audioaddict
Active member
I have some extra time today and decided to compare all the various voltage drop methods (there are a few)...both single & 3 phase problems.
Methods are Ugly's handbook, Bussmann chart, and of course the PE NCEES method using Chapter 9, Table 9. I wanted to see if there were differences...and the results were interesting.
Here's what I came up with:
Problem #1
Single Phase, 240 Volt, #8 THWN, 30 amperes, 150 feet
Ugly's 2008 handbook:
Vd = (2 x K [copper constant] x L (distance) x I ) / circular mills
= (2 x 12.9 x 50 x 3)/16,510
= 7.03 volts
Bussmann: 150 feet x 30 amperes = 4500
4500 x 1520 [100% pf, single phase for #8 wire] = 6,840,000
Divide by 10^6: 6.84 volts
PE method: Z = (.78 + j.065) * ((150 * 2)/1000)
= .234 + j.0195
I * Z = 30 (.234 + j.0195)
= 7.04 volts
So far so good...all 3 yielding similar results.
3 phase is next and this is where the fun begins.
Methods are Ugly's handbook, Bussmann chart, and of course the PE NCEES method using Chapter 9, Table 9. I wanted to see if there were differences...and the results were interesting.
Here's what I came up with:
Problem #1
Single Phase, 240 Volt, #8 THWN, 30 amperes, 150 feet
Ugly's 2008 handbook:
Vd = (2 x K [copper constant] x L (distance) x I ) / circular mills
= (2 x 12.9 x 50 x 3)/16,510
= 7.03 volts
Bussmann: 150 feet x 30 amperes = 4500
4500 x 1520 [100% pf, single phase for #8 wire] = 6,840,000
Divide by 10^6: 6.84 volts
PE method: Z = (.78 + j.065) * ((150 * 2)/1000)
= .234 + j.0195
I * Z = 30 (.234 + j.0195)
= 7.04 volts
So far so good...all 3 yielding similar results.
3 phase is next and this is where the fun begins.