Fiberglass Cable Tray & Channel Standards The standards commonly referenced in specifying cable tray are the National Electric Code ® , Article 392-Cable trays; NEMA
included in the NEMA Standard; however, it has been designed and tested to comply with the intent of NEMA FG 1. A safety factor 1.5 times the type LC working load of 50 lbs./linear foot for a 12 foot length has been confirmed by NEMA FG 1 test methods. Type LC cable tray meets the requirements of Class C1 in the CAN/CSA-C22.2 No. 126-M91 standard. Considerations for Cable Tray Deflection Cable Tray load testing as specified by NEMA Standard FG 1 requires the test article to be a single length of tray simply supported at each end (referred to as a simple beam configuration - see diagram next page). This requirement was established to standardize testing and because it is impractical to test large tray system assemblies to destruction. Most actual tray installations consist of multiple lengths of connected tray with multiple supports (referred to as a continuous beam configuration). The most significant difference between a continuous versus simple beam configuration is that for continuous beam, the presence of adjacent lengths of tray affect the deflection of the tray in the section of interest. With the same loading and support span, the maximum deflection is dramatically less for continuous compared to simple beam. For example, in the NEMA FG 1 simple beam test, Class CE fiberglass cable tray deflects approximately 3.75" at the mid-point of a 20' support span while carrying its rated load of 100 pounds per foot. In continuous beam, the maximum mid-span deflection would be only 0.8" or 20% of that for simple beam.
Standards Publication NO. FG 1, Fiberglass Cable Tray Systems; Canadian Standards Association CAN/CSA-C22.2 No. 126-M91, Cable Tray Systems and Underwriters Laboratories Inc. Standard UL-568, CYOV Non-Metallic Cable Trays. ASTM and UL standards are also referenced to characterize the materials used to construct the fiberglass cable tray. ASTM standards define physical properties tests for the materials used to pultrude the cable tray. The specific ASTM test methods for mechanical, thermal and flammable properties are identified in the Construction and Physical Properties Section. UL flammability standards applied to fiberglass cable tray materials are also identified in the same section. ASTM and UL standard material properties for fiberglass channel and strut are identical to those of the cable tray because they are pultruded from the same materials. Load Standards Section 3 of NEMA FG 1 provides the performance standards and class designations for fiberglass cable tray systems. Based on a twenty foot support span, three working load classifications are recognized: Fiberglass "Z" Style is available in one load classification. The deep tray, which provides six inches of cable fill depth, is designated as type CZD for its respective NEMA class. The "E" Style tray is available in two load classes, which are designated as type BE and type CE for the respective NEMA classes. All fiberglass tray styles have a 1.5 safety factor and exceed the NEMA FG 1 requirement for the allowable working load. The Low Profile Cable Tray, type LC, is not yet
Load Standards
Load Class
Allowable Working Load
A
50 lbs./linear ft.
B
75 lbs./linear ft.
GLAS - Advantages
C
100 lbs./linear ft.
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