formula for proper wire length from 18 to 2 awg wire

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ozeke

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I would like to know if there is A formula for proper wire length, when running 18 down to 2 awg wire thru emt. I am running some 12 awg thin wall wire, thru 1/2" And 3/4" emt. I am running 3# 12 awg thru the 1/2" And I will be running 6# 12 awg thru the 3/4, the drop run is about 35'ft
And I will have A electrical box at 20'ft.
am I within code And how could I use A formula
for knowing the proper length of wire to run when using A lighter awg wire.
 
Re: formula for proper wire length from 18 to 2 awg wire

Wire size is normally based on the ability of the wire to handle a certain amperage with out exceeding the temperature rating of the wire. Also you have to derate when running more than 3 current carrying conductors in a raceway. but I'm not sure what your asking as to length as there is no restrictions on how long a circuit conductor can be other than voltage drop? but If you are trying to figure for voltage drop go here:
ElectricalFormulas.pdf
 
Re: formula for proper wire length from 18 to 2 awg wire

Along with Wayne's good info I would say if you are taking about line voltage / branch circuit wiring you can forget about 18 & 16 AWG.

With few exceptions 14 AWG is the minimum size for 120 volt circuits.

All you told us was what size and how many conductors are in the raceways.

You will need to know the connected load and what type of equipment is being supplied.
 
Re: formula for proper wire length from 18 to 2 awg wire

There are no limits to the length you can run conductors per NEC. You can increase the size of conductors to compensate for voltage drop beyond what the NEC calls for in 310.16, but it is not required, that is a design issue.

As mentioned if you run more than 3-current carrying conductors in a raceway, you will also have increase the size per 310.15 to compensate for the added heat.

Clarify what it is you want to know.
 
Re: formula for proper wire length from 18 to 2 awg wire

Thank you very much hurk, iwire And dereck for the info. Ozeke"
 
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