What type of fittings should be used in raceways for accommodating movement caused by temperature changes?

The correct choice is expansion fittings. These fittings are specifically designed to accommodate the movement that occurs in raceways due to temperature fluctuations. When temperatures rise, materials tend to expand, and when temperatures drop, they contract. Expansion fittings allow for this movement without putting stress on the connecting components or the raceway itself, thus preventing potential damage or failure of the electrical systems housed within.

In contrast, contraction fittings address scenarios where materials are compressing, which is less common in raceways that must accommodate expansion. Deflection fittings may allow for some bending and are typically used in structural contexts rather than for temperature changes. Support fittings focus on securing and stable positioning rather than accommodating movement due to thermal expansion or contraction. Therefore, expansion fittings are the most suitable choice for ensuring the proper functionality and longevity of raceways in environments subject to temperature variations.