Discussion in 'General Electronics Chat' started by Steve1992, May 1, 2010.
Is there a formula to calculate the current handling capacity for wire?
Eg. 26 AWG/1x0.4mm
There are no real formula's as far as I know.
You will find some tables on the internet.
Here is an example at the engeneering toolbox:
Different tables put different weights on the variables of voltage drop and heat production. Here is another source: http://www.pupman.com/listarchives/1998/April/msg00222.html
Note the comment about heat sinking increasing the current capacity.
For any given copper size, it also depends on the insulation type, how many wires are bundled together, whether they are in open air / conduit / buried, ambient temperature etc.
Here's a spreadsheet that you can use -- you'll have to decide how appropriate its predictions are for you. The details are given on the Ampacity tab. It's an Open Office spreadsheet, so you'll have to install Open Office if you want to use it.
I attached it as a PDF to give you an idea of its contents; however, the pagination is messed up and things don't get presented in logical order.
The conservative answer is 700 circular mils per ampere. See the following for additional information
Belden's cable basics