# Thread: Electrical Exam Prep Help?

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## Electrical Exam Prep Help?

Is this the correct forum to seek help getting through the Mike Holt 2017 NEC Exam Preparation Course?

3. I assume this is what you are questioning. It is pretty straightforward but how one is expected to enforce this is another question

110.14(D) Installation. Where a tightening torque is indicated as a
numeric value on equipment or in installation instructions
provided by the manufacturer, a calibrated torque tool shall be
used to achieve the indicated torque value, unless the equipment
manufacturer has provided installation instructions for
an alternative method of achieving the required torque.

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Originally Posted by infinity
Preparing to take a Master Electrician Exam, just looking for some help along the way. I'll be posting questions as needed to get through the course, currently in Unit 6 - Conductor Sizing and Protection Calculations.

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Originally Posted by Dennis Alwon
I assume this is what you are questioning. It is pretty straightforward but how one is expected to enforce this is another question
That's my user name, not a question.

6. Originally Posted by 110.14(D)
That's my user name, not a question.

Hahaha you got me-- didn't catch that

7. Originally Posted by 110.14(D)
Preparing to take a Master Electrician Exam, just looking for some help along the way. I'll be posting questions as needed to get through the course, currently in Unit 6 - Conductor Sizing and Protection Calculations.

We are anxiously waiting

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## Feeder Sizing @ 90°C

Page 249 Figure 6-16

If 300A continuous load @ 100% with 90°C wire on 90°C terminals is permitted, using the 90°C column for XHHW wire the first conductor size over 300A is 300kcmil at 320A. Why is the answer for this example 400 kcmil @380A? I thought I understood this concept in the 2017 NEC Handbook Section 215.2, but I can't get the right answers in any of the examples in the Exam Prep Book.

What am I missing?

9. 300 x 125%= 380

The question seems to imply that the breaker is rated 100% but if that is not the case then 400 kcm is correct. The wording, to me, is a bit off.

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I failed to mention the 400A breaker.

The point of the example seems to be that 90° wire can be used at full 90° ampacity on 90° terminals permitting a smaller size for that segment. 125% full load doesn't apply to that 90° segment, but I completely missed that 300 kcmil XHHW (320A @ 90°C) would be enough for the load but undersized for the breaker.
Last edited by 110.14(D); 04-02-18 at 05:58 PM.

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