[TowerTalk] Question about ground

[Matt Fearnow]

Hey all I'm relatively new. I'm running a ground for my ground rounds for antenna coax junction.  I have to go from my electrical service panel ground rod about 80'. 

2 questions
1) how deep should trenching be?
2) does brick dust used as a natural stone mulch, will that affect the ground wire?  Some areas it is only 1-3" others it seems to be 4-5" deep of brick stone. 

Thank you in advance for guidance. 

Matt Fearnow
73 - Matt - W9SIG