What type of fitting must be used where a raceway crosses a structural joint intended for expansions, contraction or deflection in buildings?

The correct choice involves using an expansion/deflection fitting in situations where a raceway crosses a structural joint that is designed for movement due to expansion, contraction, or deflection within a building. This type of fitting is specifically engineered to accommodate the shifts in alignment and size that can occur as temperatures change or as the building settles.

Using an expansion/deflection fitting allows for the necessary flexibility in the wiring system, helping to maintain the integrity of the electrical installation and preventing damage to the raceways or the electrical conductors within them. It ensures continuous electrical paths while addressing the mechanical stresses that arise from movement in the structural joints.

This choice distinguishes itself from others since junction boxes, structural joints, and cable trays do not serve the same purpose in accommodating movement. A junction box is intended for connecting conductors and does not provide for flexibility. While structural joints refer to the physical spaces where movement is expected, they do not incorporate any mechanism to manage change in the raceways themselves. Similarly, a cable tray serves a different function in providing support for cables but does not allow for the necessary movement at structural joints.