I have a 6/3 NM-B cable that is to be run through a Southwire Ultratite conduit to an external outlet for a generator. I plan to strip the cable prior to threading through the conduit: 1. for ease of passage; 2. for thermal issues. Just wondering what is the protocol for where the stripped section should start - just outside the conduit, or just inside? Also, the Ultratite fitting at the back of the outlet box has no provisions for clamping the wires in place. Can I presume then, that in this instance, clamping is not necessary as long as the wire is firmly anchored before entering the conduit run?
There are (at least) two problems with this, and the solution to both is to change to THWN (or another wet-rated labeled conductor) when you change to conduit.
Problem one is that stripped NM is not labeled and not acceptable per code for that reason, as @Speedy Petey said.
The second is that you are running to an external location, which means that the conduit is by code defined to be a wet environment, and even with the sheath on, NM is not rated for wet locations, but you need a wire that is rated for wet locations.
i am assuming this is a USA install. once you remove the cable sheath you install it just like single wires if they are properly rated (at least as high as your peak voltage, usually 300 or 600 volts). there is no need to leave parts of the sheath on. if these wires are not rated or are not sufficient then you need to use real THHN singles or install it with the sheath all the way. i am not familiar with the type of conduit you mention. the uninsulated ground wire in metal conduit could be an issue (it can spread fault current to the conduit). you could buy a spool of green insulation THHN to replace any uninsulated ground wire with.