Average Ambient Temp

[Smart $]

...
I spelled it wrong, spell check corrected it to the wrong word.

That's pretty cool in a weird kinda way

Apparently the meaning was still clear enough as you knew what I wanted to say.

I am not unwilling to learn how to spell, I just have not been able to learn how to, I am 45 now and I don't see that changing.

Do you like to be corrected boldly in a crowed room or would you rather a more private correction?

Point taken... but you should know that you just corrected me "in public"... so we are even :grin:

Be it known I am kinda sensitive about my lack of spelling skills so if you don't mind just ignore it, or send me a PM if I make an error that is keeping you up at night. :grin:

So noted. :grin:

 

[iwire]

That's pretty cool in a weird kinda way

It also wants to change 'electricmanscott' to 'electroluminescent'.

but you should know that you just corrected me "in public"... so we are even :grin:

Dagnabit! :grin:

 

[billsnuff]

Really OT here but the human mind amazes me. I can remember circuits I ran years ago but I can not seem to remember when to use 'then' or 'than'. I can remember what code section requires the switching device for a ballasted fixture to break all ungrounded conductors but I can not remember someones name I meet minutes ago.

I sometimes feel like 'Rainman' I am very bright in some areas and an idiot in other areas.

You know, Bob, it seems that our brains are all wired a little differently. Diversity is what make life so amazing, and this forum a great place to hang out, as it is the epitomy of diversity, as is the trade.

 

[M. D.]

.... Does anyone know if this ambient temp. thing has ever been brought up as a ROP and what happened to it if it had? I would be curious.

For what it is worth...

_______
6-51 Log #3150 NEC-P06 Final Action: Accept in Principle
(310.15(B)(2)(c))
____________________________________________________________
TCC Action: It was the action of the Technical Correlating Committee that
further consideration be given to the comments expressed in the voting.
This action will be considered by the panel as a public comment.
Submitter: Travis Lindsey, Travis Lindsey Consulting Services
Recommendation: Add 310.15(B)(2)(c) to read:
(c) Conduits Exposed to Sunlight on Rooftops. Where conductors or cables
are installed in conduits exposed to direct sunlight on or above rooftops, the
adjustments shown in Table 310-15(B)(2)(c) shall be added to the outdoor
temperature to determine the applicable ambient temperature for application of
the correction factors in Tables 310.16 and 310.18.

Table 310.15(B)(2)(c) Ambient Temperature Adjustment for Conduits
Exposed to Sunlight On or Above Rooftops
Distance Above Roof Temperature Adjustment
On roof, up to and including
13 mm (? in.) above roof 33 ?C (60 ?F)
Above 13 mm (? in.), up to and
including 90 mm (3-? in.) above roof 22 ?C (40 ?F)

Panel Meeting Action: Accept in Principle
Add 310.15(B)(2)(c) to read:
(c) Conduits Exposed to Sunlight on Rooftops. Where conductors or cables
are installed in conduits exposed to direct sunlight on or above rooftops, the
adjustments shown in Table 310-15(B)(2)(c) shall be added to the outdoor
temperature to determine the applicable ambient temperature for application of
the correction factors in Tables 310.16 and 310.18.

Table 310.15(B)(2)(c) Ambient Temperature Adjustment for Conduits
Exposed to Sunlight On or Above Rooftops
Distance Above Roof to
Bottom of Conduit
Temperature Adder
C? F?
0 thru 13 mm (? in.) 33 60
Above 13 mm (? in.), thru 90 mm (3-? in.) 22 40
Above 90 mm (3-? in.), thru 300 mm (12 in.) 17 30
Above 300 mm (12 in.), thru 900 mm (36 in.) 14 25

