[TowerTalk] Re: Floating Ground Steel Building?

[Jim Lux]

At 02:42 PM 7/2/2004 -0400, doc wrote:
>I just left a meeting with the builder of our new steel home
>where I discovered something troubling -- the steel roof and
>wall materials appear to be floating above ground on top of
>the concrete slab!
>
>The roof and wall are 10" x 48" wide sections bonded together
>and along the bottom of the wall set into a metal channel
>fastened to the concrete with embedded anchor bolts -- but
>those bolts are buried in the slab, none of them are grounded.


The slab itself is grounded, isn't it... This is what UFER ground depend 
on. There may be a moisture barrier between the slab and some of the 
ground, but the footings around the edges should be in contact with the 
soil, and there's a fairly large contact area there.



>So when I bring everything to the entry panel the only point
>of ground is the three planned 20' rods -- for the entire
>steel house shell as well as for the power line, phone,
>tower-related cables, and well cables.
>
>I have been counting on the steel shell wicking off lightning
>energy through multiple grounding points minimizing the collection
>of energy at any single point.
>
>Should I place ground rods at the corners, and perhaps at
>additional 10 or 20 foot locations around the perimeter of the
>60 x 40 structure, and tie them to the base plate of the
>outer metal wall?


What's the contact area of a wire or rod compared with all those square 
feet of concrete?




>The lightning storm that just rolled through reminded me to take seriously!