Myers Hub for Outdoor Panel

[euclid43]

Do I have to install Myers Hubs at service panel for feeder cks? It's an outdoor panel, and I thought compression connectors with silicone would work.

 

[raider1]

Where will the feeder conduit enter the service?

Take a look at 312.2

I thought compression connectors with silicone would work.

I would not use rain tight compressions connectors with just silicone. Use a sealing lock ring to connect the RT compression connector.

Chris

 

[growler]

Do I have to install Myers Hubs at service panel for feeder cks? It's an outdoor panel, and I thought compression connectors with silicone would work.

You here this all the time. Would this work? It may very well work but is it an approved method.

approved: acceptable to the authority having jurisdiction.

 

[Sierrasparky]

I think the question asked is if a Raintight connector with a Sealing washer/ring is code complaint to install a raceway entering in th top of a panel
Or do you need to use a myers type hub?

 

[growler]

I thought compression connectors with silicone would work.

I think the question asked is if a Raintight connector with a Sealing washer/ring is code complaint to install a raceway entering in th top of a panel
Or do you need to use a myers type hub?

I would think that the newer compression connectors with sealing washers would be code compliant, they are listed for "wet" locations.

However not all compression connectors are raintight. Even some of the one's that people thought were raintight.

If you have one of the new rain tight connectors then you wouldn't need silicone. It will be marked "raintight" and have the washer/sealing ring/ thingy.

 

[infinity]

Where is the conduit entering? If it's below the live parts a standard locknut/connector would be complaint.

 

[raider1]

Where is the conduit entering? If it's below the live parts a standard locknut/connector would be complaint.

I agree, thats why I mentioned that the OPer should read 312.2.

Chris

 

[jrannis]

Sealing locknuts are only good for threaded conduit, not fittings.
Myers hubs are cheap and work just fine. If you are entering below the panel guts, just a regular compression connector rated for outdoor use will work.

 

[macmikeman]

Sealing locknuts are only good for threaded conduit, not fittings.
Myers hubs are cheap and work just fine. If you are entering below the panel guts, just a regular compression connector rated for outdoor use will work.

At the UL website there is a question and answer section that covers different listing issues. One article was about the use of Myers hubs and emt. The UL position was that emt in a Myers hub is against the listing. The reference is UL Question Corner, May 14, 2006.

 

[kwired]

At the UL website there is a question and answer section that covers different listing issues. One article was about the use of Myers hubs and emt. The UL position was that emt in a Myers hub is against the listing. The reference is UL Question Corner, May 14, 2006.

I used to use myers hubs with emt fittings, then they came up with the fittings that are supposed to be raintight with the rubber washer included.

I stopped using the myers hubs because the rubber washer should seal the opening in the enclosure.

recently went back to a job done one year ago to do some additional work and saw that many of the rubber washers were deteriorated enough that I questioned wether they were sealing the opening anymore. Now I plan to use myers hubs again and don't care if they are not listed. The testing labs can not tell me that the original install did not seal.

When they first came out with the "raintight" fittings I thought they were a joke. Sure the extra nylon ferrules in the fitting probably will keep out more water. But I don't believe are necessary unless you are talking about high pressure water maybe.

A metal raceway installed outdoors gets more water inside from condensation then it will ever get from rain. I may even be willing to bet that a set screw fitting (if it is a pretty tight fitting one) will hold out more rain than what condenses within the raceway.

 

[macmikeman]

I used to use myers hubs with emt fittings, then they came up with the fittings that are supposed to be raintight with the rubber washer included.

I stopped using the myers hubs because the rubber washer should seal the opening in the enclosure.

recently went back to a job done one year ago to do some additional work and saw that many of the rubber washers were deteriorated enough that I questioned wether they were sealing the opening anymore. Now I plan to use myers hubs again and don't care if they are not listed. The testing labs can not tell me that the original install did not seal.

When they first came out with the "raintight" fittings I thought they were a joke. Sure the extra nylon ferrules in the fitting probably will keep out more water. But I don't believe are necessary unless you are talking about high pressure water maybe.

A metal raceway installed outdoors gets more water inside from condensation then it will ever get from rain. I may even be willing to bet that a set screw fitting (if it is a pretty tight fitting one) will hold out more rain than what condenses within the raceway.

