Myers Hub terminating into Cabletray

[archimedes]

I wanted to know if this setup would be a violation of the NEC. I have a 3/4" IMC conduit that 90's into an LB conduit body. The conduit body has a 3/4" IMC nipple that is approximately 4.5" long, and ends in a Myers hub. The hub end of the nipple has then been fastened securely into the side of 12" Cope cabletray via an 1.125" hole in the tray. The conduit is supported securely via the NEC instructions for IMC conduit.

In article 392.6(J) it states, "For raceways terminating at the tray, a listed cable tray clamp or adapter shall be used to securely fasten the raceway to the cable tray system..."

Would a Myer's hub constitute as an adapter? Would this be acceptable for grounding purposes?

 

[weressl]

I wanted to know if this setup would be a violation of the NEC. I have a 3/4" IMC conduit that 90's into an LB conduit body. The conduit body has a 3/4" IMC nipple that is approximately 4.5" long, and ends in a Myers hub. The hub end of the nipple has then been fastened securely into the side of 12" Cope cabletray via an 1.125" hole in the tray. The conduit is supported securely via the NEC instructions for IMC conduit.

In article 392.6(J) it states, "For raceways terminating at the tray, a listed cable tray clamp or adapter shall be used to securely fasten the raceway to the cable tray system..."

Would a Myer's hub constitute as an adapter? Would this be acceptable for grounding purposes?

You should not drill the side-rail of a cable tray, it mechanically weakens it and would be voiding its approval.

There are conduit clamps that fasten the conduit - carying the tray cable - to the top or the bottom of the siderail flange. The conduit only needs a nylon pop-off bushing on the end to prevent the cable from abrainding.

 

[ZZDoug]

Welcome to the forum, but like most people here you arent accurately describing the situation. I have run miles of cable tray but never heard of Cope, I presume you are talking about standard ladder type tray with 6" side rails. When you say 12" I assume you mean the width of the tray, which is irrelevant. It sounds like you are talking about going into the side of the tray (through the side rail) with the Myers hub. And you have essentially answered your own question, its a matter of whether a Meyers hub is listed for this purpose, which I would doubt. Just look it up. However, even though technically illegal, as long as it was in the top portion of the side rail I dont see anything wrong with it. You might very well be able to get an open minded inspector to give you an exception on this. But the case could also be made that a hole that of size weakens the rail, we drill 1/2" holes regularly for bonding jumpers, but over an inch on a 6" (?) rail could be an issue.

 

[archimedes]

I was using the brand name to identify the style, and the 12" was indeed the width...the heighth was 6". The installation is mechanically sound, and the inspector DID pass it, but I wanted to know whether or not it violated any specific code. Myers hubs are only listed for specific NEMA enclosures, and are not for cabletray, which answers my question I guess.

I was not aware that drilling into the side-rail of cable tray voided its approval. Can you provide me with a link for this? Most cable tray needs to have holes drilled into it anytime you're not running a complete length, so as to have holes for the carriage bolts to go through for the coupling. More information on this would be appreciated, and thanks for the quick responses.

 

[augie47]

Mr. Weress quoted the Code Article we used when questioning a similar install on some foreign made tray. (In article 392.6(J) it states, "For raceways terminating at the tray, a listed cable tray clamp or adapter shall be used to securely fasten the raceway to the cable tray system...")
Our position was that, based on this Article, drill a hole for conduit entry was a violation.
That particular CT manufacturer did not show adapters in their catalog and provided a engineering letter allowing the holes to be drilled.
(note the CT was not being used as an equipment ground and their documentation stated the listing was for it's use as a EGC)

 

[weressl]

I was not aware that drilling into the side-rail of cable tray voided its approval. Can you provide me with a link for this? Most cable tray needs to have holes drilled into it anytime you're not running a complete length, so as to have holes for the carriage bolts to go through for the coupling. More information on this would be appreciated, and thanks for the quick responses.

Cable trays are structural supports and the testing process for UL approcal involves mechanical loading of the tray. There are specific instructions on splicing them and one of the objective of how that splicing is done to restore the same structural strength as the unspliced run length. If you have a wooden stick and you drill a perpendicular hole into it, where do you think the stick will break if you bend it?

ZZDoug: you gotta get out more often. Cope IS one of the major tray suppliers.:grin:

http://www.atcelectrical.com/site_cope/site_metaltray/index.php

 

[ZZDoug]

Hey archimedes, I think most people in the trade, including most inspectors, would think this isnt legal. I just looked in the Nema Cable Tray Installation Guidelines and there is nothing mentioned. However, up here in Alaska B-Line tray is the standard, and in their latest cable tray manual here is what they say;

"There are some special installations where the use of conduit knockouts in the cable tray side rail for terminating conduit is appropriate. This would not be a good standard practice because it is costly and labor intensive, and if randomly used may result in damaging and lowering the strength of the cable tray."

