Wires in drop ceilings

[thelockdude]

Hi, I'm wondering if anyone can clarify 3 codes for me (commercial applications):
1. In drop ceilings, I'm not allowed to lay my wires on the ceiling tiles? They have to be fastened to the roof structure?
2. When running wire between floors, the wire has to go through a sleeve, and not just through the hole drilled into the floor? Of course I would use fire caulk either way.
3. All wire must be enclosed in conduit or something similar, to a height of 7'? I.e. no exposed low voltage wire? Even in a telephone room or hvac room?

Thanks.
Dan

 

[iwire]

Re: Wires in drop ceilings

1. In drop ceilings, I'm not allowed to lay my wires on the ceiling tiles? They have to be fastened to the roof structure?

This is an NEC requirement.

300.11(A)(1) or (2) for chapter 3 wiring methods

Or if not Chapter 3 wiring it may be covered by 800.5

2. When running wire between floors, the wire has to go through a sleeve, and not just through the hole drilled into the floor? Of course I would use fire caulk either way.

As far as the NEC that depends on the location and the wiring type.

There may be fire codes that require the sleeve.

3. All wire must be enclosed in conduit or something similar, to a height of 7'? I.e. no exposed low voltage wire? Even in a telephone room or hvac room?

Not an NEC rule inside buildings but I hear that many inspectors consider any wiring below 7' or 8' subject to physical damage and if that prohibits NM from being used down low.

Now do not forget that a job contract can specify all of the above and local amendments to the NEC are common.

 

[thelockdude]

Thank you, Bob, for the quick reply.

My NEC is 1996 - I ordered a new one as soon as this came up earlier this week, but in the mean time, I pored over my 1996 version.

I didn't think article 300 applied to the wiring I'm doing because of 300-1a, exception #2. I mainly looked towards 725.

These questions are concerning a specific job: I'm installing an access control system in a 6-story commercial / professional building. It's a plenum ceiling, so I used plenum cable throughout, but I just layed it on the tiles.

When I drilled through the floor, I firecaulked it, and wire-tied my cables neatly next to all the other cables which were run in the same manner.

Article 725-3b sends you back to 300-22. In reading 300-22c further, I don't see any mention of plenum rated cable as being an acceptable wire type in plenum ceilings (at least in my 1996 book) - so why do they make plenum cable?
Dan

 

[George Stolz]

Not an NEC rule inside buildings but I hear that many inspectors consider any wiring below 7' or 8' subject to physical damage and if that prohibits NM from being used down low.

I think he's referring to Cat-5 & RG-6 runs inside a drywalled wall. In the little commercial I've done, we installed EMT to above the dropped ceiling, where it exits the wall. After that, the cables were run in the scissors over the dropped ceiling.

I figured it was for future changes, at the time. It's easier to fish into a box if it's got a conduit to it, I figured that was all there was to it, but I didn't think to ask "why."

As for the fire-caulked sleeve, I've seen it and done it, because it's what I was told to do. Fire codes are something that elude me. :?

 

[hbiss]

I don't see any mention of plenum rated cable as being an acceptable wire type in plenum ceilings (at least in my 1996 book) - so why do they make plenum cable?

I don't have a 96 book here but isn't there a table in article 725 called "Cable Uses and Permitted Substitutions"? On those pages there also should be a description of general use, riser and plenum cables.

You won't find any reference to plenum rated cable in Chapter 3 because Chapter 3 mainly pertains to Class 1 wiring methods. There is no need for a plenum rated Class 1 wiring method since it's handled in other ways such as raceway or armored cables.

By the way, Chapter 3 only relates to your work if Article 725 or the Articles from 800 on specifically refer you back there.

Also, while it is a good idea to have the current 2005 code for reference, your jurisdiction most likely is using an older version. Might even be that the 1996 is the one in use. Check with your electrical inspector.

-Hal

 

[thelockdude]

Ok, thanks Hal. You've sort of confirmed what I thought re: the 1996 NEC: article 300 does not apply to me (strictly class 2 wiring) unless specifically referenced in article 725. I am getting a new 2005 NEC b/c I *think* in the newer book, MORE portions of article 300 apply to class 2 wiring. But I have not actually seen a new book yet, so I have not been able to confirm this.

Dan

 

[hbiss]

You've sort of confirmed what I thought re: the 1996 NEC: article 300 does not apply to me (strictly class 2 wiring) unless specifically referenced in article 725.

Read the front of the book.

I am getting a new 2005 NEC b/c I *think* in the newer book, MORE portions of article 300 apply to class 2 wiring. But I have not actually seen a new book yet, so I have not been able to confirm this.

Well you can read it here and see for yourself. I don't see any changes that way.

http://www.nfpa.org/freecodes/free_access_agreement.asp?id=7005SB

Also, like I said above the 2005 code has probably not been adopted where you are so it may make interesting reading but won't be useful to you.

You NEED to refer to the code that has been adopted by your jurisdiction. It's quite possible that some things in the new 2005 code could get you in trouble.

-Hal

 

[ed downey]

Regarding item #2: no you do not need a sleeve unless it is a local building code issue or a specification issue (Many specs require sleeves). The UL Fire resistance directory specifically shows many penetrations that are not sleeved. I have used 3M products for years without the use of sleeves.
-Ed

 

[iwire]

Regarding item #2: no you do not need a sleeve unless it is a local building code issue or a specification issue

Ed as I mentioned the NEC does require sleeves in some instances.

