Nec 725.154

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erickench

erickench

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Brooklyn, NY
This is a bit of an interpretation problem. The above section state's:

Listed plenum signaling raceways shall be permitted to be installed in other spaces used for for environmental air as described in 300.22(C).

Now if I look at section 300.22(C) the requirement seem's to list wiring methods that have an all metal exterior such as metal wireway and Type MC cable. But I do not see this in any of Mike Holt's illustrations. The raceway and the listed plenum use cable are run exposed in the environmental airspace. Does anyone have a clear interpretation of this rule?
 
If the raceway is a listed plenum raceway you can install it in "other spaces used for environmental air". Note that you still have to use a cable with a "plenum" listing when installing it in the listed plenum raceway. This is one brand of listed plenum raceway. Remember that the rules in Chapter 7 are permitted to modify those in Chapter 3 per 90.3.
 
But the reference to NEC 300.22(C) confuses things. Where do you see the words "plenum signaling raceway" in that section? One would think that the plenum raceway would be inside a wireway or something.
 
erickench said:
But the reference to NEC 300.22(C) confuses things. Where do you see the words "plenum signaling raceway" in that section? One would think that the plenum raceway would be inside a wireway or something.
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There is no need for a reference to "plenum signaling raceway" in 300.22(C) as its only use is for Article 725 applications. The only reason the reference in 725.154 is for the definition of "other space used for environmental air".
 
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Okay here's another problem. The section start's out with this sentence:

Cables installed in ducts, plenums, and other spaces for environmental air shall be Type CL2P or CL3P.

How is cable installed in a duct or plenum with out metal raceway you might ask. The next sentence follows:

Listed wires and cabling installed in compliance with 300.22 shall be permitted.

This is fine for running metal raceway inside a duct or plenum containing Type CL2P or CL3P cables. But why is it permitted and not required? And how does this apply to environmental air spaces? Metal raceway is not needed in this case.
 
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don_resqcapt19 said:
Note that you still have to use a cable with a "plenum" listing when installing it in the listed plenum raceway.
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Is that statement correct? I thought if a cable was in conduit inside a plenum area then the cable did not need to be plenum rated. Is THHN/THWN plenum rated?
 
dhalleron said:
Is that statement correct? I thought if a cable was in conduit inside a plenum area then the cable did not need to be plenum rated. Is THHN/THWN plenum rated?
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The statement is correct for the type of raceway we are talking about in this thread.
 
erickench said:
Okay here's another problem. The section start's out with this sentence:

Cables installed in ducts, plenums, and other spaces for environmental air shall be Type CL2P or CL3P.

How is cable installed in a duct or plenum with out metal raceway you might ask. The next sentence follows:

Listed wires and cabling installed in compliance with 300.22 shall be permitted.

This is fine for running metal raceway inside a duct or plenum containing Type CL2P or CL3P cables. But why is it permitted and not required? And how does this apply to environmental air spaces? Metal raceway is not needed in this case.
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I have no idea what you are asking. The only area where metal raceway is not required is 300.22(C). In general no wiring is permitted in a duct or plenum space. 300.22(B)
 
Wiring is permitted in a duct or plenum if used for sensing or direct action upon the contained air. But it must be in a metal raceway. All I'm saying is that this particular section of the NEC is not clear and I'm glad it's proposal time because I am gonna attempt to clear it up for everybody.
 
erickench said:
Wiring is permitted in a duct or plenum if used for sensing or direct action upon the contained air. But it must be in a metal raceway. All I'm saying is that this particular section of the NEC is not clear and I'm glad it's proposal time because I am gonna attempt to clear it up for everybody.
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I don't see anything in the two sections that you are talking about that is not clear. The rule in 725.154 does not interact with the rule in 300.22(B).
 
I agree with Don, just watch the video on the MH website on 300.22 and the section you refer to and 300.22 do not go together or at least that what was stated in the video...I also posted a question this morning about 300.22...
 
erickench said:
Where is the rule that state's that Type CL2P and CL3P cables must be installed in metal raceway when inside plenums and ducts?
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You find that in 300.22(B). No installation with an outer non-metallic covering is permitted in that application. 300.22(B) is not modified by any rule in Article 725 so it applies to Article 725 installations inside ducts or plenums.
 
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