Have a job that requires "swapping" of circuits from one panel to another. Past experience tells me that one must remove said circuits entirely from panel enclosure as it is not permissible to use a panel or disconnect enclosure as a raceway for other systems. I got to looking at 300.3 4C and 312.8 and it would seem to cover panel board enclosures so long as sufficient space exists for wire fill. Thoughts?

Guess its a good thing this didn’t come up on anyone’s Journeyman’s test.

408.2 says 312 applys so I;d say yer right . Long as space is there.

Just be aware a lot of AHJs take the first part of that sentence seriously "Enclosures for switches or overcurrent devices shall not be used as junction boxes" and they may want you to show that the listing for that enclosure and panelboard did provide "adequate space for this purpose".

You can't just take the first part of a sentence and ignore the rest.

You are allowed to use a panel as a jbox provided you meet the rest of 312.8 and unless you are really loading up the panel with splices or it is an older smaller panel there should be plenty of room.

Scott, If I was looking at this and it was done in such a way that did not clutter up the panel too bad I wouldn't have a problem with it but I know some guys who dissagree and have a very limited interpretation of what 312.8 allows.
I have even heard more restrictive spins on this in IAEI seminars from respected road warriors.