Cable Tray

stanleycochran · Aug 20, 2005

What are the guidelines for installing cable tray cable, 3 phase, 4 wire, 277/480 volt in metallic conduit ????

iwire · Aug 20, 2005

Re: Cable Tray

Article 336

redfish · Aug 20, 2005

Re: Cable Tray

ARTICLE 336 Power and Control Tray Cable: Type TC

I. General
336.1 Scope
This article covers the use, installation, and construction specifications for power and control tray cable, Type TC.
336.2 Definition
Power and Control Tray Cable, Type TC. A factory assembly of two or more insulated conductors, with or without associated bare or covered grounding conductors, under a nonmetallic jacket.
II. Installation
336.10 Uses Permitted
Type TC cable shall be permitted to be used as follows:
(1) For power, lighting, control, and signal circuits.
(2) In cable trays.
(3) In raceways.
(4) In outdoor locations supported by a messenger wire.
(5) For Class 1 circuits as permitted in Parts II and III of Article 725.
(6) For non?power-limited fire alarm circuits if conductors comply with the requirements of 760.27.
(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).
(8) Where installed in wet locations, Type TC cable shall also be resistant to moisture and corrosive agents.
336.12 Uses Not Permitted
(1) Installed where it will be exposed to physical damage
(2) Installed outside a raceway or cable tray system, except as permitted in 336.10(7)
(3) Used where exposed to direct rays of the sun, unless identified as sunlight resistant
(4) Direct buried, unless identified for such use
336.24 Bending Radius
Bends in Type TC cable shall be made so as not to damage the cable. For Type TC cable without metal shielding, the minimum bending radius shall be as follows:
(1) Four times the overall diameter for cables 25 mm (1 in.) or less in diameter
(2) Five times the overall diameter for cables larger than 25 mm (1 in.) but not more than 50 mm (2 in.) in diameter
(3) Six times the overall diameter for cables larger than 50 mm (2 in.) in diameter
Type TC cables with metallic shielding shall have a minimum bending radius of not less than 12 times the cable overall diameter.
336.80 Ampacity
The ampacity of Type TC tray cable shall be determined in accordance with 392.11 for 14 AWG and larger conductors, in accordance with 402.5 for 18 AWG through 16 AWG conductors where installed in cable tray, and in accordance with 310.15 where installed in a raceway or as messenger supported wiring.
III. Construction Specifications
336.100 Construction
A metallic sheath or armor as defined in 330.116 shall not be permitted either under or over the nonmetallic jacket. Metallic shield(s) shall be permitted over groups of conductors, under the outer jacket, or both.
336.104 Conductors
The insulated conductors of Type TC tray cable shall be in sizes 18 AWG through 1000 kcmil copper and sizes 12 AWG through 1000 kcmil aluminum or copper-clad aluminum. Insulated conductors of sizes 14 AWG and larger copper and sizes 12 AWG and larger aluminum or copper-clad aluminum shall be one of the types listed in Table 310.13 or Table 310.62 that is suitable for branch circuit and feeder circuits or one that is identified for such use.
(A) Fire Alarm Systems Where used for fire alarm systems, conductors shall also be in accordance with 760.27.
(B) Thermocouple Circuits Conductors in Type TC cable used for thermocouple circuits in accordance with Part III of Article 725 shall also be permitted to be any of the materials used for thermocouple extension wire.
(C) Class 1 Circuit Conductors Insulated conductors of 18 AWG and 16 AWG copper shall also be in accordance with 725.27.
336.116 Jacket
The outer jacket shall be a flame-retardant, nonmetallic material.
336.120 Marking
There shall be no voltage marking on a Type TC cable employing thermocouple extension wire.

This is from the 2005 CODE, hope it helps.

Cable Tray

stanleycochran

Member

iwire

Moderator

redfish

Senior Member