Interesting topic… Out of habit, I use primer on all the NM pipe and conduit fittings I install, whether it’s for pressure or just electrical wiring. I’ve never seen where primer was required, but I also don’t really see where it’s not allowed.
There’s no doubt in my mind that it makes for a much stronger faster setting, joints that are impervious to water seepage. Granted with conduit, you may still get condensation accumulation inside, but at least there won’t be additional water leaking in from the joints themselves.
Unless you actually saw me using it though, you probably would never know I had, since I normally use the Rectorseal PR-3 clear PVC/CPVC primer.
As far as the Carlfex being cemented directly in FS box fittings, I’ve seen that done on dock wiring before and I would agree that is the strongest, most durable and watertight connection that can be made. It looks like it would make for much easier wire pulls as well.
I’ll bet the only reason Carlon doesn’t get its Carflex UL listed for installation that way is because they would lose all that money they make for their required crappy Carflex connectors.
