A comment on an answer to this question seems to be saying that its illegal for an unswitched hot to run through a light fixture junction box, even though its not connected to the fixture at that point. (The light fixture would be receiving switched hot on a taped-white return from a switch).
Is this true and if so, could anyone give a pointer to where I should look in the NEC for that? I'm planning a little electrical work in the near future and I'm not aware of this restriction.
I am aware of the 2011 NEC rule which specifies that neutral must now be available at the switch to allow for new electronic lighting controls, which I imagine in many cases could result in the installation being wired differently such that the unswitched hot and neutral run to the switch directly rather than via the fixture.
But I can't see why in an older installation that it would be illegal or dangerous for unswitched hot to be routed via the fixture junction box.
Best Answer
Clarification: I think that there was a miscommunication in the post that you are referencing. It would be illegal for a neutral wire to be shut off (disengaging a light or device by breaking the neutral conductor). brhans didn't mean the fixture was hot (breaking neutral). brhans was saying the hot passes through the BOX and goes to the switch, and CarlWitthoft was confused, saying that a hot wire connected to the fixture would be illegal (meaning the switch was breaking neutral).
It is legal for (hot) wires to pass through a junction box. NEC Chart 314.16.A says how many wires (sizes) are allowed in various (sized) boxes.