250MCM for 21.7 amps? Voltage drop calc must be wrong?

[Sahib]

Very insightful question!

 

[Ultrafault]

Your voltage drop calculator is wrong. Most of the calculators you can download are wrong when calculating phase to neutral loads. They incorrectly double the distance from the source to the load when calculating phase to neutral voltage drops. The definition of voltage drop is the drop from the source to the load, not the drop from the source to the load and then back again to the source. If you have access to an Eaton Consulting Application Guide, run your voltage drop calculation using their published voltage drop tables and you'll find you can do your circuit with #1/0 at 90% power factor. Then do it again with double the length of the circuit and it requires #250 kcmil just like the downloadable calculators show. Unfortunately, these calculators are prevalent and many engineers and electricians are putting in conductors much larger than required for phase to neutral single phase circuits.

Stephen W. Nelson, PE, RCDD
Leo A Daly

The added resistance back to the source still exists. If a person used your method the actual voltage drop would be more than your calculated voltage drop.

 

[GoldDigger]

The added resistance back to the source still exists. If a person used your method the actual voltage drop would be more than your calculated voltage drop.

:thumbsup:
And the Eaton guide is either wrong or is assuming that there will be roughly balanced loads sharing the same neutral.
If the ungrounded line voltage does not drop at all but the neutral voltage rises the load will still indisputably experience a voltage drop.
The semantic games with "source voltage drop" are just games and do not serve any real world purpose.

 

[topgone]

Are you saying a voltage regulator is for regulating voltage

Wrong.
He is saying that the price one pays for a regulator will be a lot cheaper than sizing the wires correctly.:lol:

 

[Sahib]

He is saying that the price one pays for a regulator will be a lot cheaper than sizing the wires correctly.:lol:

The price one pays for a regulator may be a lot cheaper than sizing the wires correctly for the voltage drop.:dunce: