Slick and/or approved install methods of LB on corrugated steel bld?

[fastline]

I've read conflicting info on drilling the backside of an LB for screws, but regardless of code, they need to be secure! Sometimes I try to bush then in place from the inside, but I typically use Butyl rubber for a long life seal and it needs good compressor to do the thing.

Corrugated steel is always a challenge. No flat surface to work with, and if you are drilling holes, you are only going into sheet metal most of the time....I guess unless you install threadserts or something.

 

[Rick 0920]

I use Unistrut and span the ribs with a 10"-12" piece. You can put a 2x4 on the inside for support of the strut. Now your conduit can be secured with a strut strap and a short nipple used to get in the building.

 

[petersonra]

If you have access to the back side of the steel why not just use a self tapping screw from the outside and then use a sealing washer and nut on the inside to hold it in place. Just use standard straps that way.

 

[Rick 0920]

If you have access to the back side of the steel why not just use a self tapping screw from the outside and then use a sealing washer and nut on the inside to hold it in place. Just use standard straps that way.

The beauty of our trade is that there are multiple ways to accomplish a task and every one of them can be correct!