So evidently B-Line does allow it although discouraging its use. Again I am not familiar with Cope, but as auggie mentioned, getting a letter from the manufacturer would make it good to go.

 

[ZZDoug]

ZZDoug: you gotta get out more often. Cope IS one of the major tray suppliers.

Up here in Alaska tray is used much much more than any place I have seen in the lower 48, but I can't recall using that brand. Maybe just don't remember or a coincidence, but B-Line is far and away the choice up here. Don't know why. As far as getting out more, well, Alaska isn't exactly the normal world ya know. But we definitely have some outside to get into.....

 

[archimedes]

The concensus seems to indicate that it is a code violation, and I'm inclined to agree now. Apparently we've been installing conduit into cable tray wrong for the past 3 years at the industrial plant at which I'm currently working. If we didn't drill into the side of the tray with a hole saw, we were either utilizing u-bolts through the upper lip of the tray for larger pipe, or we were using split rings attached via drilled holes in the tray's lip, with a bolt going through into the ring's base. In those situations we bonded to the tray via IGB's and a lug bolted to the lip of the tray. I'm starting to think that the bonding methods may also be wrong as well now, since the drilling of holes into the tray is frowned upon. Not all of the tray we have used has been cope, we have used B-Line as well. Cope seems to use the round rungs, and B-Line uses the square shaped ones.

I'm a 3rd year apprentice, so I haven't really questioned the methods that were being taught to me until recently, and I'm glad I have. Thank you very much for all your input, it's greatly appreciated.

 

[dicklaxt]

If you have a Crouse Hinds Catalog handy, look up a LCC Series Cable Tray Clamp,there are others that are an equal but thi type is the only one approved that I know of.

You probably find it on line under Crouse's product catalog.There are several tray manufacturers and Cope is one of the biggies.

dick

 

[weressl]

Hey archimedes, I think most people in the trade, including most inspectors, would think this isnt legal. I just looked in the Nema Cable Tray Installation Guidelines and there is nothing mentioned. However, up here in Alaska B-Line tray is the standard, and in their latest cable tray manual here is what they say;

"There are some special installations where the use of conduit knockouts in the cable tray side rail for terminating conduit is appropriate. This would not be a good standard practice because it is costly and labor intensive, and if randomly used may result in damaging and lowering the strength of the cable tray."

So evidently B-Line does allow it although discouraging its use. Again I am not familiar with Cope, but as auggie mentioned, getting a letter from the manufacturer would make it good to go.

That paragraph from B-Line is a legally indefensible position. Any installation instruction or modification of such should be quantified. That would mean that each different siderail configuration, each different rung configuration, each different support span should specify how many holes in the siderails allowed, what their sizes should be, what distance from each other and so on.

There have been some court cases resulting from injuries of weakened and overloaded tray and OSHA has stepped up its scrutiny of installation wherever an inspection is warranted.

 

[markstg]

NEMA VE2 is the standard for cable tray installation and therein it shows how conduits are attached to cable tray. Clamps are shown, not drilling the siderail.

 

[Smart $]

... The conduit only needs a nylon pop-off bushing on the end to prevent the cable from abrainding.

This depends on how the conduit terminates on the other end(s) of the run. The push-on bushing all that is required if the conduit is used only as a protective chase/sleeve [where a push-on bushing is all that is required on the other end(s)].

 

[weressl]

This depends on how the conduit terminates on the other end(s) of the run. The push-on bushing all that is required if the conduit is used only as a protective chase/sleeve [where a push-on bushing is all that is required on the other end(s)].

Correct. However it is both wasteful and impractical to install the conduit as a raceway, eg. a closed conduit system. In that case a CGB type fitting would be required to close off the conduit and secure the cable at the entry point. Multiple cables further complicate the issue.

 

[Smart $]

Correct. However it is both wasteful and impractical to install the conduit as a raceway, eg. a closed conduit system. In that case a CGB type fitting would be required to close off the conduit and secure the cable at the entry point. Multiple cables further complicate the issue.

Agreed.

I just brought it up because it is common pratice around here to mix the conduit systems... open on the tray end (typically with a "throated" connector, or connector with plastic bushing) yet the non-tray end(s) terminate to enclosures and such. Nobody seems to care much, including inspectors.

 

[jusme123]

If you have a Crouse Hinds Catalog handy, look up a LCC Series Cable Tray Clamp,there are others that are an equal but thi type is the only one approved that I know of.

You probably find it on line under Crouse's product catalog.There are several tray manufacturers and Cope is one of the biggies.

dick

http://www.crouse-hinds.com/catalog/PDFS/00099to00100.pdf

 

[weressl]

Agreed.

I just brought it up because it is common pratice around here to mix the conduit systems... open on the tray end (typically with a "throated" connector, or connector with plastic bushing) yet the non-tray end(s) terminate to enclosures and such. Nobody seems to care much, including inspectors.

A surefire way to fill up conduit with water and dirt in outdoor applications, not mention the rest of the violations.