If you were to use two different gauge sizes of cable per phase of a three phase electricity installation would the smaller gauge cable get hotter?

This seems like a question from an electrical course, and is probably best answered by referring to your course materials.

It's your test question, not ours, and there won't always be someone else to ask for the answer.

Earn your diploma.

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By asking this question here, was what you expected that someone might just do all the hard work of looking-up the information... to write an answer for you to copy...?

If that is right, you may or may not get lucky here!

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Yes, it would get hotter, and that is exactly why it isn't allowed in the NEC.

The NEC specifies that all conductors used in parallel insulations shall be of the same size and of the same insulation rating.

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Actually the answer is no, the smaller gauge wire would not get hotter than the large one assuming both are same composition (copper). This is due to the higher resistance of the smaller wire which allows less current to flow for a given voltage drop. The larger gauge wire will carry more current due to it's lower resistance. In this instance current in the wire is inversely proportional to it's resistance. However as has been stated previously this practice is unsafe and prohibited by the national electrical code (NEC).

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A Watt is a Watt is a Watt.

If the load draws 40 amperes, then it will draw 40 amperes regardless of the wire size. If your wire size is not matched, and the load is too high for that wire size, then yes, it will get warmer. This is one way that fires are started.

First answer by ID0000000000. Last edit by Paradoxicon. Contributor trust: 0 [recommend contributor]. Question popularity: 146 [recommend question]