25 pair outdoor cable into plenum ceiling

captstent

Member
Is it code we have installed a 25 pair under ground phone cable into a building, then goes into plenum rated innerduct conduit, if part of the space the cable goes through in the building is a return air ceiling?
Also did not know if a company makes a cable that is rated for direct burial and plenum at the same time or if the plenum rated innerduct would be sufficient.
 

Silversam

Member
Location
NYC
Well steel conduit would have been better, but - depending on local ordinances - plenum innerduct should work.

No one I know of makes a combination outdoor and plenum cable.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Well steel conduit would have been better, but - depending on local ordinances - plenum innerduct should work.

No one I know of makes a combination outdoor and plenum cable.
The NEC does not permit the use of non-plenum rated cables in a plenum rated innerduct, that is installed in a 300.22(C) space, unless that innerduct is installed in one of the raceways listed in 300.22(C)(1).
300.22(C)(1) ... Other types of cables, conductors, and raceways shall be permitted to be installed in electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, rigid metal conduit without an overall nonmetallic covering, flexible metal conduit, or, where accessible, surface metal raceway or metal wireway with metal covers.
Both the cable and the innerduct are "other types" as those items are not specifically permitted in the proceeding part of that section.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
You don't want to run OSP cable for any distance anywhere within a building, especially filled (underground) cable. The compound is flammable aside from the fact that the cable has no listing. The practice is to transition to a suitable cable, in your case 25 pair CMP within a few feet of the point of entrance. This should be done within a suitable splice case. Normally you would also install protectors at that location anyway and there are protector "housings" that will provide the transition.

-Hal
 
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luckylerado

Senior Member
Is it code we have installed a 25 pair under ground phone cable into a building, then goes into plenum rated innerduct conduit, if part of the space the cable goes through in the building is a return air ceiling?
Also did not know if a company makes a cable that is rated for direct burial and plenum at the same time or if the plenum rated innerduct would be sufficient.
OSP cable entering a building is limited to 50' from the point of entrance, and is typically required to terminated at a listed protector device as close to the point of entrance as practical.

There are products our there that are both plenum rated and underground rated. Very Very expensive. We use it when going from a basket tray to say a floor box in a slab. CommScope, and VersaLan are two products that come to mind.

Best bet is to install a protector block and change to a cable that is listed for the use.
 

vancouvertech

Member
Location
vancouver
You guys can correct me if I am wrong on 25 pair direct bural cable

You guys can correct me if I am wrong on 25 pair direct bural cable

The cable that I have often see punched down, and done one my self, and terminated at least 50-100 25pair extension in buildings. coming out of conduit that leads to the street is 25pair gell filled cable. I imagine this is also called direct burial cable. If the cable passes between two buildings then circuit protection if not advisable is required in the event of a cloud to ground lighting strike for added protection.
 

grich

Senior Member
You don't want to run OSP cable for any distance anywhere within a building, especially filled (underground) cable. The compound is flammable aside from the fact that the cable has no listing. The practice is to transition to a suitable cable, in your case 25 pair CMP within a few feet of the point of entrance. This should be done within a suitable splice case. Normally you would also install protectors at that location anyway and there are protector "housings" that will provide the transition.

-Hal
That is exactly how the building I'm in now was connected 30 years ago by NW Bell. OSP cable comes in the phone room to a splice case, and NM flexes come out the other end containing the binders going to the protectors.
 
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