# Use of Myers Hub vs sealing locknuts.



## varmit (Apr 19, 2009)

Not sure about your inspector. Personally, I would have used a sealing ring/seal washer on the outside of the enclosure with the EMT connector. I have found the seal rings to work as well as Meyers hubs in keeping out water. The sealing locknuts, when only used on the inside of the enclosure, may eventually allow some water in. 

In reality, probably either method will seal as well as the EMT connector.


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## splatz (May 23, 2015)

This comes up a lot, I was digging around a bit this morning. I found NEMA 250, the standard NEMA publishes for electrical enclosures, which tells manufacturers what they have to do to make a NEMA 3R or other rated enclosure. 

The bit below is snipped from that standard. It's saying that the manufacturer is supposed to either 1) specify hubs to use, 2) include hubs, or 3) require hubs, but any way you look at it, hubs. I don't think it's a slam dunk for the inspector but it is looking bad for sealing locknuts, etc.


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## Southeast Power (Jan 18, 2009)

I think I'm screwed:

Entries into raintight enclosures

Q: What are proper methods for making conduit entries in the sides and back of a panelboard in a raintight enclosure? Are Meyers Hubs required or may weatherproof locknuts and bushings be used? Where are ordinary locknuts and bushings acceptable?

A: Where penetrations in the enclosure are made above a horizontal plane that includes electrical components such as busbars and overcurrent devices, the integrity of the enclosure must be maintained.

Generally, any holes that are made in the sides or back of the panelboard that are above the prepunched knockouts that are part of the enclosure must be sealed to prevent the entrance of rain, snow or sleet.

Sealing locknuts may be used where the wiring method is rigid metal conduit or intermediate metal conduit. One sealing locknut is required either inside or outside of the enclosure.

An ordinary locknut can be used on the opposite side of the enclosure or another sealing locknut may be provided. A bushing inside the enclosure completes the conduit entry.

https://www.ecmag.com/section/codes-standards/entries-raintight-enclosures-derating-nm-b-c


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## dronai (Apr 11, 2011)

So the 12x12x6 box is not a problem according to what you posted above right ?


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## kb1jb1 (Nov 11, 2017)

splatz said:


> This comes up a lot, I was digging around a bit this morning. I found NEMA 250, the standard NEMA publishes for electrical enclosures, which tells manufacturers what they have to do to make a NEMA 3R or other rated enclosure.
> 
> The bit below is snipped from that standard. It's saying that the manufacturer is supposed to either 1) specify hubs to use, 2) include hubs, or 3) require hubs, but any way you look at it, hubs. I don't think it's a slam dunk for the inspector but it is looking bad for sealing locknuts, etc.


I just finished a job re-doing a 38 kva generator installation. The initial electrician used plain PVC connectors on 3R and 4X equipment. I could see using them on the bottom but not on the top. The transfer switches are now swiss cheese so we moved everything inside. The homeowner might be suing the installer to recoup some of his expenses. The 250 standard will provide me with additional documentation as far as hubs being required. I want to back up my work as much as possible.


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## macmikeman (Jan 23, 2007)

Southeast Power said:


> I think I'm screwed:
> 
> Entries into raintight enclosures
> 
> ...


That article is prejudiced . No mention of Emt or PVC. I say it's not official. It's the author's opinion.


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## 220/221 (Sep 25, 2007)

I would guess that the inspector wasn't educated. 

The way I remember the code is that a sealing locknut serves the same purpose as a Meyers hub. I remember learning that on the internet and I stopped spending money on Meyers hubs.

I also think I had to educate a few inspectors on the issue.


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## MechanicalDVR (Dec 29, 2007)

I've been under the impression for a long time that top entries had to be a Meyers hub.


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## Southeast Power (Jan 18, 2009)

MechanicalDVR said:


> I've been under the impression for a long time that top entries had to be a Meyers hub.


I always use them when entering to the upper part of a panel or enclosure where it enters above the bus.
I want that concerned about entering the top of a junction box.


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## MechanicalDVR (Dec 29, 2007)

Southeast Power said:


> I always use them when entering to the upper part of a panel or enclosure where it enters above the bus.
> I want that concerned about entering the top of a junction box.



I was talking in an exterior application and see your point but inspectors rarely if ever use logic really.


