Solving for Length in a calculation (Sorry if this is misposted. I'm green here.

[scout117]

I have 12 AWG copper wire. How many ft would be required to produce 5 Ohms of resistance?

Typically, I'd calculate Ohms/mil-ft (10.4) by 1000' and divide by the circular mils (CM) to reach a conclusion of 1.59 Ohms for 1000' of 12 AWG wire.

My question what formula would I use to calculate how many feet of wire to produce 5 Ohms of resistance?

 

[gar]

180722-1534 EDT

If you know the resistance for for some number of feet of wire, then divide that value of resistance into the desired resistance. The resulting number is then multiplied by the said number of feet.

Your example:
5/1.59 = 3.14
then
3.14 * 1000 = 3140 feet

.

 

[ggunn]

I have 12 AWG copper wire. How many ft would be required to produce 5 Ohms of resistance?

Typically, I'd calculate Ohms/mil-ft (10.4) by 1000' and divide by the circular mils (CM) to reach a conclusion of 1.59 Ohms for 1000' of 12 AWG wire.

My question what formula would I use to calculate how many feet of wire to produce 5 Ohms of resistance?

Go to Table 9 (assuming AC). AWG #12 is 2.0 ohms per 1000'.

2.0 ohms/1000' = 5.0 ohms/x, solve for x.

x =2500'

 

[Carultch]

I have 12 AWG copper wire. How many ft would be required to produce 5 Ohms of resistance?

Typically, I'd calculate Ohms/mil-ft (10.4) by 1000' and divide by the circular mils (CM) to reach a conclusion of 1.59 Ohms for 1000' of 12 AWG wire.

My question what formula would I use to calculate how many feet of wire to produce 5 Ohms of resistance?

You are getting conflicting answers, because the resistivity of copper is a function of temperature. The 1.59 Ohms/kft is a realistic value for room temperature (possibly 20C), and the value closer to 2 Ohms/kft is a value for 75C operating temperature. The calculation process is still the same, the data for unit resistance is slightly different.

If you are measuring ohms of a non-energized circuit, the 20C value is more realistic.