lock nuts on RGS couplings and myers hubs

[kwired]

Why would a Myers hub be a problem? If you install it correctly! Your point is mute!

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I think you missed the point, water gets inside - even a "raintight" fitting, hence the reason the interior of outside raceways is a wet location.

Myers hub with GRC not fully threaded into it is going to leak more then one that is fully threaded into it. But both still are subject to condensation forming within and there really is no point of trying to completely seal each and every fitting on any outside raceway system or even inside in an environment prone to condensing.

 

[al hildenbrand]

Now tell that to those that insisted on making/listing what we now call "raintight" EMT fittings.:roll:

"Telling that" is a matter of Public Record for decades prior to the change of the "Standard" for raintight EMT fittings. The NEC Article 100 Definition of the interior of a raceway exposed to weather as a Wet Location is unaltered by EMT standard. After the EMT raintight standard was changed, the NEC Article 100 Definition of Wet Location is the same as it was before the change in the standard.

 

[kwired]

"Telling that" is a matter of Public Record for decades prior to the change of the "Standard" for raintight EMT fittings. The NEC Article 100 Definition of the interior of a raceway exposed to weather as a Wet Location is unaltered by EMT standard. After the EMT raintight standard was changed, the NEC Article 100 Definition of Wet Location is the same as it was before the change in the standard.

Those that changed the standard apparently were not listening. I haven't found any brand of RT fittings yet that aren't a big pain to install compared to the standard compression fittings that once were acceptable for the purpose. You need to completely disassemble nearly all of them to install them, the tubing almost never wants to slip into an assembled (but loose) fitting.

I run a lot of 1/2 and 3/4 EMT outdoors, it does take longer to make up each fitting then it used to, when doing so in colder weather you sometimes can't even slip the nylon ferrule all by itself over the tubing, occasionally a few of them get thrown as far as I can throw them, along with some words I can't say here - leaving us with about the equivalent of a standard compression fitting.

 

[Smart $]

Read Article 100 Definition of "Fitting". A locknut is a fitting that is intended to provide "primarily" a mechanical, rather than electrical, function.

Primarily per Code, yes, but they are also means to assure grounding continuity. See 250.92 and 250.97. For electrical [grounding] continuity, the assembly must be investigated by the listing standard. The suggested assembly has not. Locknuts have only been investigated for grounding as securement of connectors or using two, one inside and one outside, to connect IMC/RMS to [hubless] enclosures.

 

[Daniel malack]

I think you missed the point, water gets inside - even a "raintight" fitting, hence the reason the interior of outside raceways is a wet location.

Myers hub with GRC not fully threaded into it is going to leak more then one that is fully threaded into it. But both still are subject to condensation forming within and there really is no point of trying to completely seal each and every fitting on any outside raceway system or even inside in an environment prone to condensing.

If you look at the design of the nema 3 enclosure you will see drain holes. Why? Because water will get into the enclosure! If you completely sealed the container it would cause many problems. Water gets in a nema 3 enclosure. Don't route your GEC through the weep holes.

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[al hildenbrand]

I haven't found any brand of RT fittings yet that aren't a big pain to install compared to the standard compression fittings that once were acceptable for the purpose.

I agree.

 

[kwired]

If you look at the design of the nema 3 enclosure you will see drain holes. Why? Because water will get into the enclosure! If you completely sealed the container it would cause many problems. Water gets in a nema 3 enclosure. Don't route your GEC through the weep holes.

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I totally agree on the NEMA 3 enclosure, but that has nothing to do with raceways. The interior of an outside raceway is a wet location.

Interior of a 3R enclosure may get water inside - you still may need to carefully select where you enter with raceways to avoid having water run onto components housed within the enclosure. Factory installed/factory optional hubs top dead center of a 3R enclosure are often the worst place you can enter such enclosure from my experiences. Any water entering that raceway runs right onto components installed in the cabinet/enclosure.

 

[al hildenbrand]

Primarily per Code, yes, but they are also means to assure grounding continuity. See 250.92 and 250.97.

The locknut is on the outside of the threaded conduit. The threaded conduit is the recognized grounding conductor, and the threaded conduit is threaded into the Myers hub threads establishing the electrical connection when "wrench tight".

Tightening the "mechanical" locknut tightens the threads, and that can easily be done to "wrench tight". The thread of the conduit to the thread of the hub is the electrical continuity path, and the locknut is used primarily mechanically.

