Meyers Hub

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texie

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Fort Collins, Colorado
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Electrician, Contractor, Inspector
Is a Meyers hub suitable for connecting metallic service raceway to an enclosure and be compliant for bonding? I know it is for a metallic feeder conduit, but I am unclear if this is OK for a service raceway. What say the UL White book?
 
Not sure about the White book but I would guess that it would need a bonding locknut, bonding bushing or bonding wedge.
 
From the UL Book


Grounding and Bonding Hubs ? Grounding and bonding hubs are
Listed hubs (see DWTT) provided with a Listed grounding or bonding
locknut. They serve in a manner similar to grounding and bonding bushings
except they are only for use with threaded rigid metal and intermediate
metal conduit. Grounding hubs provide the electrical continuity
required by NEC 250.92 at service equipment and the electrical continuity
required by NEC 250.97 for circuits rated over 250 V.
Click to expand...
 
infinity said:
Not sure about the White book but I would guess that it would need a bonding locknut, bonding bushing or bonding wedge.
Click to expand...
How would one put a standard bonding locknut, bonding bushing or bonding bushing on a myers hub?
I know that myers hubs are available with a nut that includes a grounding lug, but it is not clear to me that this in and of itself is the only thing makes them suitable for bonding a metallic service raceway. The reason I say this is many think that a hub creates a "threaded opening" that is suitable for services. But if you use that logic, why do they make them available with the locknut that includes a ground lug?
 
Dennis Alwon said:
From the UL Book
Click to expand...
Oh gee, the UL White Book language...clear as mud. Does this mean that there are 2 types of hub? One is the normal one we usually see with just a nut inside and one that has a ground lug and that makes it suitable for metallic service raceway bonding?
 
texie said:
Oh gee, the UL White Book language...clear as mud. Does this mean that there are 2 types of hub? One is the normal one we usually see with just a nut inside and one that has a ground lug and that makes it suitable for metallic service raceway bonding?
Click to expand...
My guess is they are both the same hub but equipped with different locknuts. I have seen ads or other publications mentioning the ones with the ground lug and have asked supplier if they had any of them before... they had no idea what I was talking about, so apparently nobody uses them around here anyway.
 
kwired said:
My guess is they are both the same hub but equipped with different locknuts. I have seen ads or other publications mentioning the ones with the ground lug and have asked supplier if they had any of them before... they had no idea what I was talking about, so apparently nobody uses them around here anyway.
Click to expand...
Yes, they are the same hub and all you have to do is change the nut for one that has the ground lug. In my area the nut with the ground lug is readily available. But my question is, is that nut with a ground lug what makes it suitable for bonding a metallic service raceway?
Would your AHJ accept one without the ground lug (and bonding jumper) as bonding for a metallic service raceway?
Sorry if I seem to be harping on this, but this has come up a lot for me recently. This just not seem clear to me.
Bottom line, is a myers hub without the ground lug suitable for bonding of a metallic service raceway?
 
kwired said:
My guess is they are both the same hub but equipped with different locknuts. I have seen ads or other publications mentioning the ones with the ground lug and have asked supplier if they had any of them before... they had no idea what I was talking about, so apparently nobody uses them around here anyway.
Click to expand...

Like these?

cch_cp_myers_220.jpg
 
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texie said:
Yes, they are the same hub and all you have to do is change the nut for one that has the ground lug. In my area the nut with the ground lug is readily available. But my question is, is that nut with a ground lug what makes it suitable for bonding a metallic service raceway?
Would your AHJ accept one without the ground lug (and bonding jumper) as bonding for a metallic service raceway?
Sorry if I seem to be harping on this, but this has come up a lot for me recently. This just not seem clear to me.
Bottom line, is a myers hub without the ground lug suitable for bonding of a metallic service raceway?
Click to expand...
I would sure hope it is, otherwise what is the ground lug really for? The other style without the lug is listed for grounding purposes otherwise.

That said, I really can't recall ever using a myers hub on a service raceway. If entering a meter socket or a 3R breaker panel I usually am entering via bolt on hubs, but there are always those cases where something has to be different, I just can't recall any where I have used a myers hub on a service raceway.
 
kwired said:
I would sure hope it is, otherwise what is the ground lug really for? The other style without the lug is listed for grounding purposes otherwise.

That said, I really can't recall ever using a myers hub on a service raceway. If entering a meter socket or a 3R breaker panel I usually am entering via bolt on hubs, but there are always those cases where something has to be different, I just can't recall any where I have used a myers hub on a service raceway.
Click to expand...

Ah, yes we're getting closer. Yes, one would normally have a bolted hub out of the top and bonding is not an issue.
But my issue is, in my neck of the woods, is that many use a myers hub(without the locknut with ground lug) with a GRC nipple, say, between a CT cabinet and a service disconnect to avoid having to bond the GRC nipple with bonding bushings and jumpers. I'm questioning if this is acceptable unless you use the locknut that has the ground lug and install a bonding jumper. And if that is true, why use a myers hub in a 3R application if you have to put bonding jumpers on them in any case? All you have done is spend a lot of money for a hub that is otherwise not required if you still have to use the lock nut that includes a ground lug and install bonding jumpers. In other words you could have used a GRC nipple and double locknuts with grounding bushings.
I'm back to my original question, are myers hubs listed as a bonding means for service raceways without the locknut that includes the ground lug? Many say yes as they provide a threaded opening and no additional bonding is required and that is why they use them.
 
You need a grounding locknut, bushing or wedge just like you would to terminate a threaded raceway such as RMC or IMC. According to what Dennis posted the hub comes with a bonding locknut.
 
I have a feeling some hubs are listed for grounding and bonding depending on the locknut. It states they are listed hubs provided with....
 
My understanding is that there is a difference between a grounding and a bonding hub. The grounding hub locknut has a provision to connect a bonding jumper to it, while the bonding hub locknut has a bonding set screw that bites into the enclosure to provide the required bonding. The White Book information that Dennis posted indicates that only the grounding type complies with 250.92 and 250.97.
This is what I would call a bonding hub, the previously posted ones, I would call grounding hubs.
 
I know in the past the box for some Myers type hubs I have used were marked "suitable for bonding and grounding" or something very similar. These are the ones with a standard nut. I was told some time ago that the hubs which include the grounding lug were primarily designed for non metallic enclosures.

I don't think Dennis post really tells us much. It just states that grounding type hubs are suitable for grounding. it doesn't state that hubs without a lug on the nut are not sutible for grounding/bonding.

In my 30 years in the trade I have never seen a Myers hub with a lug installed or even at the supply houses. Only in catalogs.
 
On a related subject, a Meyers hub is not listed for use with PVC and a male adapter...only threaded metal conduit.
 
OK, I think I got it figured out after studying the White Book and a little nudging from you guys.
As Dennis said, hubs are covered under DWTT and are suitable for normal grounding. It does not mention use for compliance with 250.92, however if you look at "related products" in DWTT it refers you to KDER which specifically states that KDER covers compliance to 250.92 for grounding and bonding hubs (which are the hubs with the lug on the lock nut).
So bottom line, if you are going to use a myers type hub in a metallic service raceway it has to be the type with the lug and use a bonding jumper. I my neck of then woods, many seem to think a standard hub without the lug (and jumper) is in compliance with 250.92, but after researching this, this is clearly not the case. Infinity wins.
 
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