MC Feeder Bonding Help

[THelmuth3]

Hello,
Long time reader, first post. I ran 3 - 200 amp 3 phase MC feeders in a warehouse from the 600 amp exterior meter main We have not landed the wire yet because service is not installed. Our inspector was here for rough inspection today and brought up an issue. We only have 8 1/2" to make the 90 degree turn to get into the back of the disconnects so I got 90 degree MC fittings to make the turn.
Our inspector asked how we were going to get into the back of the disconnects with the 90s without extending them which he said would not provide the bonding path required. There is a chance that the inside of the 90 will bottom out on the sheathing and our threads will not quite reach into the disconnect. I figured on 2" rigid couplings and a rigid nipple and locknuts if we had to extend them but he is saying this would not be an acceptable method. I am trying to figure out in the code where this would not be acceptable and what an acceptable method of extending these would be. Any input would be appreciated. Thanks
TH

 

[infinity]

I agree with the inspector the coupling is not code compliant. What about a conduit body, nipple and some transition to the MC cable?

 

[electrofelon]

There is a chance that the inside of the 90 will bottom out on the sheathing and our threads will not quite reach into the disconnect. I figured on 2" rigid couplings and a rigid nipple and locknuts if we had to extend them but he is saying this would not be an acceptable method. I am trying to figure out in the code where this would not be acceptable and what an acceptable method of extending these would be. Any input would be appreciated.

Perhaps I am not understanding what you are doing, but I would think any 90 degree connector (and every one I have used) would not have this issue?

http://www.aimedia.co/media/line-drawings/850A-856A.pdf

 

[ActionDave]

Perhaps I am not understanding what you are doing, but I would think any 90 degree connector (and every one I have used) would not have this issue?

http://www.aimedia.co/media/line-drawings/850A-856A.pdf

I think he is saying he would need a 2" rigid coupling because of the bending radius of the large diameter mc and the tight clearance going into the panel the sheathing of the mc would hit the cabinet. Kinda like what happens when you try to run an emt 90 around an outside corner.

 

[ActionDave]

Hello,
Long time reader, first post. I ran 3 - 200 amp 3 phase MC feeders in a warehouse from the 600 amp exterior meter main We have not landed the wire yet because service is not installed. Our inspector was here for rough inspection today and brought up an issue. We only have 8 1/2" to make the 90 degree turn to get into the back of the disconnects so I got 90 degree MC fittings to make the turn.
Our inspector asked how we were going to get into the back of the disconnects with the 90s without extending them which he said would not provide the bonding path required. There is a chance that the inside of the 90 will bottom out on the sheathing and our threads will not quite reach into the disconnect. I figured on 2" rigid couplings and a rigid nipple and locknuts if we had to extend them but he is saying this would not be an acceptable method. I am trying to figure out in the code where this would not be acceptable and what an acceptable method of extending these would be. Any input would be appreciated. Thanks
TH

Would a 45 degree flex connector work? They are not always on the shelf at the supply house but they can be ordered.

 

[electrofelon]

I think he is saying he would need a 2" rigid coupling because of the bending radius of the large diameter mc and the tight clearance going into the panel the sheathing of the mc would hit the cabinet. Kinda like what happens when you try to run an emt 90 around an outside corner.

Ok, that makes sense, but then I reread the OP a few times and I think what it is is they need to be extended to get past the exterior wall finish and into the wall cavity.

 

[electrofelon]

Here we go with this again, but what code would be violated using the RGS nipple idea? Do the destructions say only for use with a cabinet and locknut?

 

[ActionDave]

Here we go with this again, but what code would be violated using the RGS nipple idea? Do the destructions say only for use with a cabinet and locknut?

It's a UL testing and approved thing. RMC couplings are only, tested and listed with tapered threads. I don't care, I use them all the time with flex connectors and chase nipples. It's prolly violated as much as prohibition and the 55mph speed limit and needs to be done away with as well.

 

[electrofelon]

It's a UL testing and approved thing. RMC couplings are only, tested and listed with tapered threads. I don't care, I use them all the time with flex connectors and chase nipples. It's prolly violated as much as prohibition and the 55mph speed limit and needs to be done away with as well.

Yeah I think its bogus too. But OP seemed to say inspector was concerned about bonding, which I dont think is an issue if the other end is bonded.

Going with the above idea that bonding is only necessary on one end, what about the 90, then PVC FA then box adapter or TA?

 

[THelmuth3]

Thanks for the replies. Lots of good points I didn't think about. The 45 degree connector is an option. I will contact the inspector and ask if one end being bonded is sufficient. I just did not understand why an RMC coupling and nipple would not be sufficient for bonding. I will keep you posted. Thanks for the help.