[TowerTalk] ground systems... ferrous conduit

[Jim Brown]

On Wed, 2 Feb 2005 18:33:28 -0500, Tom Rauch wrote:

>I don't understand that.

I don't either. Some clarifications. 

I am QUITE certain that any smart engineer would specify that the 
ground conductor be bonded to ferrous conduit at each end. Why?  
Because it it was not bonded, the conduit WOULD significantly 
increase the inductance of the ground wire running through it. But 
by bonding it at both ends, the bonding conductor consists of the 
parallel combination of the copper wire inside it and the conduit 
itself. At low frequencies, the copper may contribute significantly 
to the conductance. As frequency increases, the current will flow 
almost entirely in the conduit. 

On the other hand, ferrous conduit that is buried would need some 
sort of serious protective coating to prevent it from degrading over 
time. Many folks recommend the use of PVC for conduit that will be  
buried. 


Jim Brown  K9YC