Conduit expanion fitting across expansion joints

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philly

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When running conduit what is typically used for allowing conduit to expand when running conduit across expansion joints or other areas that are open to expansion. In the past I've seen "flex conduit" used to allow for this expansion. I wanted to see what was typically used/specified in such expansion cases. Do others specify/use flex conduit or some other type of expansion fitting?

Particular application is a 2.5" RMC conduit across a structural expansion fitting.
 
philly said:
Thanks! Is the bonding jumper needed across the expansion fitting?
Click to expand...

I think so if you are using the conduit as ground.

Also they are made by a few companies with and without the jumper, I think they are expensive so you may want to shop them out if you have to get a lot.
 
iwire said:
I think so if you are using the conduit as ground.

Also they are made by a few companies with and without the jumper, I think they are expensive so you may want to shop them out if you have to get a lot.
Click to expand...

I am using an EGC so I guess I dont need the bonding jumper. I only have a few of these
 
I would use a piece of flex.

There is a flex with EMT on each end so you could just use EMT couplings and not have to use EMT conn-RGS coup-flex conn.
I can't remember who makes it though.
 
We use the XJ style with the bonding jumper even though we pull an EGC in.
 
If you go with flex or sealtite, or a expansion fitting without a jumper though, be careful if any run crosses more than one joint, 'cause even if you are running a wire-type EGC, the conduit needs to be grounded, and the flex probably won't qualify to bond the center section(s) of pipe.
 
philly said:
... a structural expansion fitting.
Click to expand...
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.
 
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