Terminating Plenum IT Cables in Plenum Space

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maxbillington

Elec Engineer, Adjunct Faculty
Location
Colorado
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Prof Engineer
I have a school installation in which the contractor has terminated plenum rated IT system cables to plastic connectors within the plenum. The connectors mount on a video projector mounting plate that faces down into the room. The contractor did not use a back box to enclose the terminations.

I have pointed out the following code paragraphs:

The NEC 300.22 Wiring in Ducts, Plenums, and Other Air-Handling Spaces requires all cables installed in a plenum space to be in raceways, or plenum rated cable.

Article 300.15 Boxes, Conduit Bodies, or Fittings ? Where Required. "... a box or conduit body shall be installed at each conductor splice point, outlet point, switch point, junction point, termination point..."

The contractor's response is that Article 300 does not apply to communications cables.

So here is my question:

Are IT cable terminations in a plenum required to be within a box?
 
Is this really a plenum space, or an "other space used for environmental air" such as the space above a drop ceiling when used for return air?
 
The space is above the ceiling tiles

The space is above the ceiling tiles

The cables are terminated above the ceiling tile within the return air plenum.
 
You should have the contractor read Article 300.1 Scope:
"(A) All Wiring Installations
This article covers wiring methods for all wiring installations unless modified by other articles."

Article 800.53(A) makes things even MORE clear:
"Cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CMP. Abandoned cables shall not be permitted to remain. Types CMP, CMR, CMG, CM, and CMX and communications wire installed IN COMPLIANCE WITH 300.22 shall be permitted. Listed plenum communications raceways shall be permitted to be installed in ducts and plenums AS DESCRIBED IN 300.22(B) AND IN OTHER SPACES USED FOR ENVIRONMENTAL AIR AS DESCRIBED IN 300.22(C)."

So.......the bottom line is that Article 300 DOES apply to low voltage wiring.
 
Max,
The contractor's response is that Article 300 does not apply to communications cables.
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Have the contractor take a look at 725.3(C).
(C) Ducts, Plenums, and Other Air-Handling Spaces Class 1, Class 2, and Class 3 circuits installed in ducts, plenums, or other space used for environmental air shall comply with 300.22. Type CL2P or CL3P cables and plenum signaling raceways shall be permitted for Class 2 and Class 3 circuits installed in other spaces used for environmental air.
Click to expand...
The area in question is not a "plenum" per the NEC. It is "other space used for envriomental air". 300.22(C)(2) requires that equipment be in a metal enclosure or in a non-metallic enclosure listed for the purpose. Per the definition of equipment in Article 100, the device at the end of the cable is equipment and will require a box.
Don
 
Ear,
You should have the contractor read Article 300.1 Scope:
"(A) All Wiring Installations
This article covers wiring methods for all wiring installations unless modified by other articles."
Click to expand...
You can't use the Article 300 scope statement to make the rules in that article apply to Chaper 8 installations. The rule that governs the application of Article 300 to Chapter 8 installations is found in 90.3.
90.3 ... Chapter 8 covers communications systems and is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8.
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In this case the result is the same as the rule in Article 800 says you must apply the rules in 300.22. Also many code experts and the NEC handbook apply Article 725 to IT wiring systems and not Article 800. The Chapter 7 articles are not treated exactly the same as the Chaper 8 Articles per 90.3.
90.3 ... Chapters 1 through 4 apply except as amended by Chapters 5, 6, and 7 for the particular conditions.
Click to expand...
725.3 says "only those sections of Article 300 referenced in this article shall apply to Class 1, Class 2, and Class 3 circuits."
However, again the result is the same as 725.3(C) requires compliance with 300.22.
Don
 
ear,
Well, that was a roundabout way of saying, "OK".
Click to expand...
My real point was that you have to look at 90.3 to find out what rules apply for Chapters 5 through 8. You can't look at the scope in a Chapter 1 through 4 article to find that information.
Don
 
You have all been very helpful. You have generally traced my own search. What I am concluding is that the code does not expressly require terminations in "Other Air-Handling Spaces " be located within a box or enclosure. The code sections are quite specific about types of cables and types of raceway; but there is no hard statement about terminations and enclosing them.

Article 300.21 "Spread of Fire or Products of Combustion." states: "Electrical installations in hollow spaces, vertical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased."

It looks like this is as close as the code gets to saying "put terminations for IT systems in a box."
 
Max,
300.22(C)(2) requires the enclosure. The termination device is "equipment" and only equipment "with a metal enclosure, or with a nonmetallic enclosure listed for the use..." is permitted in the "other space used for envriomental air". If the equipment does not have an enclosure it is not permitted in the space.
Don
 
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