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.