Alternative to the Myers Hub

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Heather H

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I'm looking for an alternative to the Myers Hub for a watertight seal. We are penetrating a module wall (approx. 1/2" thick) with 4" RGS, embedded in concrete. The design originally called for a Myers Hub, but the threads aren't long enough. The penetration must be watertight, and the locknut/hub must be grounded. I have searched endlessly for a grounding, sealing locknut/hub and the only option with both requirements appears to be the Myers Hub. Additionally, the module penetrations are 5", giving us only 1/2" to play with, so Link-Seal won't work either. Any ideas? Thanks!
 
MAC702 said:
Rain? Constant splashing? Or something submerged?
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None of the above. The conduit will be embedded in concrete. Design engineering is requiring the watertight seal, not exactly sure why. They are submitting a design to have something fabricated, but I'm hoping to find something that will work a little sooner.
 
When I was doing parking structures a decade ago, we used duct tape around fittings and boxes to make them concrete-tight during the pour. Not allowed to do that anymore?

Granted, you may have Specifications that prohibit what Code allows, too.

They are submitting a design to have something fabricated...
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Ah, is this something needed for many installations and requires something quickly installed and not just modified for a one-time purpose?
 
MAC702 said:
When I was doing parking structures a decade ago, we used duct tape around fittings and boxes to make them concrete-tight during the pour. Not allowed to do that anymore?

Granted, you may have Specifications that prohibit what Code allows, too.



Ah, is this something needed for many installations and requires something quickly installed and not just modified for a one-time purpose?
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Unfortunately, the requirements on this project are very strict. The concrete isn't what they're concerned with, except maybe during the cure period. But there isn't any equipment installed yet. Honestly, it doesn't make any sense, but it isn't my call. They have some sort of hub drawn up and ready for fabrication, but there is a lot of paperwork involved in order to make it happen. I thought maybe I was missing something. Seems like we should be able to purchase just a grounding, sealing nut and use it on both sides of the module wall. I just can't find a locknut that has both features. Thanks, though.
 
Heather H said:
I'm looking for an alternative to the Myers Hub for a watertight seal. We are penetrating a module wall (approx. 1/2" thick) with 4" RGS, embedded in concrete. The design originally called for a Myers Hub, but the threads aren't long enough. The penetration must be watertight, and the locknut/hub must be grounded. I have searched endlessly for a grounding, sealing locknut/hub and the only option with both requirements appears to be the Myers Hub. Additionally, the module penetrations are 5", giving us only 1/2" to play with, so Link-Seal won't work either. Any ideas? Thanks!
Click to expand...

Is there room to cut squares just big enough for the hubs that can have a thinner chunk of metal bolted to the 1/2" plate and scilicon sealed? Or welded
 
Heather H said:
Haha! I wouldn't be very popular with the crew if I handed this to them for 10 penetrations!
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But is the enclosure itself being fabricated? Could the enclosure be purchased with the holes already cut and tapped?

According to this Eaton document their sealing lockwashers:
Only one sealing locknut is required to:
• Functionally replace rigid threaded enclosure connectors
• Provide raintight, watertight or oiltight seal in any position
• Provide positive ground connection
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http://www.cooperindustries.com/con...og-pdfs/conduit-locknuts-sealing-locknuts.pdf

The problem is that these locknuts do not provide a grounding lug.

Several thoughts:
1) Contact Eaton and see if they can supply loose PVC gaskets which could be used with their 'bonding locknuts'.
2) Fabricate a thin sheet metal component with a bonding lug on it, that would fit under the sealing locknut to provide the grounding connection.
3) Simply 'stack' a bonding locknut over a sealing locknut.

-Jon
 
Or better yet:
Thread the conduit long enough to permit sealing locknuts inside and out, and then leave enough thread for a grounding bushing needed for wire protection on the end of the conduit.

-Jon
 
Heather H said:
None of the above. The conduit will be embedded in concrete. Design engineering is requiring the watertight seal, not exactly sure why. They are submitting a design to have something fabricated, but I'm hoping to find something that will work a little sooner.
Click to expand...

I would look and see if a meyer's hub is concrete tight then.....
 
Can a fitting be water tight and NOT concrete tight?

I'm finding that Myers has a "through-bulkhead" fitting that is designed to go through thicker walls, and is available for up to 4" conduit.

I've found some pictures, but haven't been able to see exactly how it works yet.

Bottom of 2nd page: http://www.cooperindustries.com/con...mmercial-products/catalog-pdfs/myers-hubs.pdf

Or maybe a small watertight box attached to the outside of the wall with a close nipple with watertight lock rings, and then the standard Myers hub attached to that?

Or once you have a conduit nipple attached, just use a coupling to the incoming conduit?
 
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MAC702 said:
Can a fitting be water tight and NOT concrete tight?

I'm finding that Myers has a "through-bulkhead" fitting that is designed to go through thicker walls, and is available for up to 4" conduit.

I've found some pictures, but haven't been able to see exactly how it works yet.

Bottom of 2nd page: http://www.cooperindustries.com/con...mmercial-products/catalog-pdfs/myers-hubs.pdf

Or maybe a small watertight box attached to the outside of the wall with a close nipple with watertight lock rings, and then the standard Myers hub attached to that?

Or once you have a conduit nipple attached, just use a coupling to the incoming conduit?
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http://www.aifittings.com/catalog/emt/emt-rain-tight-compression-connectors/

Notice that it implies both rain and concrete tightness. Haven't seen any listing for meyers hubs being concrete tight, lots of other situations they can be used and they are listed for them but concrete is never mentioned, as far as I have seen. So unless its not buried in concrete, I would ask if they thought of that, they already didn't think about how meyers hubs are meant to be used on thin metal...

Edit Also the bulk head fittings have differnent threads opposite the NPT I think its a NPSL???
 
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winnie said:
Or better yet:
Thread the conduit long enough to permit sealing locknuts inside and out, and then leave enough thread for a grounding bushing needed for wire protection on the end of the conduit.

-Jon
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This is also the least expensive route. BTW, only the sealing locknut on the outside of the enclosure is required. You can use a bonding locknut and plastic, composite, or plain metal bushing on the inside if the 'module' is metallic.

If the 'specifiers' are bound and determined to use a hub type interface before I went totally custom, I'd go with a space saver hub by OZ Gedney (http://www.emersonindustrial.com/en...t_hub/OZG_Threaded_Rigid_IMC_Conduit_Hubs.pdf). It amounts to a female Myers hub. If the male insert is too short use a nipple (check standard NPT thread works first), and one of the locknut/bushing combos to complete the interface.

If it's not the OZ Gedney model, I know there is a model that'll work... perhaps, T&B? Been a long time since I used one.
 
Russs57 said:
You want a bulkhead fitting.
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A bulkhead fitting will work but that's more for a continuation of a run than a termination. A description is it is like two female [-connection] hubs with a nipple in between.

The hub I noted earlier will accommodate a wall thickness up to 0.72" in the 3" model using the provided male insert.
 
If fabricating the enclosure - weld a coupling to the enclosure wall. Should be no need for a grounding bushing as the coupling is now effectively a part of the enclosure, can still leave full opening and thread a chase nipple into the interior side if an abrasion bushing is desired.
 
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