[tenday]

You assumptions are correct - Don’t I need a wire clamp to hold Romex in junction box ? If I do, how the heck is that done as the wire clamp threads on back of junction box?

 

[tenday]

 

[tenday]

Do you have a name for this ? Is it this ?

 

[tenday]

That's it and it's called by a few names.........
Cable connector (with size given, 1/2", 3/4", etc.)
Romex connector
NM connector

Problem is - when a cable connector is on the back of junction , the clamp sticks out the back by about 3/4"!

 

[tenday]

May have to drill a 3/4 inch relief holes about 1 inch into the house to make room for the clamp …. Ugly solution.