Resistance questions are fair game on the exam. Can you answer the following question?
Question:
What is the resistance for 200 feet of #6 stranded coated conductor installed in an ambient temperature of 90 degrees C.?
To arrive at the correct answer you’ll need to know:
Is the wire type used copper or aluminum?
What does the reference to “stranded coated conductor” mean?
Where can the resistance value for #6 stranded coated conductor be found in NFPA 70?
Does an adjustment factor for ambient temperature need to be applied, if so what is it?
Does the length of the conductor affect resistance, if so how should it be adjusted?
Solution:
.491 ohms x 1.05 = .516 ohms
.516 ohms x (200 ft. /1000 ft.) = .103 ohms final answer.
This question well illustrates why if you want to prepare to pass your exam you need to do more than just memorize random questions that you may or may not see on your exam. You need a foundation of knowledge that will allow you to correctly apply the code to any exam question.
We have over 30 years experience helping electricians navigate their way to a passing score on electrical examinations. Preparation is the key to success! Our patient and knowledgeable instructors can help you understand and apply the code and calculations you’ll need to know to pass your exam.
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