Parallel 3/O THHN from tray to Panel entry

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Electroplaxes

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Nunica, MI
Industrial application, using parallel 3/O THHN for a 400A feed via cable tray. The question is in how to properly enter the panel...

I know Icotek and Roxtec have panel passthroughs capable of handling multiple conductors/cables in one housing but long lead times, pricey, and not as robust as I was hoping (rubber inserts sagging and twisting over time)

I was wondering if there is another way?

I want a robust application that seals the entry from dust and debris. I'm playing with the idea of running them through individual nylon cord grips. My concern is the metal between them, it creates the possible of picking up induced voltage like the core of a transformer. To remedy this I want to take a Carlon (UL listed) 2 gang cover and put cord grips in that. Knock out a 4" square hole and attached the plate to the panel. With all the parts being listed, is there any code restrictions to doing this?
 
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oldsparky52

Senior Member
Location
Wilmington, NC USA
Are you talking about each conductor through it's own cord grip or each cable (with multiple conductors) running through it's own cord grip?

Either way, I don't see how installing them in a metal plate is any different than installing them in the panel. Can you not cut a notch between entry holes?
 
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Electroplaxes

Member
Location
Nunica, MI
oldsparky52 said:
Are you talking about each conductor through it's own cord grip or each cable (with multiple conductors) running through it's own cord grip?

Either way, I don't see how installing them in a metal plate is any different than installing them in the panel. Can you not cut a notch between entry holes?
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Individual conductors through individual cord grips (not a multi-conductor cable)

Not a steel plate, a PVC or fiberglass plate.
 
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paulengr

Senior Member
Electroplaxes said:
I want to maintain a UL listing, that’s why I’m thinking a Carlon or Cantex FS cover made of thicker PVC. It’s already listed to cover electrical applications.
Click to expand...

Generally your cheapest option is using cable meant for trays: TC-ER, ITC, or MC. With TC you use CGBs for sealed terminations. You also must run conduit stubs from the tray to the box which answers your first question. The CGB is on the stub entry. This is the traditional method and not inexpensive.

With MC and ITC you use special fittings for armored cable which are not cheap but since it is armored as long as it’s supported every 3 feet, these can run directly from the enclosure to equipment. This reduces labor cost but the cable and fitting cost is so high stubs and TC are cheaper.

With TC-ER it has the crush/impact rating of MC but no armored jacket so a CGB is acceptable. So you run tray for neatness and support. At both ends though you drop out of the tray and land the cable without tray as long as it is supported every 3 feet. This can look a little jacked up but since it can run outside tray, no need for a lot of fittings with the tray either since Code allows spanning short gaps such as dropping out of a horizontal ladder onto another vertical tray mounted on a wall to enter a box.

Roxtec is a very expensive solution but where it shines is cable entries when there are molded plugs that can’t be field terminated like computer cables.



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