I have tried to find it in the code ,can't find it. how many threads need to be engaged in to a myers hub ,LB,ect. we got some conduit RMC in and we basicly have to rethraed it if we use any thing other than the coupler that comes on 1 end.

Don't quote me on this, but if memory serves, it is a minimum of 3 threads.

The only thread engagement requirement I can think of is in classified locations, which require 5 threads, or under the 2005, 4.5 or 5 threads, depending on listings.

I'd check UL's website, they would be more interested in the detailed installation of materials than the code book.

www.ul.com