Osp cable run inside building

[DEREK WHITBREAD]

I am trying to determine if NEC permits running OSP data cable in EMT conduit within a building if is is exposed less than 50 feet before terminating. We are installing data in floor boxes poured in a slab. The cables are in conduit all the way to the data closet and are terminated with-in 25 feet of where they leave the conduit. Since code requires wet area cable in conduit run under slab we need to run OSP cable that was specified and approved by the electrical engineer. The inspector first told use we could not run non cm rated cable in a building, and we explained the cable had to meet wet location requirements he said we would have to run it in rigid conduit. There are no protectors involved, so the only issue should be the fire rating of the jacket which should be addressed by placing it in an EMT raceway with compression connectors.

Help!

 

[don_resqcapt19]

I don't see any permission to install that cable within the building unless it terminates in an enclosure or on a primary protector. 800.48

 

[OTT2]

I am trying to determine if NEC permits running OSP data cable in EMT conduit within a building if is is exposed less than 50 feet before terminating. We are installing data in floor boxes poured in a slab. The cables are in conduit all the way to the data closet and are terminated with-in 25 feet of where they leave the conduit. Since code requires wet area cable in conduit run under slab we need to run OSP cable that was specified and approved by the electrical engineer. The inspector first told use we could not run non cm rated cable in a building, and we explained the cable had to meet wet location requirements he said we would have to run it in rigid conduit. There are no protectors involved, so the only issue should be the fire rating of the jacket which should be addressed by placing it in an EMT raceway with compression connectors.

Help!

Where does the code require a "wet location cable"?

Looks as if 800.154 list those cables permitted to be within the building.

Good luck!!

 

[DEREK WHITBREAD]

Since the wet location rule is fairly new it doesn't seem the NEC code has addressed all of the issues. A lot of the confusion comes from OSP nec code dealing with outside plant installations, not with the issue of OSP cable itself which is not rated. I would think the 310.10(c) exeption for communication cables under article 800 would allow the cable, non rate OSP marked, to be used in this application.



The problem Raceways and wet locations, NEC Sections 300.5(B) and 300.9
The inside of a conduit installed in a wet location is to be considered a wet location. This sounds redundant but many people believe the inside of a conduit should be considered a dry environment. The 2008 NEC Section 300.5(B) now clearly states that underground raceways are considered a wet location that require conductors rated for wet locations. The NEC has also added new wording to this section that helps to clarify that cables installed under a building shall be in a raceway, even if they are rated for direct burial.
Section 310.10(C) requires that cables in a wet location be listed for use in wet locations.
Underground Communications Cables Entering Buildings Section 800.47, which deals with separation requirements between communications cables and power cables, has a new statement that ?310.10(C) shall not apply to communications wires and cables?. Section 310.10(C) requires that cables in a wet location be listed for use in wet locations. What is the significance of this change? Under the provisions of section 90.3, Chapter 8 is independent of Chapters 1 through 7; section 310.10(C) does not apply to Article 800 unless it is specifically referenced, which it is not. The statement that 310.10(C) does not apply was added for emphasis since some inspectors are nonetheless demanding wet rated telephone cable. The telephone cable that enters buildings underground is unlisted outside plant cable. It is designed to be buried in the earth, but it can?t have a wet rating because it is unlisted.


plant applications.
Loose buffered cables are typically unlisted because of the filling compounds used within the cables. The NEC allows the use of exposed outside plant cable for the first 15m (50ft) at the building entrance. If the cable must run to a point farther away than 15m the most cost-effective solution may be to enclose the cable. Raceway, in accordance with Chapter 3 of the NEC, should be used for non-conductive cables. Rigid conduit, grounded in accordance with the NEC, should be used for conductive cables. Local building codes should be referred to for exact requirements.

This statement would indicate that the reason for requiring rigid conduit is a grounding issue due to the cables conductive characteristics. Since in most applications for Outside Plant (OSP) cable , the cable is originating external to the building (most commonly from a utility or a remote building) and is thus subject to induced current from lightning or other external sources. Code also requires surge protection on the cable, so the rigid conduit requirement may be required to help dissipate or contain the result of a large surge. Since the non conductive OSP fiber with the same jacket and flame characteristics as the conductive OSP cable can be installed in EMT conduit, that would indicate the EMT conduit would meet the flame spread requirement in the same way running non plenum rated cable through a plenum is allowed if it is installed a EMT raceway. The installed CAT6 cable has the same jacket composition as the non conductive fiber cable and it is all internal to the building structure so it is not subject induced current. I think the confusion on requirements is the NEC code addresses OSP cable as an outside plant installed cable, but in the West Park School application we are dealing with a non rated cable with an OSP marking that meets the wet area requirement for underground conduit installations and the EMT raceway system with less than 50 feet of exposed cable to the interior of the building meets the flame spread requirement listed in outside plant cable installation. In addition to meeting the 50 foot rule, all exposed cable is contained in a fire rated data closet which further protects against flame spread. Since the wet location requirement is relatively new, not all cable manufactures have addressed this problem, and there seems to be a lot of confusion on the issue.


Thank you ny input on this issue.

 

[OTT2]

You make some valid points. However there is NO requirement that communications cables have a "wet location" rating. If a inspector requires this there should be a code citation that he or she can quote. Otherwise it is simply not a requirement unless there is a state or local amendment to the adopted code.

Another thing to bear in mind is if this OSP cable has a smoke and or flame rating or test. It is simply not an option to install any cable because it is enclosed in a raceway or "fire rated assembly or construction."

Keep in mind the Purpose of this, see 90.1

 

[hbiss]

Loose buffered cables are typically unlisted because of the filling compounds used within the cables. The NEC allows the use of exposed outside plant cable for the first 15m (50ft) at the building entrance. If the cable must run to a point farther away than 15m the most cost-effective solution may be to enclose the cable. Raceway, in accordance with Chapter 3 of the NEC, should be used for non-conductive cables. Rigid conduit, grounded in accordance with the NEC, should be used for conductive cables. Local building codes should be referred to for exact requirements.

This statement would indicate that the reason for requiring rigid conduit is a grounding issue due to the cables conductive characteristics. Since in most applications for Outside Plant (OSP) cable , the cable is originating external to the building (most commonly from a utility or a remote building) and is thus subject to induced current from lightning or other external sources. Code also requires surge protection on the cable, so the rigid conduit requirement may be required to help dissipate or contain the result of a large surge. Since the non conductive OSP fiber with the same jacket and flame characteristics as the conductive OSP cable can be installed in EMT conduit, that would indicate the EMT conduit would meet the flame spread requirement in the same way running non plenum rated cable through a plenum is allowed if it is installed a EMT raceway. The installed CAT6 cable has the same jacket composition as the non conductive fiber cable and it is all internal to the building structure so it is not subject induced current. I think the confusion on requirements is the NEC code addresses OSP cable as an outside plant installed cable, but in the West Park School application we are dealing with a non rated cable with an OSP marking that meets the wet area requirement for underground conduit installations and the EMT raceway system with less than 50 feet of exposed cable to the interior of the building meets the flame spread requirement listed in outside plant cable installation. In addition to meeting the 50 foot rule, all exposed cable is contained in a fire rated data closet which further protects against flame spread. Since the wet location requirement is relatively new, not all cable manufactures have addressed this problem, and there seems to be a lot of confusion on the issue.

Where the heck are you getting this information from??

OSP cable is not unlisted because of the filling. Even unfilled cable is unlisted for the simple reason that there is no need for it to be listed. It's designed to be used outside of structures.

That said, not only would the filling of a filled cable be a problem with smoke and flame spread, the poly jacket used with both filled and unfilled cables would also. That's the reason for the NEC limit of 50' and if longer it must be run in a metallic raceway- to prevent it from burning and creating toxic smoke.

You also need to keep in mind that a conduit buried in the soil beneath a floor slab is considered outside of the building so PVC conduit is perfectly fine and is preferable for corrosion resistance. Also, I do agree that such a raceway is considered a wet location but the NEC couldn't care less what type of LV cable you run through it.

Another thing is that you are unclear as to the size of this cable. You mention data and CAT6. I think you throw fiber in there someplace also. CAT6 can be had in a listed filled cable and I can't see other than multiple runs of 4 pair in a floorbox system. Fiber is never flooded.

It sounds to me like some engineer with little knowledge is putting his 2 cents in here.


-Hal