Thomas & Betts XD7-TB 2 1/2 INCH EXP/DEFL COUPOLING

The XD7-TB is the 2-1/2 inch size in the Thomas & Betts XD expansion/deflection coupling family. One coupling handles one run of 2-1/2 inch conduit, so size the fitting to the conduit trade size, not to the box or enclosure it terminates at.

An expansion fitting takes movement along the length of the run only. The XD style, which is what the XD7-TB is, handles expansion AND deflection, meaning the conduit can also move side to side or angularly at the joint. That is why it gets used at building separations, seismic joints, and bridge or parking-deck joints where the two structures move in more than one direction. If your run only grows and shrinks with temperature in a straight line, a plain expansion fitting covers it; if the two ends can shift relative to each other, you want the deflection type.

Ductile cast iron. That is a structural-grade body rather than a sheet-metal or die-cast one, which is what lets it carry the conduit load across a building joint. For an electrician spec'ing this on a drawing, the material callout is ductile iron, 2-1/2 inch trade size.

Plan on it. An expansion/deflection coupling is a movable joint, so the metallic conduit path across it is not a reliable equipment grounding path on its own. Standard practice on deflection fittings is an external bonding jumper sized to the circuit, or an equipment grounding conductor carried through the raceway. Budget the jumper and its clamps on the material list when you order the coupling.

No. The XD7-TB is a ductile cast iron fitting built for rigid metal conduit runs. PVC systems use their own plastic expansion couplings with solvent-weld sockets. Match the coupling to the raceway material, not just the trade size.