Panel Statement: The revisions to the Table improve clarity since the values
shown are temperature adders for each set of numeric units and not direct
conversions from ?C to ?F.
Number Eligible to Vote: 11
Ballot Results: Affirmative: 9 Negative: 2
Explanation of Negative:
HUDDLESTON, JR., R.: This proposal should have been rejected. The panel
did not really examine the implications of this proposal; rather, they blindly
accepted that there is merit to de-rating ampacity in conduits on rooftops due to
one elaborate and ?scholarly? study. The real implications are onerous - a
derating to 33 percent of Table 310.16 ampacity for conductors run across the
roof (the example presented by this panel member to the panel) is completely
unwarranted. What is the problem that we are trying to fix? Is there any
documented evidence of failures of conductors installed on rooftops? None was
presented to the Code Panel.
Industrial users of the NEC will be affected in their installation and wiring of
rooftop blowers and HVAC units, as well as other rooftop electrical devices.
Benefits to the copper industry are obvious. Benefits to users of conductors are
much less so. The bottom line is that this proposal stands to make it much more
expensive to install equipment on rooftops without any documented safety
benefit.
MCCLUNG, L.: Personal experience with conductors installed in metallic
conduits across rooftops during 41 years of continuous service at facilities
ranging from Edmonton, Alberta to Ponce, Puerto Rico, without a failure of
such 600V conductors leads to the conclusion that normal industrial
installations using the allowable ampacities with existing derating already in
the NEC are safe and reliable.
Comment on Affirmative:
KENT, G.: I agree with this proposal, but feel it necessary to point out
averaging was used for the ambient temperature in the study. The Code should
reference this averaging to keep inspectors/local jurisdictions from using the
hottest day on record as the temperature to begin a de-rating factor from.
LAIDLER, W.: I agree with the panel?s action to accept this proposal in part
based on the technical substantiation provided by the submitter. The panel
should have added language that would give guidance to how the maximum
outside ambient temperature should be determined. An AHJ could take the
maximum temperature of the hottest day of the year for that location and
require that 30?F be added to that temperature to arrive at the temperature in
which the correction factors in Tables 310.16 and 310.18 would be applied. I
do not believe that the submitter intended that a maximum instantaneous value
be used when applying this new section. It was stated in the submitter?s
substantiation that an average or median temperature value was used in
experiments to avoid using extreme temperatures. A FPN could be added along
with this new section making reference to several different ways that could be
used in determining the maximum average temperature for a specific location.
ZIMNOCH, J.: The submitter should submit a listing of temperatures for
various cities.

 

[Karl H]

My spelling and grammar sucks. I can live with that but, I'm more interrested
in the answer to which Ambient Temp value we should use for roof top
conductors. Average or Max. I want to look super smart in my next
design meeting, when exposed roof top conduits will be installed.:smile:

 

[Twoskinsoneman]

Hey I know we got off track but iwire, what do you think of the comments in the partial ROP I posted in #22 and M.D re-posted in #44?

 

[M. D.]

The more I read this section ,. the more I realize how poorly written it is..

.

....shall be added to the outdoor
temperature to determine the applicable ambient temperature for application of
the correction factors in Tables 310.16 and 310.18.

so I'll be choosing a chilly day I guess

 

[Karl H]

The more I read this section ,. the more I realize how poorly written it is..

.
so I'll be choosing a chilly day I guess

I feel the same way. IMO it "should" be the max but then again
should the duration of the Max also be a factor. If you live in a cold climate
your going to spend a lot of money on larger conductors. When the max
Temp may be only a month or two.

 

[Karl H]

I just checked ,the average temp in San Diego is 66 degrees.
Now I'm starting to think I'm going to look like an idiot if I start de-rating
my conductors per the NEC with an average temp of 66. Now
if I were back in Texas I would understand and make provisions but, here
I think I'm just going to look like a geek. :grin:

 

[iwire]

Hey I know we got off track but iwire, what do you think of the comments in the partial ROP I posted in #22 and M.D re-posted in #44?

I don't understand, I thought I responded to this in post 25? :-?

I can accept that the CMP does not want us to use the one time max temp but the fact they do not give any indication of how they do want us to determine the average outdoor temp it is entirely up to the AHJ to figure it out.


That said I sure would like another example in the NEC where we are not to use the worst case scenario when determining condutor ampacity.