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## 220/221 (Sep 25, 2007)

MechanicalDVR said:


> I've been under the impression for a long time that top entries had to be a Meyers hub.



So was I...... and so is the inspector 

I am 100% certain that a sealing lock nut is sufficient. I remember reading ithe code section (probably here) and started using them almost exclusively in lieu of Meyers hubs maybe a decade ago, when I was still working.


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## macmikeman (Jan 23, 2007)

We have inspectors here that will tell us to remove the Myers hubs when installing pvc conduit into the top of cans , and to replace them with sealing locknuts because the thread taper in their lofty understanding is different and moisture may penetrate thru that connection to the hub. I can demonstrate the opposite of that, but they always dig out like mad when I try to show them.


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## CoolWill (Jan 5, 2019)

The UL listing for sealing locknuts is for IMC and rigid only.


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## macmikeman (Jan 23, 2007)

CoolWill said:


> The UL listing for sealing locknuts is for IMC and rigid only.


As is the Myers hub. There is no product produced for emt or polyvinyl cloride
conduit. But that ain't gonna stop me from either using sealing locknuts or hubs with emt and pvc conduits into the top of pull boxes. That is the problem with the NEC. Head up ass. Remove the demands for listing if the listing agencies won't test the alternate products on their dime, or the manufacturer's of the boxes don't provide a hub or a paperwork describing which hubs are acceptable. They are all hiding behind each others ass- NEC, manufacture's , UL Labs. It's a circle jerk.


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## splatz (May 23, 2015)

220/221 said:


> So was I...... and so is the inspector
> 
> I am 100% certain that a sealing lock nut is sufficient. I remember reading ithe code section (probably here) and started using them almost exclusively in lieu of Meyers hubs maybe a decade ago, when I was still working.


https://www.electriciantalk.com/f2/myers-hub-68827/#post1282869


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## splatz (May 23, 2015)

Here's another article by a guy from UL. 

https://www.ecmag.com/section/codes-standards/fittings-hubs

He's making sense and I am kind of going along with him until I think about his argument that a straight thread into a tapered thread wouldn't make solid electrical contact and there might be arcing in the gaps between the threads


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## Southeast Power (Jan 18, 2009)

splatz said:


> Here's another article by a guy from UL.
> 
> https://www.ecmag.com/section/codes-standards/fittings-hubs
> 
> He's making sense and I am kind of going along with him until I think about his argument that a straight thread into a tapered thread wouldn't make solid electrical contact and there might be arcing in the gaps between the threads


I had the inspection today.
I tried to make a case for sealing locknuts.
The inspector insisted that if I were entering the upper side of of a panelboard, sealing locknuts would be acceptable. 
The Myers hubs are, according to the inspector, required when entering the top of an enclosure. 
So screw it, tonight at midnight, I will begin the process of misusing a couple of myers hubs .


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## joe-nwt (Mar 28, 2019)

Southeast Power said:


> I had the inspection today.
> I tried to make a case for sealing locknuts.
> The inspector insisted that if I were entering the upper side of of a panelboard, sealing locknuts would be acceptable.
> The Myers hubs are, according to the inspector, required when entering the top of an enclosure.
> So screw it, tonight at midnight, I will begin the process of misusing a couple of myers hubs .


Did you ask for a code reference?


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## Southeast Power (Jan 18, 2009)

joe-nwt said:


> Did you ask for a code reference?


The problem I had was that there is no approved use for either a sealing locknut or a Myers hub with an EMT fitting so, I caved.

In a perfect world, I would have to install a Myers hub, install a close nipple, then a rigid threaded coupling, then an EMT compression connector and that would even be a problem as they do not sell weather proof compression connectors in our jurisdiction.


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## 7635tools (Nov 10, 2013)

If using EMT, why not use rain tight EMT connectors. A bit more expensive than regular compression fittings but cheaper than Meyers hubs. 


Sent from my iPhone using Tapatalk


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## Southeast Power (Jan 18, 2009)

There it is.
I feel so dirty.


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## Southeast Power (Jan 18, 2009)

7635tools said:


> If using EMT, why not use rain tight EMT connectors. A bit more expensive than regular compression fittings but cheaper than Meyers hubs.
> 
> 
> Sent from my iPhone using Tapatalk


I cant seem to locate them here in SE Florida when I need them.


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