Bonding a myers hub

[sparkymike]

We have multiple Myers hubs installed on a 1/2" steal plate in the floor of a MOD. The floor is two layers with insulation in between. The top part of the floor is removed and a cabinet is mounted above the opening with the area boxed in to create a box for the conductors to run into the bottom of the cabinet. The cable that is connected to the Myers hub is 3/500 MC-HL with ground. The problem is the Myers hub will only except #6 per it's UL listing and the code requires it to be 2/0 because of the service size. Hubbell said the UL listing will be void if anything larger tan #6 is used. The plate that the Myers hub is connected to is bonded with a 4/0 to the service equipment. Where in the code does it help me with the correct size needed for the Myers hub?

 

[Dennis Alwon]

I am not sure I understand. What kind of raceway do you have? Is this myers hub just connected to the plate with no raceway?

 

[sparkymike]

The raceway is the MC-HL cable that is connected to the Myers hub with a TMCX2 connector and then the cable runs into the bottom of the cabinet that has the bottom of it cut out and mounted over the hole in the floor. In a sense the area from the plate where the Myers hub is connected becomes part of the cabinet.

Is there a way to upload a PDF drawing that shows the detail it will help make it clear?

 

[Smart $]

Are you AKsparky1's co-worker

http://forums.mikeholt.com/showthread.php?t=168124

I'm wondering why there is even a myers hub involved???

If the below-enclosure volume is boxed out, just install the MCHL connectors to bottom of box-out and put a bonding bushing on each connector.

Cut out bottom of cabinet for box out, install edging around cutout, string bonding conductor through bushing lugs (lay-in type) and terminate to box-out.

 

[sparkymike]

Are you AKsparky1's co-worker

http://forums.mikeholt.com/showthread.php?t=168124

I'm wondering why there is even a myers hub involved???

If the below-enclosure volume is boxed out, just install the MCHL connectors to bottom of box-out and put a bonding bushing on each connector.

Cut out bottom of cabinet for box out, install edging around cutout, string bonding conductor through bushing lugs (lay-in type) and terminate to box-out.

I may be his co-worker however I am unsure from the name. I uploaded a detail to help explain my question

 

[Dennis Alwon]

So the cable fits in the connector but the hub won't allow the conductor sizes that are in the cable? That seems odd.

 

[Dennis Alwon]

One of the op's post- his 2nd didn't appear because it hadn't been approved -- it is there now

 

[iwire]

I uploaded a detail to help explain my question

The detail makes me ask the same question as Smart. What is the reason for Myers hubs?

An interesting note is that those cable connectors may not be listed for use with the tapered threads of a Myers hub.

 

[augie47]

Very Interesting Problem.
Been searching Myers Hubs & TMC connectors looking for larger lugs but have found nothing and like others, I'm trying to visualize the requirement for the Myers hubs..

 

[sparkymike]

The Myers hubs are installed in the FAB shop where the MOD's are being built. Then the MOD is shipped to location and the cables are run between MOD's. The Myers hubs are there because if the TMCX's where installed without them and directly to the plate it would be difficult or even impossible in some situation to reach down inside and bond the TMCX's so the Myers hubs are used so they can be bonded prior to the switchgear being mounted over the hole in the floor. Then all that needs to be done is push the cables up through the opening and the bonding is already completed.

 

[augie47]

answers that !

 

[Smart $]

The Myers hubs are installed in the FAB shop where the MOD's are being built. Then the MOD is shipped to location and the cables are run between MOD's. The Myers hubs are there because if the TMCX's where installed without them and directly to the plate it would be difficult or even impossible in some situation to reach down inside and bond the TMCX's so the Myers hubs are used so they can be bonded prior to the switchgear being mounted over the hole in the floor. Then all that needs to be done is push the cables up through the opening and the bonding is already completed.

Take out the myers hubs. Install connectors without cable in them. Use a bonding locknut.

I see many make this excessive-cost error. They use fittings that require a jumper. A bonding locknut is also acceptable [250.92(B)(4)] while requiring less work and material.

If dead set on using a myers hub, get ones with a bonding locknut:

...and make sure the mounting plate is bonded.

BTW, using the hub is a violation. Hubs are listed for use with RMC/IMC... not a connector.

 

[sparkymike]

The bonding plate is bonding by welding a 3/8" stud to the plate and a 4/0 bolted to the stud the switchgear. You say that the hub is a violation and I am not arguing that but I am looking for something to point to that says just that. Is a bonding bushing required on service entrance conductors? I believe I know the answer but I am getting some push back. And the voltage is 13.8

 

[Smart $]

The bonding plate is bonding by welding a 3/8" stud to the plate and a 4/0 bolted to the stud the switchgear. You say that the hub is a violation and I am not arguing that but I am looking for something to point to that says just that. Is a bonding bushing required on service entrance conductors? I believe I know the answer but I am getting some push back. And the voltage is 13.8

http://ul.com/wp-content/uploads/2014/04/ul_ConduitHubs.pdf

Hubs are listed as conduit fittings.

 

[sparkymike]

Great reference thank you

 

[coop3339]

maybe you could bond to the plate with the #2s then daisy chain through the hubs with a #6 and hit the plate again.

 

[sparkymike]

That is exactly how we do it. The question was raised that we may need a larger wire for the daisy chain however Crouse Hinds said using a larger cable would void the UL listing. When I ask Crouse Hinds about installing a fitting into there hub they say that is a legal installation however I believe it is not. Crouse Hinds is very vague on what there product is listed for use and they don't want to say they cant be used for any installation because that hurts sales. And we use thousands of Myers hubs where I am at.