Grounding 2" flex

[mull982]

Does anyone know, if the code requires any liquid tight flex 2" or greater to be bonded?

The reason that I ask is that the contractor when installing new motors in the plant is using flex to get between his rigid conduit and the motor terminal box. He is claiming that per the NEC the flex (2" or larger) needs to have a grounding conductor wrapped about it so that the rigid condiut and the terminal box are bonded. Anyone ever heard of this?

 

[iwire]

There are a few reasons you might have to do this, here are two, they are likely others.

1) The entire run is RMC and be used as the EGC, in that case you would have to jump the LFMC to complete the EGC path from the RMC to the terminal box.

2) The run is PVC underground with RMC only above ground, in that case a you would have to jump the LFMC to complete the EGC path from the terminal box back to the RMC.

Take a look at 250.118(6) and you will see the limited times you can use the LFMC as the EGC.

It depend on the size of the LFMC and the size of the over current protection.

It could also just be in the job specifications.

 

[KentAT]

I was taught that an external bonding jumper should not be wrapped around as it travels along the flex conduit. It should be run straight and parallel and tiewrapped instead. Not just for looks, there was suppoosedly a reason.

Is there truth to this?

 

[kspifldorf]

I hope not to offend anybody, but why does ANYONE ever not want to pull a ground wire. There has got to be a better way to save a dime.