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SECTION 26 0519.13 – UNDERCARPET ELECTRICAL POWER CABLES

SUPPLEMENTAL INFORMATION

By Joe Moreland, PE, CSI (GA PE#26321)

GENERAL DESCRIPTION

Undercarpet cable systems consist of floor-mounted power and communication service fittings served by flat cables designed to be installed on hard, smooth floor surfaces (typically concrete) and concealed beneath carpet tiles. This system can be used for both existing building renovations and new construction. For renovations, it provides an alternative to cutting and patching of existing floors or adding power poles. For new construction, it provides flexibility in accommodating future changes to furniture and equipment layouts. System modifications can be easily made to the accessible components through removal and subsequent reinstallation of carpet tiles.

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SYSTEM COMPONENTS    

Undercarpet power cable is listed Type FCC flat conductor cable, as defined in NFPA 70. It consists of three to five copper conductors separated by laminated plastic strips enclosed within an insulating jacket assembly. Three-conductor cables are limited to distribution of power for a single circuit. Five-conductor cables are capable of distributing power for up to three circuits (two circuits when one of the conductors is an additional isolated ground).

Undercarpet communications cable is listed Type CMUC undercarpet cable, as defined in NFPA 70. It is 4-pair, UTP (unshielded twisted pair) cable with TIA-568 Category selected to meet or exceed premises communication horizontal cable.

Category 5e:  Rated to maximum frequency of 100 MHz. Suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T (Gigabit Ethernet).

Category 6:  Rated to a maximum frequency of 250 MHz. Suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T (Gigabit Ethernet), 10GBASE-T (10-Gigabit Ethernet). Compared to Category 5e, Category 6 features more stringent specifications for crosstalk and system noise.

Service fittings are used to distribute power and/or communications service along the undercarpet cable path. Fittings may contain receptacles, voice and data jacks, or a combination of both.

Receptacles are of the direct connecting type, utilizing insulation-piercing lances that make contact with the conductors when the receptacle is secured. Receptacles may be 15 A or 20 A, and may be standard ground or isolated ground type.

Communications fittings utilize ports that accept modular voice and data jacks with TIA-568 Category that matches the cable being terminated.

Flexible power whips may also be used to distribute power to modular furniture or equipment using a service fitting that provides a flexible metal conduit/cable connection. A transition block located inside the service fitting provides an interface between the flat undercarpet cables and the conventional round conductors in the whip.

Transition fittings are boxes that house transition blocks used as an interface between round premises power and communications wiring and flat undercarpet cables. Power transition blocks utilize insulation-piercing connectors and communications transition blocks utilize standard insulation displacement connectors. Transition fittings may be located in walls, columns, or floors and may be flush mounted or surface mounted.

Accessories:

Floor preparation material is installed under cables to protect against floor moisture, chemical reaction, and abrasion.

Tap and splice connectors are used to join two undercarpet power cables together. They utilize insulation-piercing lances that make contact with the conductors inside the cable when a manufacturer supplied crimping tool is applied.

Insulator assemblies are adhesive-faced material used to insulate and protect exposed conductors such as at taps and splices, ends of cables, and locations where existing service fittings have been removed.

Top shields are corrosion-resistant steel covers installed over cables to provide physical protection. They are also grounded and bonded together to reduce electrical hazards.

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INSTALLATION PROCEDURE

Prepare floors by scraping, patching, cleaning, and vacuuming. Floors should be smooth and free of irregularities.

Install transition fittings where premises wiring systems will interface with undercarpet cable system.

Install floor preparation material on floor surface along cable path where applicable.

Undercarpet Power Cable Installation:

Undercarpet Communications Cable Installation:

Install service fittings, ensuring proper conductor connections.

Test undercarpet power cable conductors for continuity prior to installation of top shield.

Install top shield over undercarpet cables. Installation of a top shield is generally required for undercarpet power cables. Installation of a top shield for undercarpet communications cables is usually considered optional, and may be desirable for extra protection in high traffic areas. Use manufacturer's supplied bonding clips at taps, splices, and changes in direction to achieve ground continuity of shield for entire power circuit path.

