Bridal Rings or J-Hooks for THWN conductors

Status
Not open for further replies.
luckylerado

luckylerado

Senior Member
Location
Lake of the Ozarks
Been asked to comment on an installation of several sets of 480V Ckts ran in J-Hooks. The cables are failing megger testing and I am doing a kind of autopsy on the install. One of the things jumping out at me are the J-hooks. These are in an underground concrete trench meant for electrical feeders with the J-hooks attached to the walls. I have done some searching and I believe certain sheathed cables may be installed this way but I have no reason to believe that individual bundles of THWN-2 would be compliant. Can anyone offer a code reference that clearly states this is not allowed. This is not something I would have even considered doing but if it is compliant then I will just shake my head concede.
 
luckylerado said:
Been asked to comment on an installation of several sets of 480V Ckts ran in J-Hooks. The cables are failing megger testing and I am doing a kind of autopsy on the install. One of the things jumping out at me are the J-hooks. These are in an underground concrete trench meant for electrical feeders with the J-hooks attached to the walls. I have done some searching and I believe certain sheathed cables may be installed this way but I have no reason to believe that individual bundles of THWN-2 would be compliant. Can anyone offer a code reference that clearly states this is not allowed. This is not something I would have even considered doing but if it is compliant then I will just shake my head concede.
Click to expand...

If they are in a trench type raceway I think it is compliant. I don't recall there being any prohibition on securing wires in this way inside a legal raceway. How is this worse than having to secure them in vertical raceways?
 
Last edited:
jimdavis said:
I believe 300.3(A) would require individual THWN-2 conductors to be installed in a chapter 3 wiring method.
Click to expand...

300.3 Conductors.
(A) Single Conductors. Single conductors specified in Table
310.104(A) shall only be installed where part of a recognized
wiring method of Chapter 3.
Click to expand...

That is why I mentioned it would need to be a raceway type trench.
 
although I've seen it done, when I look at jimdavis's comment and search Code I tend to agree with him. I cant see where the individual cables are approved for trench installations.
 
jimdavis said:
I am wondering if the installation is indoors or out.
Click to expand...
This is outdoors. It is a fixed pier in salt water and these are shore tie feeders with GFP. There is also a ladder type cable tray in the trench but for whatever reason the installer chose to use j-hooks. 2014 code cycle I believe was enforceable when installed.

Does NEC recognize J-hooks using any other term than "cable routing assembly"?
 
Last edited:
jimdavis said:
I believe 300.3(A) would require individual THWN-2 conductors to be installed in a chapter 3 wiring method.
Click to expand...

Bingo. And I can't imagine how incredibly difficult it would be to pull any amount of THHN in a concrete trench without damaging the insulation somewhere along the lines. Apparently whoever installed this didn't imagine either. Or know a very basic code that is literally on the front page of chapter 3 installations. how it ever passed and inspection is beyond me
 
How do the cables look? I would think pulling/dragging them in a concrete trench would tear up the insulation pretty bad. I too agree that 300.3 definitely apply's to THWN, and J-hooks are not listed in that section.
 
We regularly have the concrete guys form troughs in the floor the an integrated housekeeping pad for MCC's. We find most MCC's don't have enough room at the bottom to chase wiring through so this is what we've done many times in the past. We don't use any hangers in the trough, we just lay the conductors on the bottom. When we do vaults or similar we'll use nonmetallic d-rings to hold the smaller conductors up and out of the way of the larger conductors that may damage them during installation.

I've honestly never checked code for our troughs or d-rings, I was just using common sense. But, if you want to hang an energized wire on a metal strap or j-hook, I'd wager it most likely needs to be bonded to an EGC. Which opens a whole 'nother can of worms on how you would even do that. Easier to use nonmetallic.

Here's a pic of a trough for an MCC:
 

Attachments

  • 202.jpg
    202.jpg
    157.6 KB · Views: 3
Status
Not open for further replies.
Top