Class 2 Wiring 70V -- Loudspeakers

[jfragola]

Just a little question regarding class 2 wiring. When does class 2 wiring need to be in conduit for loudspeakers? This is for a commercial installation, above a drop ceiling. It's a 70V class 2 system. I'm trying to determine if it needs to be in conduit at all. From what I get out of Art. 725, it doesn't. When do chapter 3 wiring methods come into play ? Any insight would be appreciated ! Thanks !

 

[Dennis Alwon]

Just a little question regarding class 2 wiring. When does class 2 wiring need to be in conduit for loudspeakers? This is for a commercial installation, above a drop ceiling. It's a 70V class 2 system. I'm trying to determine if it needs to be in conduit at all. From what I get out of Art. 725, it doesn't. When do chapter 3 wiring methods come into play ? Any insight would be appreciated ! Thanks !

Is the ceiling a plenum?

 

[jfragola]

no plenum ceiling.

 

[zbang]

My understanding is that 725 trumps the 300's. FWIW, I don't think I've ever seen 70v speaker lines in pipe unless it was a plenum and nobody felt like using planum-rated cable. Strike that, I have seen it in pipe a few times, but the cable would come out of a box, if there was a box at all, and drop to the ceiling speaker. I think all of those places were new construction and paging system pipe was roughed in at the same time as everything else.

 

[hbiss]

Class 2 is all you need to know. They invented the "class" system so you don't have to guess what wiring method is required from voltage, current and protection. That's all been done. So, if it says Class 2 wiring on an amplifier you can use any CL2 or better wiring method.

CL2 is the lowest in the hierarchy followed by CL3 then class 1. All are covered by Art 725 or 800 on. The "front of the book" does not apply to 725 and 800 on unless it specifically refers you to an article there. So Chapter 3 wiring methods would not apply unless an article in 725 or 800 on says so.

-Hal

 

[don_resqcapt19]

Hal,

The "front of the book" does not apply to 725 and 800 on unless it specifically refers you to an article there.

I don't agree. Chapters 1 though 4 apply to Article 725 unless amended by Article 725. Chapter 8 stands alone and only rules in Chapters 1 through 4 that are specifically called out in Article 800 apply.

90.3 ... Chapters 1 through 4 apply except as amended by Chapters 5, 6, and 7 for the particular conditions.
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.

Don

 

[Pierre C Belarge]

Take a peak at 725.3.

 

[hbiss]

Chapters 1 through 4 apply except as amended by Chapters 5, 6, and 7...

Then we go to 725.3 to see how 90.3 is ammended for Chapter 7.

-Hal

 

[don_resqcapt19]

Hal,

Then we go to 725.3 to see how 90.3 is ammended for Chapter 7.

That only takes out the rules in Article 300. The rest of the rules in chapters 1-4 still apply to Article 725 installations.

725.3 Other Articles
Circuits and equipment shall comply with the articles or sections listed in 725.3(A) through 725.3(G). Only those sections of Article 300 referenced in this article shall apply to Class 1, Class 2, and Class 3 circuits.

If you are saying that the first sentence is an exemption to all of the other rules in chapters 1 through 4, then I don't agree. I would agree if that sentence used the word "only" or other similar wording, but as it is not written it doesn't have any real meaning or purpose.
Don

 

[hbiss]

Actually Don, after reading it a few times I have to agree with you. 725.3 only ammends Chapter 3.

-Hal

 

[ryan_618]

To answer teh question, Class 2 cable never needs to be in a conduit. There are times that it might have to be plenum rated or riser rated. There are also very, very rare instances that it must be reclassified as Class 1 (which requires conduit or other chapter 3 wiring methods), but it never has to be in a raceway. See 725.52.

 

[ryan_618]

Actually Don, after reading it a few times I have to agree with you. 725.3 only ammends Chapter 3.

-Hal

It amends anything in Chapters 1-4. It eliminates Article 300, save for a few specific rules.

 

[don_resqcapt19]

Ryan,

It amends anything in Chapters 1-4. It eliminates Article 300, save for a few specific rules.

Are you saying that only the sections listed in 725.3 apply to Article 725 installations?
Don

 

[ryan_618]

Don, no. I am saying that everything in chapters 1-4 can be modified by Article 725. If Article 725 makes no such modification, the rule in 1-4 applies.

For example, 725 doesn't modify how you install EMT, so the EMT rules apply. If 725 said that only compression EMT couplings were allowed for Class 1 nonpower limited circuits , then only compression couplings would be allowed.

I am just trying to clear up the way 90.3 works, since it seems to be the major issue in this thread.

 

[don_resqcapt19]

Ryan,

Don, no. I am saying that everything in chapters 1-4 can be modified by Article 725. If Article 725 makes no such modification, the rule in 1-4 applies.

I agree with that, but the issue to me is the meaning of the first sentence in 725.3. I don't think that it really means anything, but I can see how it can be read to say that only the articles and sections listed in 725.3 apply to Article 725 installations.

Circuits and equipment shall comply with the articles or sections listed in 725.3(A) through 725.3(G). Only those sections of Article 300 referenced in this article shall apply to Class 1, Class 2, and Class 3 circuits.

Why is that first sentence in the section?
Don

 

[jfragola]

To answer teh question, Class 2 cable never needs to be in a conduit. There are times that it might have to be plenum rated or riser rated. There are also very, very rare instances that it must be reclassified as Class 1 (which requires conduit or other chapter 3 wiring methods), but it never has to be in a raceway. See 725.52.

Thanks for the info Ryan and everyone else. I didn't think it needed to run in conduit, but just figured might be good to hear a second opinion.

Why does 725.21 define max volts and VA for class 1, but no definition of max volts and VA for class 2 or 3 ? Also, what is the difference between 2 and 3 ?

 

[Pierre C Belarge]

Take a look at 725.41(A)FPN No. 2

Keep in mind, that most Class 2 power sources will label/list the items of interest you are looking for on the equipment itself.

 

[jfragola]

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Thanks for the info. I never new there was anything useful back there