Section 300.7(B) Expansion, Expansion-Deflection and Deflection Fittings
(B) Expansion, Expansion-Deflection, and Deflection Fittings. Raceways shall be provided with expansion, expansion-deflection, or deflection fittings where necessary to compensate for thermal expansion, deflection, and contraction.
Analysis of the Change
A standard expansion fitting works when the raceways is installed in a straight axial alignment whereas the expansion/deflection fitting accommodates for the raceway’s thermal expansion or contraction when the raceways are off-set or misaligned. Raceways are installed in an imperfect world and can be exposed to angular deflection due to the structure in which the raceway is mounted to. Expansion-deflection fittings can compensate for the angular deflection and thermal expansion and contraction of the raceway. The use of expansion-deflection fittings will prevent damage and separation of the raceway and maintain both mechanical and electrical continuity. The revised text makes it clear to inspectors, designers, and contactors that expansion-deflection and deflection fittings are acceptable to be used with raceways to address thermal expansion, deflection, and contraction.
Products
T&B Metal Expansion Fitting and Metal and Nonmetallic Expansion-Deflection Fittings and Carlon Nonmetallic Expansion Fitting