Kwired, I just posted what the UL says, not what I think about the issue. I am in agreement with your statements, I also think the new listed RT connectors and couplings are pretty bogus in general. Yes Myers have worked great with emt for as long as I have been doing this trade, but UL says otherwise. They do testing and they have lab coats, I don't, so my opinions are of no value anywhere except the area where my shadow hits the floor. I slide slightly undersized o-rings onto emt, use standard off the shelf raintite couplings and connectors, roll the o-rings tight to the fitting and hold them in place with a dab of silicone all around. That lasts longer and works better than the listed RT connectors and couplings that cost 5 times what the regular compression couplings do. Haven't failed any inspections for doing it this way yet.....

 

[Sierrasparky]

Kwired, I just posted what the UL says, not what I think about the issue. I am in agreement with your statements, I also think the new listed RT connectors and couplings are pretty bogus in general. Yes Myers have worked great with emt for as long as I have been doing this trade, but UL says otherwise. They do testing and they have lab coats, I don't, so my opinions are of no value anywhere except the area where my shadow hits the floor. I slide slightly undersized o-rings onto emt, use standard off the shelf raintite couplings and connectors, roll the o-rings tight to the fitting and hold them in place with a dab of silicone all around. That lasts longer and works better than the listed RT connectors and couplings that cost 5 times what the regular compression couplings do. Haven't failed any inspections for doing it this way yet.....

Nice methhod but is it code compliant?

 

[realolman]

Kwired, I just posted what the UL says, not what I think about the issue. ........... Yes Myers have worked great with emt for as long as I have been doing this trade, but UL says otherwise. They do testing and they have lab coats, ......

I have never seen a myers hub for emt.... not arguing... I'd like to know about it.

All the meyers hubs I've ever seen were for threaded conduit... what does UL say about meyers hubs with RMC?

Where can I read about what UL says about a particular fitting ?

I know there have been some debates here about the liquid tightness of RMC and couplings... I know you can use it in wet locations... they should make liquid tight RMC couplings that actually are liquid tight, and be done with it.

I usually put pipe dope on it.... lately I been puttin' silicone on about everything... including my toast.

 

[Conduit Phil]

I used to use myers hubs with emt fittings, then they came up with the fittings that are supposed to be raintight with the rubber washer included.

I stopped using the myers hubs because the rubber washer should seal the opening in the enclosure.

recently went back to a job done one year ago to do some additional work and saw that many of the rubber washers were deteriorated enough that I questioned wether they were sealing the opening anymore. Now I plan to use myers hubs again and don't care if they are not listed. The testing labs can not tell me that the original install did not seal.

When they first came out with the "raintight" fittings I thought they were a joke. Sure the extra nylon ferrules in the fitting probably will keep out more water. But I don't believe are necessary unless you are talking about high pressure water maybe.

A metal raceway installed outdoors gets more water inside from condensation then it will ever get from rain. I may even be willing to bet that a set screw fitting (if it is a pretty tight fitting one) will hold out more rain than what condenses within the raceway.

I noticed the same issue with the rubber washers after only a few months on the Halex raintight EMT fittings. What brand were you using? Are the other brands any better?

 

[e57]

IMO going into the top of an NEMA3 panel with EMT is just bad practice anyway. But all of the problems with it can be solved by large emounts of paint...

 

[benaround]

Myers Hubs are for use with IMC or RMC.

 

[LJSMITH1]

Meyers Hubs have a female tapered thread (NPT) and are designed to be mated with RMC or IMC male NPT threads. They are not designed to work with straight threads (NPS), typically found on connector fittings. There are also production variations of those fitting threads that may allow one brand connector to screw into a Meyers hub, while another brand will not. This does not mean it works. Fittings supplied with locknuts have straight threads and will typically bind in a female tapered thread after only 2-3 turns at best.

If you use an EMT RT compression connector with a Meyers Hub you will not have a listed RT installation. This fitting combination has not been tested to be able to handle the mechanical, electrical, or environmental requirements of UL514B (and related NEC requirements).

As for the Raintight issue, all fittings that claim Raintight are tested to UL 514B section 8.6. This involves assembling the fitting and conduit to a sealed enclosure and exposing it to a defined water spray for 1 hour (its not a mist, but a moderate rainstorm). Absolutely no water or moisture is allowed inside the fitting, enclosure or conduit. The test is conducted with the fitting mounted in a vertical position as to maximize the exposure to the rain. There is no water pressure or submersion applied to the Raintight Fitting.