 

[Daniel malack]

I totally agree on the NEMA 3 enclosure, but that has nothing to do with raceways. The interior of an outside raceway is a wet location.

Interior of a 3R enclosure may get water inside - you still may need to carefully select where you enter with raceways to avoid having water run onto components housed within the enclosure. Factory installed/factory optional hubs top dead center of a 3R enclosure are often the worst place you can enter such enclosure from my experiences. Any water entering that raceway runs right onto components installed in the cabinet/enclosure.

Not through a properly installed Myers hub.

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[Daniel malack]

The locknut is on the outside of the threaded conduit. The threaded conduit is the recognized grounding conductor, and the threaded conduit is threaded into the Myers hub threads establishing the electrical connection when "wrench tight".

Tightening the "mechanical" locknut tightens the threads, and that can easily be done to "wrench tight". The thread of the conduit to the thread of the hub is the electrical continuity path, and the locknut is used primarily mechanically.

No need for lock Nut! Unless you have a million of them on your truck and looking for a reason to get rid of them.

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[kwired]

Not through a properly installed Myers hub.

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Properly installed Myers hub may keep water from entering the joint between the hub and the enclosure, it will not stop any water within the raceway from entering the enclosure - which is what my comments have all been about. Same for a raintight EMT fitting. Condensation will occur in such outdoor raceways on nearly a daily basis as temps change in most of North America, may be less extreme in the Southwest but still likely does happen at times.

 

[Daniel malack]

Properly installed Myers hub may keep water from entering the joint between the hub and the enclosure, it will not stop any water within the raceway from entering the enclosure - which is what my comments have all been about. Same for a raintight EMT fitting. Condensation will occur in such outdoor raceways on nearly a daily basis as temps change in most of North America, may be less extreme in the Southwest but still likely does happen at times.

So what? Are you commenting just to comment?

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[Smart $]

The locknut is on the outside of the threaded conduit. [That's the only place it can be ] The threaded conduit is the recognized grounding conductor, and the threaded conduit is threaded into the Myers hub threads establishing the electrical connection when "wrench tight".

Tightening the "mechanical" locknut tightens the threads, and that can easily be done to "wrench tight". The thread of the conduit to the thread of the hub is the electrical continuity path, and the locknut is used primarily mechanically.

You are choosing your wording carefully to make it sound compliant. To be 100% comp[liant, the conduit must threaded wrench tight into the hub without the use of a locknut to meet the listing standard requirement for grounding continuity. Where it is, there's no need for a locknut. In fact, the locknut can prevent the conduit from being thread wrench tight into the hub.

 

[al hildenbrand]

So what? Are you commenting just to comment?

Daniel, go back to the OP (opening post) and the subsequent original poster's expanding of the details of this thread's specific subject of discussion.

We are talking about what constitutes a "correct" assembly of a Myers hub with threaded conduit. From your comments, you seem to say you know what that is, but you are not describing it. Let me ask you, how do you get the threads "mechanically tight" when you have to stop wrenching the threads 180 degrees BEFORE the threads "tighten"? (read the details back on page one.)

 

[al hildenbrand]

You are choosing your wording carefully to make it sound compliant.

Yes, I find it easy to describe a mechanical assembly that includes, as part of it, an effective fault clearing current path.

In my opinion, the language of the NEC fails to give you a means to divide the mechanical thread tightness into categories. If so, the "wrench" is going to have to be "listed" and "grounding and bonding" and more . . .

 

[kwired]

So what? Are you commenting just to comment?

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Daniel, go back to the OP (opening post) and the subsequent original poster's expanding of the details of this thread's specific subject of discussion.

We are talking about what constitutes a "correct" assembly of a Myers hub with threaded conduit. From your comments, you seem to say you know what that is, but you are not describing it. Let me ask you, how do you get the threads "mechanically tight" when you have to stop wrenching the threads 180 degrees BEFORE the threads "tighten"? (read the details back on page one.)

I veered off topic some with the EMT fittings comment, but doesn't change the fact that outdoor raceways get water inside them no matter how raintight any fittings are.

Meyers hub - as Al said is not as "raintight" when the conduit isn't threaded in until "wrench tight" and even then still could leak some but is still "raintight" enough considering the raceway probably gets more moisture inside as a result of condensation.