Flexible cord through wall

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jtinge

jtinge

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Hampton, VA
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Sr. Elec. Engr
In industrial locations, it is not uncommon to see prefabricated flexible cables routed through enclosure walls using a Roxtec cable pass through or something similar. In light of NEC 400.12 (2), how is this code compliant?
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jtinge said:
In industrial locations, it is not uncommon to see prefabricated flexible cables routed through enclosure walls using a Roxtec cable pass through or something similar. In light of NEC 400.12 (2), how is this code compliant?
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Because on a machine, the NEC doesn't apply; it's (maybe) a UL508A issue. Those glands are intended to be used to get multiple cables / hoses out of industrial control enclosures and into wire tray / onto the machine's frame.

I can also see them being used to isolate cables as they pass into "clean room" areas, for instance; they're very good at that. "Engineering supervision" solves a lot.

Roxtec -type gland plates are used extensively in marine environments, along with flexible cables. Sealing from (salt)water ingress and fire spread are extremely important on ships. Conduit isn't used, as water can pass through the interior of the conduit and cause damage.



SceneryDriver
 
SceneryDriver said:
Because on a machine, the NEC doesn't apply; it's (maybe) a UL508A issue. Those glands are intended to be used to get multiple cables / hoses out of industrial control enclosures and into wire tray / onto the machine's frame.

I can also see them being used to isolate cables as they pass into "clean room" areas, for instance; they're very good at that. "Engineering supervision" solves a lot.

Roxtec -type gland plates are used extensively in marine environments, along with flexible cables. Sealing from (salt)water ingress and fire spread are extremely important on ships. Conduit isn't used, as water can pass through the interior of the conduit and cause damage.



SceneryDriver
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The application at our site, that is the basis for my inquiry, is for transitioning cables from a utility corridor to the inside of a clean room between two pieces of equipment. I have used Roxtec in the past to route instrumentation cables into a wind tunnel test section, but admittedly never thought about how the 400.12 (2) requirement may or may not apply. It would be nice to see an exception that explicitly permitted the use of assemblies for specifically designed for routing flexible cables in bulkheads or walls in supervised installations.
 
jtinge said:
The application at our site, that is the basis for my inquiry, is for transitioning cables from a utility corridor to the inside of a clean room between two pieces of equipment. I have used Roxtec in the past to route instrumentation cables into a wind tunnel test section, but admittedly never thought about how the 400.12 (2) requirement may or may not apply. It would be nice to see an exception that explicitly permitted the use of assemblies for specifically designed for routing flexible cables in bulkheads or walls in supervised installations.
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I believe that might be covered under "engineering supervision." Practically, there are sometimes design situations that need some common sense. I think a clean room application would be one of those. I always read that section as prohibiting some hillbilly from dragging SO cable through the studs of his shack and powering his toaster.


SceneryDriver
 
Guess I'm wondering if "where run through holes in walls, structural ceilings...." was intended to apply to cable transit systems or only to a drilled hole? Wondering what the discussion of the committee was when this prohibition was included.
 
Not all 'flexible cables' are subject to article 400, in particular power, control, and instrumentation tray cables are covered under their own articles.
 
jtinge said:
Guess I'm wondering if "where run through holes in walls, structural ceilings...." was intended to apply to cable transit systems or only to a drilled hole?
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Wouldn't matter. You can't get from one side to the other without a hole. A "cable transit system" is just a fancy hole...

-Hal
 
So if the picture shown in the OP was on a clean room wall and the cables were SO type cables, that would be a non compliant installation due to the restrictions of 400.12 (2), but if the cables were article 336 power and control tray cable, it might be okay in an industrial establishment with proper supervision and since it doesn't have the prohibition of not routing through a wall?
 
I work in cleanrooms that make semiconductors and don't allow the flexible cords carrying power to go through the structural walls or under raised floor panels. The cable jackets are not generally chemical resistant. We have yearly inspections and somewhere there is always a jacket falling apart. Going through walls or floors the cables are hidden and any damage concealed hence the prohibition in 400.12. Also some of the wall and under floor areas are classified as either "other space" or a plenum and those rules apply. Instrumentation cable is fine as long as it meets any other requirements.
 
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