Conduit in slab deemed a "wet location"?

[Dedicon]

We are planning to install data cabling in a retail store which will have some runs from the cash wrap in the middle of the store going through about 10'-20' of conduit in the slab before reaching a support beam where it will rise up to the ceiling joists to head back to the rack. According to the GC, the electrical contractor on site is stating the cable must be rated for a "wet location". I have not encountered this situation before and the only way I know to address this is to use burial cable, which seems like a ridiculous option which will cost the owner much additional expense, not to mention that the installed conduits may then not be large enough to accomodate. Can anyone offer any insight on this...doesn't seem right that this scenario should be deemed a "wet location" in the first place.

 

[iwire]

The NEC definitely considers conduit in a slab to be a wet location.

The NEC definitely requires the EC to use conductors and cables for power and lighting circuits to be rated for wet locations.

However, there is nothing in the NEC that I am aware of that requires data and voice conductors and cables to be wet location rated.

 

[izak]

underground conduit in my experience almost Always contains some amount of water

 

[nhfire77]

As Iwire stated in concrete is a "wet location" Ive done FA pull stations that are on a glass wall exit door. The EC stubs it up right next to the door and we add on to it to the J-box.

We installed IMSA cable to each one of the pulls, 14 in all I believe. It was definitely over the pipe fill, but it was safe just being a trip loop to an input device.

It stinks, I know, but that's code.

 

[goldstar]

You will definitely get some water or moisture inside a conduit buried in concrete. As was previously mentioned by Bob (Iwire) I don't believe data cable in buried conduit has the same NEC requirements as line voltage wiring.

Just a suggestion, anytime I bury PVC I use the primer (like the plumbers purple stuff only clear) before joining conduits together. You'll still get some moisture due to condensation inside the PVC but at least you have a better chance of not getting any underground water seepage inside due to a poor fitting. Just my two cents worth.

 

[Smart $]

However, there is nothing in the NEC that I am aware of that requires data and voice conductors and cables to be wet location rated.

I not aware of anything which alleviates the requirement to be wet location rated...

300.1 Scope.

(A) All Wiring Installations. This article covers wiring methods for all wiring installations unless modified by other articles.

...

300.5 Underground Installations.
...

(B) Wet Locations. The interior of enclosures or raceways installed underground shall be considered to be a wet location. Insulated conductors and cables installed in these enclosures or raceways in underground installations shall be listed for use in wet locations and shall comply with 310.8(C). Any connections or splices in an underground installation shall be approved for wet locations.

...

310.8 Locations

?

(C) Wet Locations. Insulated conductors and cables used in wet locations shall comply with one of the following:
(1) Be moisture-impervious metal-sheathed
(2) Be types MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, ZW
(3) Be of a type listed for use in wet locations

...

 

[infinity]

I not aware of anything which alleviates the requirement to be wet location rated...

Your reference was to a chapter 3 wiring method. Bob was likely thinking of this:

90.3 Code Arrangement.
This Code is divided into the introduction and nine chapters, as shown in Figure 90.3. Chapters 1, 2, 3, and 4 apply generally; Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions. These latter chapters supplement or modify the general rules. Chapters 1 through 4 apply except as amended by Chapters 5, 6, and 7 for the particular conditions.
Chapter 8 covers communications systems and is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8.

 

[Smart $]

Your reference was to a chapter 3 wiring method. Bob was likely thinking of this:

Perhaps... but I was going by this...

V. Installation Methods Within Buildings
800.110 Raceways for Communications Wires and cables. Where communications wires and cables are installed in a raceway, the raceway shall be either of a type permitted in Chapter 3 and installed in accordance with Chapter 3 or listed plenum communications raceway, listed riser communications raceway, or listed general-purpose communications raceway installed in accordance with 800.154 and installed in accordance with 362.24 through 362.56, where the requirements applicable to electrical nonmetallic tubing apply. The raceway fill tables of Chapter 3 and Chapter 9 shall not apply.

For the time being, I'm assuming the EC did not use listed communications raceway.

 

[infinity]

Perhaps... but I was going by this...
For the time being, I'm assuming the EC did not use listed communications raceway.

It might be splitting hairs but IMO this only applies to the raceway installation and not the cable within it:

V. Installation Methods Within Buildings
800.110 Raceways for Communications Wires and cables. Where communications wires and cables are installed in a raceway, the raceway shall be either of a type permitted in Chapter 3 and installed in accordance with Chapter 3 or listed plenum communications raceway, listed riser communications raceway, or listed general-purpose communications raceway installed in accordance with 800.154 and installed in accordance with 362.24 through 362.56, where the requirements applicable to electrical nonmetallic tubing apply. The raceway fill tables of Chapter 3 and Chapter 9 shall not apply.

 

[Smart $]

It might be splitting hairs but IMO this only applies to the raceway installation and not the cable within it:

It's the part that says "installed in accordance with Chapter 3"... and the earlier referenced parts of Chapter 3 installation requirements say, "Insulated conductors and cables installed in these enclosures or raceways in underground installations shall be listed for use in wet locations and shall comply with 310.8(C)." So you now have to go back to Chapter 8 and find something that says the cabling does not have to be wet location rated.

 

[infinity]

It's the part that says "installed in accordance with Chapter 3"... and the earlier referenced parts of Chapter 3 installation requirements say, "Insulated conductors and cables installed in these enclosures or raceways in underground installations shall be listed for use in wet locations and shall comply with 310.8(C)." So you now have to go back to Chapter 8 and find something that says the cabling does not have to be wet location rated.

I'm follow your reasoning but I'm not seeing where these cables are underground.

 

[Smart $]

I'm follow your reasoning but I'm not seeing where these cables are underground.

OK, you have a point on which the OP did not elaborate... but I'm assuming the slab mentioned in the OP is on the ground floor and supported by the ground underneath the slab. A raceway or section thereof not entirely above the top surface of such slab is considered under the building and its installation methods are covered under 300.5 Underground Installations, and it is from a subsection thereof that I quoted.

 

[iwire]

I not aware of anything which alleviates the requirement to be wet location rated...

Assuming the voice / data lines are covered by an Article in Chapter 8, section 90.3 alleviates the requirement for these voice / data lines to be wet location rated.

 

[infinity]

Assuming the voice / data lines are covered by an Article in Chapter 8, section 90.3 alleviates the requirement for these voice / data lines to be wet location rated.

I can see Smart's point. 800.111 sends you to article 300 which says that raceways in wet locations require cables in wet locations to be wet rated.