Hey I have a dumb question. If I have a 20A breaker and I need to upsize my conductors for voltage drop because its a long run, and I have say 50ft of #12 and 100ft of #10, do I need to install the #10 at the begining of the circuit at the breaker and the #12 at the end? Or is the voltage drop calculated based on the total length of wire and wire size and placement is irrelevant?
Voltage Drop/Wire Size
- Thread starter AK907
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- Chapel Hill, NC
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- Retired Electrical Contractor
I agree with roger but want to remind you of 250.122(B). The section with #10 needs a #10 egc.
LarryFine
Master Electrician Electric Contractor Richmond VA
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- Henrico County, VA
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- Electrical Contractor
AK, welcome to the forum! 
That's it, and, even though I understand it, if I'm running a couple of different-gauge extension cords, I still "must" plug in the heavier cord first, closer to the source. :roll:
The current in all parts of a series circuit is the same, until the NEC revokes the laws of physics.
And this is not so radical an idea. A state legislature decided that the value of PI was 'inconvenient' so it wanted to round the value to two or three digits and declare the new number to be the true value of PI.
This law somehow did not pass, but give it time.
Politicians and reality mix as well as oil and water.
lauraj
Senior Member
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- Portland, Oregon
Seems like you'd want the larger wire to cover the part of the circuit that is going to carry the most current, that would be the home run. Am I mistaken?
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- Massachusetts
I agree with you if it is a mulitoutlet circuit, I think most of us assumed a single load at the end of the run.
lauraj
Senior Member
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- Portland, Oregon
I agree with you if it is a mulitoutlet circuit, I think most of us assumed a single load at the end of the run.
Oh ok sure, I was assuming a multioutlet circuit for some reason.
Speedskater
Senior Member
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- Cleveland, Ohio
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- retired broadcast, audio and industrial R&D engineering
True if the circuit is going to be taped or split somewhere downstream, but by definition the current is the same at all points in a "series circuit".
Gustav Kirchhoff had quite a bit to say about this.
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petersonra
Senior Member
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- Northern illinois
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- engineer
Years ago an electrician explained to me why the neutral prong on a plug is bigger. It is because more current flows through that prong nowadays due to all the computers. They didn't use to need it before computers.
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- Massachusetts
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- Lockport, IL
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- Retired Electrical Engineer
That's the funniest thing I have heard in a long while. :grin:
LarryFine
Master Electrician Electric Contractor Richmond VA
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- Henrico County, VA
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- Electrical Contractor
"I don't think so, Tim!" :roll:
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