... a structural expansion fitting.
Exactly what do you mean by this terminology... :?
I do not recommend LFMC or LFNC to allow for expansion. Neither is designed for such, and depending on the amount of expansion/contraction, may fail... usually at the connectors. Putting a curl in the run would help prevent failure, but make pulling slightly to substantially harder and also look bad... and then you have the bonding issue.
Worked for a contractor once that used LFMC instead of expansion fittings for a long pull of parallel 3?15kV cable in 4" GRC. IIRC about 1300' wire length, at least 800' in conduit which had say 4-5 "expansion joints" and a midway soap box, the balance in cable tray. The conduit was on the uphill end (it was on a coal conveyor at a power plant) so all the cable was to be pulled through the conduit section. It was a pulling nightmare, not to mention the final cost. A few of the EJ's also provided offset and the cable hung up on the internal metallic flex a little to begin with, then it kept bunching up the wraps internally as the pull proceeded, cable hung up more, and the dual tuggers let their smoke out.
On the correct way to install such runs, IIRC from another installation [different contractor/project], there may be expansion fittings which are listed as providing suitable grounding. They have an internal wire brush in the fitting barrel, which maintains the grounding when the joint moves.
