back to back box installation in the concrete wall in the light of IBC

Jin Kim

Member
Location
USA
Occupation
Electrical Engineer
Hello, fellows.

I have been dwelling on this matter, but still haven't got any documented guidelines.
the notorious "back to back box in the wall, that is considered as membrance penetrant per IBC".

Well... for the through penetration, IBC has a paragraph saying concrete wall as an exemption (714.4.1 of IBC 2021).

However, IBC is silence about membrance(back to back) in the concrete wall.
Of course, I can just seprate the boxes more than 2 feet, but it is so off putting and it won't work at the security doors where many of accessories are mounted on both sides of the wall.

My guts say having not less than the depth of concrete wall thickness between boxes should work, but... does any one have a good ground that illustrate what is should be like?

Any advice would be appreciated.
 
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