calculating x and r for conductors

[necnotevenclose]

Please help! I've been given the task to provide short circuit calculations using x and r values for conductors. The problem is I've never done this for conductors. Could someone please tell me how to get x and r values for conductors (formula) and/or a link to a site that may explain.

Thanks!

 

[rr]

This is an excellent resource for Fault Current Analysis:

http://www.bussmann.com/library/docs/EPR_Booklet.pdf

And to get X and R values for conductors look at NEC Table 9. Also refer to Note #2 on this table as well.

 

[jtester]

If you are doing an accurate fault current calculation, you must determine the X and R values of the circuit, not just the conductors. The conductor spacing, relationship with ground, etc., are as important as the values of the wire itself in determining the proper impedances to use in fault current analysis.

Jim T

 

[kingpb]

I recommend that you sit down with the engineer of record, and ask for assitance. These calculations should be performed only under direct supervision of someone specifically trained in doing these types of calculations.

 

[coulter]

nnec -
Three good postings with good advice. The only thing I could add is: Rocket science it's not, tedious it is. You could take a good class and do a few by hand. If you don't have any peer group review available at work, invite your favorite instructor out to lunch. Only then get software for the rest.

carl