[TowerTalk] Entry Panel in Wall or External to Building?

[doc]

 From a thread on a different topic I viewed this picture
http://www.dutson.net/Ham/P6060006.jpg   and it prompted
a question.

It is best to mount the Polyphaser/ICE/whatever lightning
protection panel in the wall or window of the building
or in a panel/box that stands apart from the building?

I have been planning a box on a steel post a few feet from
the outer wall and to then feed the cables through a length
of 4" pvc into the radio room.

What is the greater risk?

1.  The discharge through the multiple Polyphasers to
ground when mounted in the wall or window bringing a
heavy charge into the shell of the building?  (Note:
in my case the building is steel.)

2.  Energy reentering the cables between a freestanding
grounding panel between it and the house?  (Note:  Does
the fact that my building is steel represent a mitigating
factor, tending to siphon-off energy to ground.)

Thanks! & 73, doc kd4e