Grounding Myers Hub in Service Enclosure

[lkdiaZ]

1000A service has RMC conduits going to a metal pull box before arriving at Main Service Disconnect. RMC conduits are to be terminated at pull box using grounding myers hub similar to STG-10. The conduits contain 500KCM. The bonding jumper for this would have to be 1/0 AWG if I'm not mistaken. Cut sheet for this hub lists a max 4AWG cable. How do I bond the grounding hub with a 1/0AWG cable? I need Nema 3R connection.

 

[tom baker]

Is the 1/0 a common bonding jumper? Can you use individual bonding jumpers to each hub?
Or I recall meyers makes a bonding hub with a setscrew similar to a bonding locknut

 

[lkdiaZ]

My preference would be to use a lay in lug on each hub and run a continuous 1/0 across all hubs and then take to a ground lug in enclosure. No problem with using individual either but it still has to be 1/0.

 

[augie47]

If you used a continuous jumper it would have to be 12-1/2% of the total area of the conductors.
Individual jumpers would be 1/0.
I have changed the lugs to accommodate the larger conductors.

 

[infinity]

My preference would be to use a lay in lug on each hub and run a continuous 1/0 across all hubs and then take to a ground lug in enclosure. No problem with using individual either but it still has to be 1/0.

As Augie stated the #1/0 would not be large enough to bond all of the raceways at once. Your choices are individual bonding jumpers based on the size of the ungrounded condcutors in each raceway or a single bonding jumper based on the 12.5% of the combined ungrounded conductors size.

If the lugs are too small just change them.

 

[lkdiaZ]

Point noted on individual vs single. Thanks for that catch. Re the lug size - no issue with using a larger ground conductor than actually shown on their data sheet? That was the gist of my concern.

 

[lkdiaZ]

So after looking at the cut sheet again I'm wondering if I even have to go the grounding hub route. In attached cut sheet from Eaton, Item 5 says the serrations are service approved for grounding. Based on that I would argue that I don't have to worry about lugs and the grounding screw of the grounding type hub. The serrations are what's approved and they occur on both grounding and non-grounding type hubs. Interested in feedback from others on this.

 

[augie47]

That's interesting.
At one time a "myers" hub used in service installations had to be UL listed KDER (as opposed to DWTT) and they had the added bonding lug.
I winder if the ones you show are KDER listed ?

 

[lkdiaZ]

If you go to Eaton's Website and look up ST-10 as an example, it provides you with Certification Section. Included in this list is grounding and bonding as well as conduit fittings. When you go to the grounding and bonding (KDER) it only shows the grounding hubs under this certification. So ST-10 is not in KDER but STG-10 is. Even so. assuming that we use STG-10 to avoid any misinterpretation, the cut sheet still states that the serrations are listed as service grounding and therefore we could do away with any use of the grounding screw which it describes as for additional safety.

 

[augie47]

With STG-10 bring the one with the KDER listing it would seem logical that the jumpers were needed. On the other hand, that cut sheet is full of slightly ambiguous foot notes.
I can see a inspector nightmare
As a precaution I would use the STG-10 so jumpers could be easily added if required.