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Joined: Oct 2000
Posts: 2,749
Member
Here's a question that was on an electrician's test. The student answered (d) as the correct one. He was told he was incorrect?

What is the correct answer?

Note: See 110-5, and that no insulation, or conductor material was given?

Question No. 9: Which of the following statements about the general requirements for number 6 conductors is true?

(a) It is required to be terminated at 75 degree C ampacity.

(b) It is required to be terminated at 60 degree C ampacity.

(c) It must have insulation rated 60 degree C ampacity.

(d) It must have insulation rated 75 degree C ampacity.

I will invite the student to join this board so he can add more on this subject.


Joe Tedesco, NEC Consultant
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Joined: Sep 2001
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T
Junior Member
The general rule would apply and the only possible answer with what is given is that it needs to be terminated at 60 degrees.

Joined: May 2001
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G
Member
I tend to agree, with no further info I would have to apply 110-14 C and assume (dangerous, huh ? especially on a test) that it would be terminated in unknown terminations, which would mean you have to assume under 100 amps and terminate it at it's 60 deg. C ampacity. If that was the wording with no further explanation, it was broad based, KINDA vague.

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I tend to agree with the other two posts.

Since there is no Insulation type given, this could be anything from TW [60 degree C], to THHN [90 degree C].

Since we can use Conductors with THHN Insulation and rate them at 60 degrees C for wet locations, or 90 degrees C for dry locations [for ampacity adjustments], this would exclude (c) and (d).

Since we are to use the 60 degree ampacity column in 310-16 for conductors sized #14 through #1, this would eliminate (a).

By default, the only remaining answer would be (b).

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Joined: Oct 2000
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Joe,

I think it's a poorly worded question and could be viewed different ways.

I think that it would be (b) or (c) depending on what they were looking for.
I would lean torward (c) with 60C as a Minimum rating.

Question:

Is 75C wiring also rated 60C ?


Bill


Bill
Joined: Oct 2000
Posts: 2,749
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Bill:

I agree that the question may be poorly worded. Seems like we all agree on the correct answer.


Joe Tedesco, NEC Consultant
Joined: Oct 2000
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Joe,

I'm not sure which answer we're all agreeing on. I see (b)s and my (c)answer. (Or, do you mean that we all agree it is poorly worded)

Does the NEC consider a 75C conductor as also being rated 60C ? like dual-rated?

Bill


Bill
Joined: Mar 2001
Posts: 2,056
R
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Bill,
I understand that the temp. rating is the MAXIMUM temp. that the insulation can withstand without beginning to physically degrade. Therefore, if it is rated for 75 deg., any temp below is acceptable.

Joined: Oct 2000
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Redsy,

Yes, I understand. I was just wondering if that would be proper terminology to state that 75C wire is also rated 60C. I'm just asking for the purposes of this test Question but I guess that it doesn't really matter.

Joe,

You didn't tell us what was considered to be the correct answer??

Bill


Bill
Joined: Nov 2001
Posts: 1
A
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Bill,
The answer is "C" !!!

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