Conduit

[William P Donnelly]

Does 4 pair voice/data wire need to be rated underground (gel filled) if it is in conduit in a slab on the inside of a building? I have a Dade County electrical inspector who says that it is.
Thanks
Donnelly

 

[ed downey]

I would say he is correct due to the definition of a Wet Location in Article 100.
Location, Wet. Installations under ground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

Also the following is referencing the 2002 NEC & BICSI Standards.

Research into the various codes and design methods for under-slab conduit construction reveals that 300.5(D)(5) of the 2002 NEC requires that ?cables and insulated conductors installed in enclosures or raceways in underground installations shall be listed for use in wet locations.? In addition, BICSI?s Telecommunications Distribution Methods Manual, Chapter 4, Section 1, page 4-5, under the heading ?Wet Locations? states, ??slab-on-grade construction where pathways are installed underground or in concrete slabs that are in direct contact with soil (e.g., sand, gravel, etc.) are considered to be ?wet locations?.?

Hope this helps.

-Ed

 

[rexowner]

I agree it should be rated underground. There is
direct burial cable that is not gel-filled if you don't
want to deal with the gel.

I have used this stuff with no problems in underground
raceways:
http://www.sellntell.com/find_htm/pb.htm?action=item&SK=439

 

[iwire]

If the cables in question fall under an Article in Chapter 8 then 300.5(D)(5) does not apply.

 

[infinity]

If the cables in question fall under an Article in Chapter 8 then 300.5(D)(5) does not apply.

That was my thought too. The NEC doesn't really care about what happens to those cables.

 

[rexowner]

The NEC requirement was a little unclear in my mind, so I
went back and re-read Article 800. Iwire's statement
is correct. Moreover, while there are actual communications
cables manufactured for wet locations, if you look at the
types of CM cable listed in Table 800.179, there is not even
a type for "wet" or "underground." If there was a NEC
requirement for "wet" communications cables, one
would expect them to be part of the discussion of 800.179,
which they are not.

I have always installed wet-rated low-voltage cables,
e.g. in raceways between buildings, because I am
somewhat conservative, and I generally don't want to
go back and revisit the installations for degraded
cable. But, it's not a NEC requirement.

 

[nc5p]

Mind you this was some years back (in a former life) but I installed thousands of feet of telephone cable in pvc conduit under the slab in many commercial buildings. None of it was flooded. The only time we did was if it was going outside, like to another building.

 

[hbiss]

There is nothing to say that you can't do it that way. Common sense and experience will tell you to use flooded.

-Hal

 

[tom baker]

If the cables in question fall under an Article in Chapter 8 then 300.5(D)(5) does not apply.

This information is in section 90.3
The cable does not need to be in conduit, and there is no burial depth requirement.
However if you want it to work then a cable for a wet location is required or a "flooded" cable. Much of the flooded cable is not UL listed, make sure of the AHJ requirements.

 

[telhack]

Telephone cable in conduit direct burial

Telephone cable in conduit direct burial

I got bit on this last week. It is easier to just do what the inspectors want even though they are wrong. Today, the same inspector on the follow-up inspection counts the wires in the outlets and proclaims that I have less wires than what is on the plans and that the plans have to be revise for final. For Telephone cables!!!! The drawing showed 17 wires and I had 12, in another outlet the drawing had 8 and I had 7!! He didn't care that I had more cables than shown but not less.

Anyway, I agree that telephone cable is not covered by the section of code they refer to on direct burial requirements. It is a good practice especially in conduits going outside. I've seen my share of deteoriated cable; but inside a building in a controlled environment? In my particular case I had a conduit coming down the wall from the drop ceiling. The strip mall storefront did not want power poles coming down so they cut a section of the floor to run electrical and comm from the wall out 10 feet.

The code section they refer to is Article 310 they say "All conductors installed in raceways underground, in concrete slabs or masonry in direct contact with the earth must be suitable for wet locations. I can't find this specfic wording anywhere in my book. Section 310.8 talks about locations, (C) says of a type listed for use in wet locations, and section 310.13 is a table of cable types which direct burial telephone cable is not listed anywhere on the table.
But Article 310.1 Scope it states " this article covers general requirements for conductors ....... and uses. These requirements do not apply to .... to conductors specifically provided from elsewhere in this Code. Article 300 Wiring Methods 300.1 also says this article doesn't cover installations modified by other articles.
In Article 800 Section V 800.48 the only entries regarding raceways said that the raceway shall be of a type permitted & installed in accord. with Chapter 3. Then in 800.51 (E) is says that CMX cable shall be listed as being suitable for use in raceway. So I see nothing that says that we have to use direct burial telephone cables in a conduit under slab in interior spaces.