I'm wondering does anyone know the surge impedance for buried copper cable? I need the derived formula also.

 

I have never heard of any such rating or calculation for any type of wire.

I do know that if the implied or surge voltage and current is high enough your cable will no longer exist.

You can do some searches on copper wire specifications, check out the NEC or UL website, try
http://www.mikeholt.com

or, look up resitance data or copper wire, do some brainwork and figure it out for yourself.

MJH

 

Surge impedance is the characteristic impedance of a transmission line. It is resistive for a properly terminated transmission line and exceedingly complex for anything else. If you have a properly shielded cable it's surge impedance should be the same buried as aboveground.
Unless it's coaxial, it's likely a balanced (twisted pair) transmission line where each pair in the cable is a transmission line. And if it is a controlled impedance cable, it's characteristic impedance should be specified. Surge impedance takes into account that an unterminated line will exhibit it's characteristic impedance until reflections occur. That time is related to the length of the cable and it's propagation velocity.

Regards

cww

 

Responding to Kevin's query... Which of the four "Surges" that come to mind are you interested in:

1) Surge Impedance as related to transmission line characteristics.

2) Surge Impednce as related to loading of a transmission line.

3) Surge or asymmetrical or crest factor for short circuit currents.

4) Surge Impedance as related to traveling wave theory related electrical overvoltage transients.

Regards,
Phil Corso, PE {Boca Raton, FL, USA}
[[email protected]] ([email protected]) {[email protected]}

 

It would be lighting applied and that would be number 4.