Contractor Exam Prep - Unit 9 Challange question 34

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S-117

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florida
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This problem mentions that the load demand is 30,000 VA on an 120/240 V service

I have two questions.

1) why is the large voltage used to obtain a smaller amperage? This would be less conservative, no?

2) why is 75degree assumed in most problems when using table 310.15(B)(16) ?
 

david luchini

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using smaller wire size is not less conservative?

please explain

The load will be connected to both legs of the 120/240V service. There is 240V between those two legs. The 30,000VA load will be 125Amps.

Using 250A of wire would be more conservative, it would be more wasteful.
 
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