voltage drop multipule conductors

[ohmhead]

Well question i have a 1200 amp /480 volts /3 phase / length 600 feet /aluminum / pvc /emt raceway one way underground and over head raceway to a swbd i need a voltage drop calculation this is just a basic question no engineering programs or input needed.

I see paralleled feeders just for sake say 4 runs do you calculate each conductor meaning divide up the voltage drop or use the total resistance of the combined conductors by the number of them in the raceway .

Give me a example of the simplest formula i see page 49 in the Uglys book and they are multiply feet x amperes then divide permissible volts loss by 1000000 and divide this by 7200 .

What is 7200 ?

Why or how does this example work please explain if you can .

Could i just divide up voltage drop per conductor in the run and use just the current of one conductor for this .

This is just for my benefit to understand better .

 

[charlie b]

Parallel conductors work the same as parallel resistors. Presuming they are all the same size (as they are required to be), the total resistance of a set of four conductors in parallel will be one fourth the resistance of any one by itself. Therefore, the voltage drop across a set of four parallel conductors will be one fourth the VD across one alone. So calculate the VD as though you used only one conductor, and divide the answer by four.

By the way, my copy of Ugly's (2008 edition) has VD calculation examples starting on page 52, not 49, and the number 7200 does not appear. So I can't answer that part of your question.

 

[ohmhead]

Thank you Charlie B thats what i needed to know my Uglys is a 1999 edition so what can i say .

I will try one conductor and divide the voltage drop by the number of conductors on same phase .

Were just interested in knowing how this is done with more than one run .

Take care :thumbsup: