[TowerTalk] Lightning Arrestor Question

[Jerry]

I have a box at the base of my tower housing my DX Eng. antenna switch 
box that also provides a central entry point for all the antenna cables 
(prior to going underground to the house).  Will placing an arrestor 
only on the output coax from the antenna switch to the house be 
sufficient or do I need to place an arrestor on each antenna line 
entering the box and switch (the shields are all grounded to the ground 
system in this box)?  Additionally, do I need to place an arrestor at 
the house's central grounding point (where it enters the shack)?  
Overkill?  The grounding system is all tied together (tower, switch box, 
house entry point, and home's electrical system). 
Thanks for any help/ideas you can give me.
Jerry France
K7LY
Lake Havasu City, AZ