334.15(B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, listed surface metal or nonmetallic raceway, or other means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, listed surface metal or nonmetallic raceway, or other metal pipe extending at least 150 mm (6 in.) above the floor.

This applies to exposed runs of NM and has to do with physical damage not fire stopping.[/quote]

 

[RUWired]

Dan,Check out (2005) 760.3(A).It refers you to 300.21 Which requires you to fire proof between floors and walls.Also there are multiple articles in 760 that are pertaining to the 7' rule when passing through a floor.(760.30(A)(2)-760.52(B)(2)Typically,when fire proofing through fire rated walls and floors,only steel wiring methods are allowed to be fire proofed without a sleeve.If you are running cable ,including mc/ac/fa,then it requires a sleeve.This requirement is either nfpa or manufactures instructions.Plenum cable is to be used where ceilings are being used as a return to the ventilation system,760.61(A).
Rick

 

[thelockdude]

My work is access control. I have been referring to article 725. Do I need to refer to article 760 also, even if I'm not doing fire alarms?
Dan

 

[RUWired]

Dan,The same applies to 725 class 1-2-3 circuits,except for the 7' rule.I had f/a circuits in my mind from talking to another person in the field today.Article 725.8 mechanical execution of work describes keeping your work supported by straps hanger etc. 725.58 refers you to 300.11(B)(2) for suspended ceilings.Fire stopping is 725.3(B).It refers you to 300.21.Plenum and riser cables are still required where applicable.If your running through a fire rated wall,floor or plenum space, you need to use a sleeve properly sized for your cables and then fire proof inside and outside of the sleeve.
Rick

 

[Pierre C Belarge]

Dan,The same applies to 725 class 1-2-3 circuits,except for the 7' rule.I had f/a circuits in my mind from talking to another person in the field today.Article 725.8 mechanical execution of work describes keeping your work supported by straps hanger etc. 725.58 refers you to 300.11(B)(2) for suspended ceilings.Fire stopping is 725.3(B).It refers you to 300.21.Plenum and riser cables are still required where applicable.If your running through a fire rated wall,floor or plenum space, you need to use a sleeve properly sized for your cables and then fire proof inside and outside of the sleeve.
Rick

That is not what it says. One has to maintain the fire integrity when passing through a fire rated assembly. The different manufacturers have products that permit the wiring method to be installed directly without a sleeve, using the proper fire stopping.


The sleeve requirement is for locations that require protection for physical damage. There are many fire rated assemblies that can be penetrated that do not pose a danger from physical damage.

 

[RUWired]

Pierre, Firestopping without the use of a sleeve is ok where the firestopping is an approved method.I have'nt seen any thing other than blankets and bricks on cable trays that have have been an approved system.Not to say there are not other items.In all the buildings that i have work on and done, sleeves were the only approved method when going through a floor or fire rated wall when using cables.
According to nfpa [5000;8.8.2] penetrations shall be protected by a fire stop system or device.
[8.8.2.1] shall be in accordance with astm,e814 or ansi/ul 1479
[8.8.2.2.1]alternative requirements include,
(1)Rated assembly
(2)Enclosed in a shaft
(3)Concreted or grout
(4)where used with the following
(A) Steel cables
(B) Cables with steel jackets
(C) Cast or steel pipe
(D) Steel conduits
I believe nfpa 221 refers to this article as well.I am only giving my input based on what i have had approved and currently perform.
Rick

 

[RUWired]

I went on both 3m and hilti firestop systems web sites and found they have a great deal of information pertaining to just about any type of application,Except hilti did'nt have much in the line of floor penetration, mostly wall.Most of the single nometallic cables had to have the pvc or xlpe jacket.The mc/ac cables had to have pvc insulation and jacket which i did'nt understand.I think most jacketed nm cables are of the pvc type,and most of the zip cords are not.3m had the most floor penetrations with out sleeves.But article 725.61(B)(1)-(2)requires a listed raceway between floors.
(B) Riser Cables installed in risers shall be as described in any of (B)(1), (B)(2), or (B)(3):
(1) Cables installed in vertical runs and penetrating more than one floor, or cables installed in vertical runs in a shaft, shall be Type CL2R or CL3R. Floor penetrations requiring Type CL2R or CL3R shall contain only cables suitable for riser or plenum use. Listed riser signaling raceways shall be permitted to be installed in vertical riser runs in a shaft from floor to floor. Only Type CL2R, CL3R, CL2P, or CL3P cables shall be permitted to be installed in these raceways.
(2) Other cables as covered in Table 725.61 and other listed wiring methods as covered in Chapter 3 shall be installed in metal raceways, or located in a fireproof shaft having firestops at each floor.
Rick

 

[tkb]

Re: Wires in drop ceilings

1. In drop ceilings, I'm not allowed to lay my wires on the ceiling tiles? They have to be fastened to the roof structure?

This is an NEC requirement.

300.11(A)(1) or (2) for chapter 3 wiring methods

Or if not Chapter 3 wiring it may be covered by 800.5

Why do the manufactures of the gopher poles, fish sticks and the fishing reel on a gun show in their advertisments that you can open a ceiling tile and fish a wire and lay it on a suspended ceiling?
They make it like it is a legal way to install cables.

 

[iwire]

Re: Wires in drop ceilings

Why do the manufactures of the gopher poles, fish sticks and the fishing reel on a gun show in their advertisments that you can open a ceiling tile and fish a wire and lay it on a suspended ceiling?
They make it like it is a legal way to install cables.

Because they sell more that way. :wink: