of 41.6, but then not derating because of only 3 CCCs.
Somewhat of a pointless exercise IMO. The additional temperature allowances added after 1999, not sure when they were added, which do not decrease the ampacity-but increase it, were meant to offset the other derating/correction factors.
It was never intended for one to think that a 40A conductor was going to increase to 41.6A and be done.
When one leaves 310.15 and heads to 110.14 to factor in for terminal rating the ampacity is gonna be equal to or less than what was chosen from 310.15(B)(16) to start.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
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- Consulting Electrical Engineer - Photovoltaic Systems
I think that's making way too much of it. It seems to me that the point of the exercise was simply to show the two deratings and that one of them made a change to the conductor ampacity and the other didn't. There is no doubt in my mind that the majority of us are capable of doing the right thing in a real world situation, but this ain't it.
ldiehl100
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- nesquehoning, PA
The question is only asking for the ampacity of the wire, not what is used for or going to. you need to remember to read the questions and answer them as asked.
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