And also seen 1/2 FMC fittings used for 3/4 EMT. Works great when you ran 3/4 but didn't know how to enlarge a 1/2 KO, or if you needed a 90 degree connector:blink:Agree, if set screws are tight then your are good to go, but Ive come across installations [done by others] with duck tape used for couplings.hmy:
Oh, you're quackers!
(yes, I know about that brand)
What did you say????
If rusting from inside out was not arranged to drain.
Used to be it was used in concrete... now pvc conduit more common. But, emt is still allowed in concrete as I recall.
PVC preferred in slab on grade or in walls below grade. Above grade I don't think matters much most cases unless corrosive agents are involved in the general area.
In rooftop applications it is specified to overcome the possibility; some would say likelihood; that the connections of the steel EMT will corrode open.If the raceway is so good as an EGC why is there ever a need for redundant grounding? Needs to be extra good?
Because it's cheaper. Why Else? They specify compression couplings but many of those are not evan listed as rain-tight. And then for good measure they specify aluminum boxes to throw dissimilar metals into the mix. I've actually have seen one aluminum EMT job with all compatible fittings and boxes but that was on the roof of a a Biotechnology Laboratory.
Design decision, not a code requirement. Just as much design decision as one could run stainless or brass conduit and probably have little or no corrosion troubles, but would definitely be more expensive.