Macmikeman - You are mis-informed as to the validity of the listing process. The tests are real, and certainly do evaluate the capability of a fitting to withstand rainy conditions. The sealing rings absolutely work - especially if there is a split gland ring. If you have a solid gland ring (like T&B's steel RT fitting), the fitting keeps the rain out as long as the installer adequately tightens the gland nut. Those fittings need a bit more pressure to deform the metal gland ring enough to make it watertight.

Kwired - A setscrew fitting will never hold out a beating rain outdoors - unless its mounted upside down. The addition of those little sealing rings absolutely made the difference in making a compression fitting consistently Raintight.

As for longevity of the Raintight seals, well, that is up to the manufacturer and the quality of the materials they use. I have seen some KO seals made of closed cell foam that I know won't last more than 1-2 years outdoors due to Ozone, UV, and temperature extremes. That is a problem with material selection, not necessarily the design. The better fittings will use Buna-N or HDPE sealing materials, which should last many years without a problem.

 

[macmikeman]

If you use an EMT RT compression connector with a Meyers Hub you will not have a listed RT installation. This fitting combination has not been tested to be able to handle the mechanical, electrical, or environmental requirements of UL514B (and related NEC requirements).

That is what I was pointing out, not disputing it.

Macmikeman - You are mis-informed as to the validity of the listing process. The tests are real, and certainly do evaluate the capability of a fitting to withstand rainy conditions. The sealing rings absolutely work - especially if there is a split gland ring. If you have a solid gland ring (like T&B's steel RT fitting), the fitting keeps the rain out as long as the installer adequately tightens the gland nut. Those fittings need a bit more pressure to deform the metal gland ring enough to make it watertight.

Nope, sorry I am not mis-informed as to the validity of the listing, that is your assumption. I am however of the opinion that the original RT connectors served the intended purpose for decades. I have seen dedigration of the seals on new RT connectors with my own eyes. The use of Myers Hubs with emt rt connectors on 3r side and top entrys is a locally enforced issue where I am located. I have long been of the opinion that that enforcement is incorrect, and the use of the new RT connectors strait to the subject boxes without having to add a Myers is compliant to the code and the UL listing.

 

[LJSMITH1]

That is what I was pointing out, not disputing it.

I know, and this comment was not directed towards you.

Nope, sorry I am not mis-informed as to the validity of the listing, that is your assumption. I am however of the opinion that the original RT connectors served the intended purpose for decades. I have seen dedigration of the seals on new RT connectors with my own eyes. The use of Myers Hubs with emt rt connectors on 3r side and top entrys is a locally enforced issue where I am located. I have long been of the opinion that that enforcement is incorrect, and the use of the new RT connectors strait to the subject boxes without having to add a Myers is compliant to the code and the UL listing.

If decades of RT connector installations worked, then why did UL feel the need to undertake a field study back in 2000 to determine if these fittings were doing the job? Apparently, there were numerous water intrusion instances nationwide that caused scrutiny of the UL514B test methods, and the resulting de-listing of all RT listed product at that time. In all instances, it was not the workmanship, but the design and production variables of the fitting and related components that resulted in the failures. By adding the seals, there is now less of a likelihood of the installer making an error in assembly or the need to excessively compensate for natural production dimension tolerances.

If your local AHJ's are enforcing the use of locknut RT compression fittings with Meyers Hubs, then they are most certainly mis-informed, and should be shown these UL documents to educate them:

http://www.ul.com/global/eng/documents/offerings/perspectives/regulators/electrical/afci/iaei/septoct2004.pdf

http://www.ul.com/global/eng/documents/offerings/perspectives/regulators/electrical/afci/iaei/mayjune2006.pdf

http://www.ul.com/global/eng/documents/offerings/perspectives/regulators/electrical/afci/iaei/julyaug2003.pdf

I know that you understand all of this.

 

[Don S.]

I?m old, industrially oriented, highly opinionated, and I can?t help it. Regardless of what the code allows, EMT installed outdoors is not a good idea. Having to enter an enclosure from the top is bad enough without penny pinching around the purchase of a Myers hub. Water tight, in most instances is a fantasy, so violation of the enclosure by drilling a drain hole in the bottom will, at least, let the water that gets in, get back out.