Class 2 Separation from Power

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jes25

Senior Member
Location
Midwest
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Electrician
Based on the NEC language below, it seems I can put a typical Cat6 cable in a wireway with power THHN conductors. I say this because a Cat6 cable meets the definition of a nonmetallic-sheathed cable: "A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket."

That said, my interpretation feels wrong. I would love to hear your thoughts on if you think the NEC allows this.

From 725.136(I)1 2023 NEC:
"Conductors of Class 2 circuits shall be separated by at least (2 in.) from conductors of any electric light, power, Class 1, non-power-limited fire alarm, or medium-power network-powered broadband communications circuits unless one of the following conditions is met:

(1) Either all of the electric light, power, Class 1, non-power-limited fire alarm, and medium-power network-powered broadband communications circuit conductors or all of the Class 2 and Class 3 circuit conductors are in a raceway or in metal-sheathed, metal-clad, nonmetallic-sheathed, Type TC, or Type UF cables."
 
725.136 ·Separation from Electric Light, Power, Clas 1, Non-Power-Limited Fare Alarm Circuit
Conductors, and Medium-Power Network-Powered Broadband Communications Cables.

(A) General. Cables and conductors of Class 2 and Class 3 circuits shall not be placed in
any cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar
fitting with conductors of electric light, power, Class 1...

-Hal
 
For sure. But non-metallic sheath cable type NM, and non-metallic sheath cable are separate and have separate definitions in 100.
 
I mean I know I can't/shouldn't do what I said in the OP but the language seems to indicate I can. Do you think a PI is appropriate here? Never done one before.
 
jes25 said:
Okay, but Do you agree the language contradicts itself based on the definition of non-metallic sheathed cable?
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It would first help if they had a definition for "non-metallic sheathed cable". I would suggest "chapter 1 conductors factory assembled and enclosed in a flexible PVC or other non-conductive outer jacket".

-Hal
 
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jes25 said:
I say this because a Cat6 cable meets the definition of a nonmetallic-sheathed cable: "A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket."
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Using this logic SO cord is also a nonmetallic-sheathed cable.
 
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jim dungar said:
Yes, there are different rules for NM(B), Flexible cables, and Class 2 cables even though they have a common generic construction.
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And the rules for those class 2 cables use generic construction language "metal-sheathed, metal-clad, nonmetallic-sheathed". Very poorly written IMO
 
Part (B) is also kind of nebulous: Separated by Barriers. Class 2 and Class 3 circuits shall be permitted to be installed together with the conductors of electric light, power, Class 1 , non-power-limited fire alarm, and medium-power network-powered broadband communications circuits where they are separated by a barrier.

So what is a barrier? is the cable jacket a barrier? Can you bundle all the CL2/CL3 cables and sleeve them and you have a barrier? Does it need to be a firm plastic or metal shield to be a barrier?
 
jes25 said:
For sure. But non-metallic sheath cable type NM, and non-metallic sheath cable are separate and have separate definitions in 100.
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I think you mean Article 334.

It's weird because every other wiring method article covers only one type, except for 338, which makes clear that Service Entrance Cable is only of the two types (SE and USE). I think it an editing oversight and the intention is for 'nonmetallic-sheathed cable' to refer only to the listed NM and NMC types.
 
jaggedben said:
I think you mean Article 334.

It's weird because every other wiring method article covers only one type, except for 338, which makes clear that Service Entrance Cable is only of the two types (SE and USE). I think it an editing oversight and the intention is for 'nonmetallic-sheathed cable' to refer only to the listed NM and NMC types.
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Thanks, and I agree with your take on 338.

But in my earlier post I was trying to point out the code definitions differentiate between Nonmettallic Sheath Type NM cable, and Nonmettallic Sheath cable. See below.


Cable, Nonmetallic-Sheathed.
A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket. (CMP-6)

Cable, Nonmetallic-Sheathed (Type NM).
Insulated conductors enclosed within an overall nonmetallic jacket. (CMP-6)
 
jes25 said:
Cable, Nonmetallic-Sheathed.
A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket. (CMP-6)
Click to expand...
This requires all conductors, in the cable, to be insulated.

jes25 said:
Cable, Nonmetallic-Sheathed (Type NM).
Insulated conductors enclosed within an overall nonmetallic jacket. (CMP-6)
Click to expand...
While this allows at least 1 conductor in the cable to be uninsulated, like a bare ground.
 
jes25 said:
Thanks, and I agree with your take on 338.

But in my earlier post I was trying to point out the code definitions differentiate between Nonmettallic Sheath Type NM cable, and Nonmettallic Sheath cable. See below.


Cable, Nonmetallic-Sheathed.
A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket. (CMP-6)

Cable, Nonmetallic-Sheathed (Type NM).
Insulated conductors enclosed within an overall nonmetallic jacket. (CMP-6)
Click to expand...

Yeah I get what you are saying, and I'm saying I *think* that's not intended. The first definition isn't supposed to refer to anything not included in the second two definitions.

If you're intention is to fix this with a PI, then either formulate the definitions in 334 like the one in 338, or change 'Nonmetallic-Sheathed Cable to 'Type NM or NMC cable' in 725.
 
@jes25 you bring up some good points about the duplicate definitions, that may be prohibited by the NEC style manual,
Your PI should reference NEC Style Manual 2023 v2, 2.1.2.7 Terms with Multiple Definitions:
Terms with Multiple Definitions. If two or more definitions exist for a term in Article 100, a
task group shall be formed to work on the development of a single definition. If this cannot be
accomplished, another term shall be selected or the term shall be identified in the context of the
specific application
Click to expand...

Contrary to popular belief the NEC does not automatically follow its own style manual.
The communications sections of NEC is hard to work on, you tweak on thing and others fall apart. For example the 2023 NEC Panel 3 tried to rework the low voltage part of the code and ended up making some big mistakes, like accidentally deleting the Class 1 nonpower-limited section I use often. Fortunately no inspectors noticed, and NFPA issued a TIA (1688) to fix the now 2023 300.26.

My take on the NEC is that the NEC is permissive, something is allowed unless its expressly prohibited.
The NEC has to expressly say dont put class2 cables in conduit with THHN or something to that effect.
Now in the 2026 NEC (that you would make PI on) I *think* the section you speak of moved to 722.133.
At first glance this 2026 722.133 (A) is a strange re-write in permissive language after note really really prohibiting anything. I don't have link so I cant easily post the 2026 section.
 
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