voltage drop

Status
Not open for further replies.
C

cmparsons1

Member
Can anyone Help explain to me why when using different reference books the value for " K " of copper wire changes from 10.4 to 18.1? Is this kinda a problem that allows you to re calc if your first attempt wasn't low enough?
 
Re: voltage drop

It sounds as though the books you are refering to are giving "Exact K factors". Generaly speaking it is the "Approximate K factor" that is used for quick calculations, this 12.9 for copper.

To find "Exact K factor" you can use this method.

R x CM / 1000 feet.

R = resistance
CM = circular mills

This will change with other variables, but this will get you close.

Roger
 
Re: voltage drop

The resistivity varies with temperature. The value at 20 degree K = 10.3 and 10.6 at 25 C.
As the temp increases K increases.

[ October 19, 2003, 05:52 PM: Message edited by: bob ]
 
Status
Not open for further replies.
Top