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The recently released National Electrical Code (NEC, 2005) amends the way cable should be extended out of cable trays. Once limited to the use of metal clad (MC) cables or metal conduit, the 2005 Code - specifically Section 725.61 (D) (4) for Power Limited Tray Cable (PLTC), and Section 336.10(7) for Tray Cable (TC) - permits the use of UL Exposed Run (-ER) Compliant cable.
600 Volt Type TC Cables that meet or surpass required crush and impact test criteria as per the 2005 NEC Code, Section 336.10 (7) are marked "TC-ER".
Type PLTC Cables that are certified to meet crush and impact resistance test requirements are marked "Open Wiring" or "Open Wire" as per 2005 NEC Code, Section 725.61 (D) (4).
For both TC Tray Cables and PLTC Cables, the 2005 NEC Code now allows unlimited length runs to extend from the tray, assuming the Code requirements for local mechanical protection are observed. (The length of the permitted run depends upon the specific Code adopted by the locality. If the locality continued to conform to the 2002 NEC Code, then there is a 50-ft. length restriction for PLTC cable.)
Alpha Wire Company now provides a solution to this unique application through the Alpha Wire INDUSTRIAL SERIES: SERIES
F, SERIES M, SERIES
L, SERIES
P and SERIES V.
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THE
2005 NATIONAL ELECTRICAL
CODE REQUIRES UL
EXPOSED RUN (-ER) CABLES
EXTENDING FROM CABLE TRAYS
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2005
NATIONAL ELECTRICAL CODE –
SECTION 725.61 (D) (4)
Type PLTC Cables
(D)
Hazardous (Classified) Locations. Cables installed
in hazardous locations shall be as described in
725.61(D)(1) through (D)(4).
(4)
In Industrial Establishments. In Industrial Establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation, and where the cable is not subject to physical damage, Type PLTC cable that complies with the crush and impact requirements of Type MC cable and is identified for such use shall be permitted to be exposed between the cable tray and utilization equipment or device. The cable shall be continuously supported and protected against physical damage using mechanical protection such as dedicated struts, angles, or channels. The cable shall be secured at intervals not exceeding 1.8 m (6 ft).
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2005
NATIONAL ELECTRICAL CODE –
SECTION 336.10(7)
Type TC Cables
336.10
Uses Permitted – Type TC tray cable shall
be permitted to be used in the following:
(7)
In industrial establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation, and where the cable is continuously supported and protected against physical damage using mechanical protection, such as struts, angles, or channels, Type TC tray cable that complies with the crush and impact requirements of Type MC cable and is identified for such use with the marking Type TC-ER shall be permitted between a cable tray and the utilization equipment or device. The cable shall be secured at intervals not exceeding 1.8 m (6 ft.). Equipment grounding for the utilization equipment shall be provided by an equipment grounding conductor within the cable. In cables containing conductors sized 6 AWG or smaller, the equipment grounding conductor shall be provided within the cable or, at the time of installation, one or more insulated conductors shall be permanently identified as an equipment grounding conductor in accordance with 250.119(B).
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Reprinted
with permission from NFPA 70-2002, The National Electrical Code,
Copyright © 2001, National Fire Protection Association, Quincy,
MA 02269. This reprinted material is not the complete and official
position of the NFPA on the referenced subject, which is represented
only by the standard in its entirety. National Electrical Code and
NEC are registered trademarks of the National Fire Protection Association,
Quincy, MA.
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