2002NEC 210.19

I just happen to have two (DSL) movies on this at

think you get the same answer if you use Table 8 values with Ohm's Law or use the formula with K=12.9. I learned this as VD = 2*K*L*I / CMA x ( a multiplier of .866 for 3 -phase 3- wire or times .5 for 3-phase 4-wire.) Where K = 11.5 to 12.9 depending on the operating temperature of the conductor. L is one way circuit length in feet I is amperes CMA is circular mil area of the conductor from Table 8 Chapter 9 of the NEC.

My advanced voltage drop calculator at electrician.com approximates the conductor operating temperature using estimates of RCA derived from Table

310.16 using the 75 degree C. columns. I worked on this method for about 8 years on and off before I realized that the conductor temperature could be estimated using a calculation. An explanation of this is given at: And, of course, the entire problem assumes a power factor near 1.0, a sinusoidal waveform, and a frequency near 60 hertz. Extremely low power factors, other wave shapes, and very high frequencies require other factors solved by electrical engineering math. (We must always know our limitations, we electricians are not engineers.) A good general nontechnical explanation of these factors can be found at the volume on AC Circuits.

Now on the Exam, I have had the same problem. I always ask which do you want and which value of K do they want. Usually, the test administrator or proctor doesn't have a clue. Good luck.

The proctor does not answer questions! They even state this "twice" before each test.

I just happen to have two (DSL) movies on this at

think you get the same answer if you use Table 8 values with Ohm's Law or use the formula with K=12.9. I learned this as VD = 2*K*L*I / CMA x ( a multiplier of .866 for 3 -phase 3- wire or times .5 for 3-phase 4-wire.) Where K = 11.5 to 12.9 depending on the operating temperature of the conductor. L is one way circuit length in feet I is amperes CMA is circular mil area of the conductor from Table 8 Chapter 9 of the NEC.

My advanced voltage drop calculator at electrician.com approximates the conductor operating temperature using estimates of RCA derived from Table

310.16 using the 75 degree C. columns. I worked on this method for about 8 years on and off before I realized that the conductor temperature could be estimated using a calculation. An explanation of this is given at: And, of course, the entire problem assumes a power factor near 1.0, a sinusoidal waveform, and a frequency near 60 hertz. Extremely low power factors, other wave shapes, and very high frequencies require other factors solved by electrical engineering math. (We must always know our limitations, we electricians are not engineers.) A good general nontechnical explanation of these factors can be found at the volume on AC Circuits.

Now on the Exam, I have had the same problem. I always ask which do you want and which value of K do they want. Usually, the test administrator or proctor doesn't have a clue. Good luck.

| I just happen to have two (DSL) movies on this at

Can anyone here convert these two DSL movies for me to T1 format? I'd like to download them, but my Linux computer is on a T1 circuit, not DSL.

:-)

Okay, it took a second, but now I get it :-)

LOL daestrom

I'm sorry, but all we have available is the low bandwidth version. We are currently looking into emulating slow, jumpy video feeds into our high bandwidth products to give all users the same web experience.

;-)

I think you get the same answer if you use Table 8 values with Ohm's Law or

I did an Excel plot of VD vs D using the Voltage drop formula (VDF) as one series and Ohm's Law (OL) as another series. It's easy to see then how OL will result in undersized cables as distance increases. For example, 250 kcmil, 350A, 480V. Max voltage drop of 14.4V is around 450 ft. using VDF, and OL says your still under at 775 ft. I'll have to print it a take it to class. Thanks. Chuck