The two lights shown in the photo were fed from a junction box that was destroyed when a truck backed into it. I'm thinking of running new conduit above vehicle level, and the most straightforward way would be if I could daisy-chain the lights, i.e. have power enter from a conduit to the right of the right-hand light, use that light as a junction box, with another conduit coming out the left side to feed the other light. My question is: is there any restriction in code against using the light fixture as a junction box this way? Thanks!
Since this is all on the same circuit, you can do this as it falls under 410.64(C):
(C) Luminaires Connected Together. Luminaires designed for end-to-end connection to form a continuous assembly, or luminaires connected together by recognized wiring methods, shall be permitted to contain the conductors of a 2-wire branch circuit, or one multiwire branch circuit, supplying the connected luminaires and shall not be required to be listed as a raceway. One additional 2-wire branch circuit separately supplying one or more of the connected luminaires shall also be permitted.
See also 410.21 and the note thereto:
410.21 Temperature Limit of Conductors in Outlet Boxes. Luminaires shall be of such construction or installed so that the conductors in outlet boxes shall not be subjected to temperatures greater than that for which the conductors are rated.
Branch-circuit wiring, other than 2-wire or multiwire branch circuits supplying power to luminaires connected together, shall not be passed through an outlet box that is an integral part of a luminaire unless the luminaire is identified for through-wiring.
Informational Note: See 410.64(C) for wiring supplying power to luminaires connected together.