newsletter 11/17/14 error?

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mjmike

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Sent customer support an email on the 11/17/14 newsletter for Bundling adjustment example #2. Here was the newsletter question:

"? Ampacity Adjustment Example 2
Question: What?s the adjusted ampacity of four 1 THWN conductors in a raceway?
(a) 120A (b) 104A (c) 29A (d) 32A
Answer: (b) 104A Adjusted
Ampacity = Table 310.15(B)(16) Ampacity x
Bundled Ampacity Adjustment Factor from Table 310.15(B)(3)(a)
1 THWN is rated 130A at 90 DegrC [Table 310.15(B)(16)]
Adjustment factor for four current-carrying conductors is 0.80 [Table 310.15(B)(3)(a)]
Adjusted Ampacity = 130A x 0.80
Adjusted Ampacity = 104A"

I am using the 2011 NEC table and doubt the 2014 changed, but either they are referring to #2 THWN-2, or #1 THWN @ 75 degrees C because #1 THWN-2 at 90 degree C starts at 145 degrees and the answer would be 116 degrees derated. Am I missing something??
 
Didn't see the newsletter but,

THWN is rated for 75?C.
THWN-2 is rated for 90?C.

or am I missing something.

If that is copied directly from the newsletter than I'd say proof-reading error. Because the math works out.

Speaking of proof-reading I think you should go check your post because it looks like you've confused amps and degrees in your post.
 
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Got a confirmation from Mike Holt representative. The 90 degree is a typo and the question is based on the 75 degree column.
 
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