Data Cable Terminations Under Raised Access Floor

[ed downey]

I have an office building that we have a subcontractor installing Cat. 6 cables under the raised floor (The area under the raised floor in this office building is used for conditioned air movement). There are spare cables terminated under the raised floor for possible future needs.

Do these terminations need to occur in a box of some sort? I could not locate anything in Article 800. I am asking this because I heard through the grapevine that this is a NEC requirement but I could not locate in the code.

Any help would be appreciated.

-Ed

 

[JFletcher]

It looks like 800.3(B) could be the requirement, however Leviton (and certainly most other name-brand manufacturers) list their jacks as meeting the standards of article 800, so I would surmise that also means using them in air-handling spaces.

Why not terminate the cables on patch panels instead of below the floor?

 

[ed downey]

I talked to the engineer who designed the Data Distribution and he indicated he has seen some inspectors consider cables installed under raised floor that are not being used as abandoned and therefore need to be enclosed in a plenum rated box.

These cables are terminated and coiled up under the raised floor as spares for future so you do not have to run all the way back to the IDF closet if you need to add a Data cable at a cubicle.

I am saying these are spare and not Abandoned cables since they are labeled as Spares and terminated on both ends.

-Ed

 

[JFletcher]

I talked to the engineer who designed the Data Distribution and he indicated he has seen some inspectors consider cables installed under raised floor that are not being used as abandoned and therefore need to be enclosed in a plenum rated box.

In those cases, I would guess the red-tag comes from 830.2.

"Abandoned Network-Powered Broadband Communications Cable": Installed network-powered broadband communications cable that is not terminated at equipment other than a connector and not identified for future use with a tag.

The bolded portion would suggest to me that, if the cabling falls under 830, it has to be terminated at both ends with more than just a jack. I don't see how one could make that determination (800 or 830) on cat6 cables that are not connected to any equipment other than a jack.

As for the plenum rated box, I see no provision in the code for that as a requirement or acceptable alternative to removal. If the cable is abandoned, it has to be removed. If the cable is not CMP, and the underfloor space serves more than the IT room, I could see that spare cable be required to be enclosed in a box per 300.22(C)(2) as referenced by 800.3(B).

These cables are terminated and coiled up under the raised floor as spares for future so you do not have to run all the way back to the IDF closet if you need to add a Data cable at a cubicle.

I'm still failing to see exactly what the purpose is of leaving the terminated cables under the floor. Would you elaborate on the planned use of these cables? To what are they terminated? To where will they run? Are they long loops of cable with a keystone on each end? Please help me picture your install.

I am saying these are spare and not Abandoned cables since they are labeled as Spares and terminated on both ends.

-Ed

I agree with you there.


I couldn't find anything specific in article 645 that would prohibit you from leaving tagged and terminated cables underneath a raised floor.

Hal and Chris (and other inspectors), where are you?

 

[raider1]

If the cables have been tagged and identified for future use, then they are not abandonded and can remain.

Typically computer data cables will either be Article 800 installations or Article 725 Class 2 systems depending on what is being run in the cable. Both 800.25 and 725.25 permit cables that are tagged and identified for future use to remain.

Chris

 

[ed downey]

These are Cat 5E cables terminated with a RJ45 jack and left with a 20' coil of cable under the raised floor. They will be used in the event that another network printer is needed or another workstation will need to be set up in the office. This is not an Article 645 installation it is just an open office situation with raised access floor for HVAC, Power, & Data distribution that has furniture cubicles on top.

-Ed

 

[hbiss]

I agree with Chris. This is no different than the space above a ceiling. If they are tagged they can remain.

-Hal

 

[MisterCMK]

IIRC the space under the raise floor in a data center is not considered a plenum air space.

 

[ed downey]

This is not a Data Center. This is an open office with underfloor air distribution.

 

[cochise7969]

The new NEC 2002 requires that abandoned cable be removed for both copper and fiber.

The accumulation of miles and miles of cabling left in the ceilings and walls of facilities has become a major concern for life safety over the years. A recent Toxics Use Reduction Institute presentation at the RCRA National Conference - January 16, 2002 ) conservatively estimated that there is over 45 billion feet of plenum cable in place. Cables that are abandoned in ceilings, riser systems, and air handling systems have always been a source for fueling fire and smoke. The NEC 2002 requires the removal of abandoned cable to reduce the fuel load in case of a fire. The buildup of layers upon layers of cabling has become a major concern to life and safety over the past 10 years.

The definition of abandoned cable, as found in paragraphs 800.2 and 770.2 of the NEC 2002 Book, states "....Installed communications cable that is not terminated at both ends at a connector or other equipment and not identified "For Future Use" with a tag." Admittedly, this definition of abandoned cable in the NEC is somewhat vague.

Now what are we gonna do?

 

[erickench]

The NEC does'nt seem to have rules for Data Cables like Category 6 except maybe for intersystem bonding. The general rule for existing cables is the following: If they are exposed and not tagged for future use then they are considered abandoned and therefore must be removed. But I don't think this applies to Data Cables. It would apply however to telephone cables.

 

[tallgirl]

Unless everyone who has ever wired every data center I've ever set my foot in, since Jimmy Carter was President, has all done it wrong, leaving spares under the floor is acceptable.

 

[tom baker]

The NEC does'nt seem to have rules for Data Cables like Category 6 except maybe for intersystem bonding. The general rule for existing cables is the following: If they are exposed and not tagged for future use then they are considered abandoned and therefore must be removed. But I don't think this applies to Data Cables. It would apply however to telephone cables.

Yes the NEC does have rules for Cat 6. Its just the NEC does not use the term Cat 6. Look at the cable jacket and see what it states, then find the appropiate articles
Hint:
725
300
800

 

[tom baker]

IIRC the space under the raise floor in a data center is not considered a plenum air space.

It could be an air handling space. Keep in mind what we typically install plenum cable in is not the plenum. The plenum rarely has wiring installed in it and only when necessary.