Voltage Drop

[Dave123]

As far as code is concerned, if you are running two different size conductors (e.g., 12awg and 6awg) to meet voltage drop requirements, does it matter where the larger wire is placed.

[neil seidner]

I checked the references on table D-3 and could not find any requirement. Usually the larger conductor is on the home-run conductor, but this is probably just because it is the longest conductor, or (in the case of a circuit supplying several outlets) the conductor carrying the most current. Basically the cheapest way (in terms of labor and materials) to obtain less than 3% voltage drop.

[Cosimo Diano]

Voltage drop is based on load.
Let us know what your doing and we can help to lay it out for you.

[Cosimo Diano]

8-102 Voltage Drop shall not exceed 5% from the supply side of the consumers service to the point of utilization and not exceed 3% in a feeder oor branch circuit. So if the service has a 3% voltage drop the branch circuit cannot exceed 2%.

[Cosimo Diano]

<font color="#a62a2a" size="1">[ May 10, 2004 11:49 PM: Message edited by: Cosimo Diano ]</font>

[Dave123]

The question came up at work the other day with respect to outside pole lighting? "they only pulled #12 to the panel and it should have been #6." My reply was, as long as there?s no ampacity issue (which there wasn?t, #12 met the requirement), then run whatever size you need to meet the voltage drop requirement after the first pull box ? in this case #6 would keep the voltage drop within 3% for the branch circuit. His reply was? but I?ve always run the larger wire first, I think that the way it?s suppose to be.

Even though I?m only a 2nd year apprentice I felt confident explaining to him that in theory it really doesn?t matter where the larger wire is place. In fact, I explained that if for some reason we could only gain easy access to the middle 25% of the run and say a #3 wire would keep the voltage drop within requirements, then this would be fine? hope I was right.

As far as code was concerned I couldn?t recall anything but just wasn?t sure.

Thank you for the replies.