Energize and test each device to verify operation and proper polarity prior to installation of carpet tile.

APPLICABLE CODES AND STANDARDS

NEMA UC 2 – Undercarpet Power Distribution Systems, available for free download at www.nema.org, includes requirements for undercarpet power cable and associated fittings.

NFPA 70 (NEC) Article 324 contains requirements for flat conductor cable (Type FCC), including uses permitted and uses not permitted.

NEC 324.12 mandates that Type FCC cable is NOT permitted:

NEC 324.18 includes requirements for crossings of cables.

NEC 324.40 requires a top shield to be installed over Type FCC cable, and bonded together and with other system components using connectors.

NEC 324.41 contains requirements for floor coverings installed over Type FCC cable.

NFPA 70 (NEC) Article 800 contains requirements for Type CMUC undercarpet communications cables, including applications for which cable is permitted and not permitted.

OTHER CONSIDERATIONS

At one time there were at least three major manufacturers of undercarpet cables – AMP Incorporated, Thomas & Betts Corporation, and Hubbell Incorporated. Of these, only the first continues to manufacture these products, now doing business as TE Connectivity. The specifier should consider typical concerns associated with sole source projects.

Building Industry Consulting Service International (BICSI), suggests in its Telecommunications Distribution Methods Manual (TDMM) and Information Transport Systems Installation Methods Manual (ITSIMM) that undercarpet communications cable should be considered onlywhere other pathway systems are not available or applicable. Visit www.bicsi.org for more information.

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HOW TO SPECIFY

Start in UNDERCARPET CABLES under PART 2, progress to PART 3, and finish up with PART 1.

PART 2:

MANUFACTURERS Article:  Specify acceptable manufacturers. Only one manufacturer is offered in the specification text. See “Other Considerations” above for more information.

UNDERCARPET CABLE SYSTEM Article:  Indicate if scope is a new system or additions and modifications to an existing system.

“Undercarpet Power Cable” Paragraph:  Include if system includes power distribution (this is usually the case, but not always). Include paragraph for isolated grounding conductor if applicable. Cables with isolated grounding conductors should be clearly indicated on drawings.

“Undercarpet Communications Cable” Paragraph:  Include if system includes communications distribution (this is usually the case, but not always). The default option in the choice requires the contractor to match the TIA-568 Category to the premises communications horizontal cable. Alternatively use the choice to select the required category.

“Service Fittings” Paragraph:

“Transition Fittings” paragraph is automatically turned on via linking if the scope is designated as a new system. If the scope is designated as modifications and additions to an existing system, include this paragraph where new interface with premises wiring systems is required.

“Accessories” Paragraph:

PART 3:

EXAMINATION and PREPARATION articles are optional.

INSTALLATION is turned on automatically via linking. Applicable installation requirements for system components are turned on automatically via linking according to selections made under Part 2.

FIELD QUALITY CONTROL, CLEANING, and PROTECTION articles are optional.

PART 1:

SECTION INCLUDES:  Corresponding system components will be activated via linking according to selections made under PART 2.

RELATED REQUIREMENTS: Will automatically include other sections cited within the specification text (except for standard Division 1 cross references). Other sections may be listed because they include items that might be expected to be found within this Section or include items important for the completion of the work that are not specified in an obvious location (e.g. isn’t obvious from the section title).

REFERENCE STANDARDS: Will automatically include standards cited within the specification text. If the Consolidated List of Citations option is active, cross sectional links (not visible in the links window) will activate the reference standard in Section 01 4219 – Reference Standards as well.

ADMINISTRATIVE REQUIREMENTS: Includes optional text for a pre-installation meeting.

SUBMITTALS: Edit according to project requirements.

QUALITY ASSURANCE: Qualifications for manufacturer and product listing organization may be included.

DELIVERY, STORAGE, and HANDLING article is optional.

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