Approved methods for capping off R.I.P. conduit?
e.g. you have a metal j-box embedded in the exterior stucco/concrete, and several IMC/RIGID conduits coming into it from the sides, and even straight in the back, likewise embedded in concrete, and now one of those conduits (for a 3-way switch) is no longer needed. I'm familiar with the steel knockout plugs that snap into place, but in this case, the conduit isn't budging, and can't be separated from the box.
Does that empty conduit have to be "capped off", and if so, how? Seems like the unused conduit is now a theoretical fire path, with no offsetting advantage.
What say ye, RKIs?