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Cable Tray & Cable Ladder

     What is a Cable Tray System? Per the National Electrical Code, a cable tray system is “a unit or assembly of units or sections and associated fittings forming a rigid structural system used to securely fasten or support cables and raceways. Which means:

Cable trays support cable the way that roadway bridges support traffic

  • A bridge is a structure that provides safe passage for traffic across open spans.
  • Cable tray is the bridge that allows for safe transport of wires across open spans.
  • Therefore, think of cable tray as the structural component of a building’s electrical system.

Description & Selection

Since Cable Tray is used in a wide variety of applications and under widely varying conditions, it is important that you gain an understanding of material specifications and structural design, and apply that knowledge when selecting trays and specifying fittings, parts, and accessories.

Cable Tray systems provide rigid structural support for cables in a variety of commercial and industrial applications. The basic styles of cable tray are: Ladder, Perforated and Solid Bottom Channel Tray Type and WireMesh.


Ladder consists of two longitudinal side members ( side rail ) connected by individual traverse ( rung support ) members. It is intended for use as a power cable or control support.

Channel Tray

Channel is a one piece support with either ventilated perforated or solid bottom sections. These sections are used with a single power cable, multiple control, or signal circuit cables, which would provide better electrical shielding and better insulation mechanical protection from Foreign Object Damage ( FOD ).

Quick List Selection Proces

Some of the considerations for Cable Tray selection are

  1. Span Issues are : Strength and Length : verry important to first consider the support span as it affects the strength of the system and the length of the straight section required.
  2. Working Load Issue Are : Size ( Width, Loading Depth, and Strength ) Cable Load Types adn numbers of cable to support – total cable load in kg per linear meter ( kg/meter ), Power – is single layer – issue width (refer to local electrical code), Low Voltage – is stacked – issue loading depth and width (refer to affecting code) sellect a Cable Tray system that meets the working load for the support span required and a straight section length that fits the installation. Nema VE 2 – Straight sections equal to or larger than span.
  3. Installation Environment Isuue are : Material and Finish  :
  • Indoor Dry – Institutional, Office, Comercial, Light Industrial use Alumunium, Pre – Galvanized Steel, Electro Galvanized Steel
  • Indoor Industrial – Automotiive, Pulp and Paper, Power Plants use Alumunium, Pre-Galvanized Steel, Possibly Hot-Dipped Galvanized After Fabrication  (HDGAF)
  • Outdoor Industrial – Petrochemical, Automotive, Power Plant use Alumunium, Hot – Dipped Galvanized After Fabrication (HDGAF)
  • Outdoor Marine – Off Shore Platfoms use Alumunium, Stainlees Steel.

Nema Load Classification

     The National Electrical Manufactures Association ( NEMA ) has standardized the classification of Cable Tray based on the load to be cariied per foot, and the distance between span supports. Maximum Design Load for maximum Associated Support Spacing CSA Load Classification SCM manufactures Cable Tray in accordance with NEMA Standar Publication VE1-2005 and CSA Standard C22.2 No.126.1.

NEMA SUPPORT SPAN LOAD Standard Publication VE1-2005
CLASS (in feet) (lbs./foot) equal to meter (kg/meter)

8A  = 8 feet span   50 lbs/foot equal to 2.40 meters span  74kg/meter run
8B  = 8 feet span   75 lbs/foot equal to 2.40 meters span  112kg/meter run
8C  = 8 feet span   100 lbs/foot equal to 2.40 meters span  149kg/meter run
12A = 12 feet span   50 lbs/foot equal to 3.66 meters span  74kg/meter run
12B = 12 feet span   75 lbs/foot equal to 3.66 meters span  112kg/meter run
12C = 12 feet span   100 lbs/foot equal to 3.66 meters span  148kg/meter run
16A = 16 feet span   50 lbs/foot equal to 4.88 meters span  74kg/meter run
16B = 16 feet span   75 lbs/foot equal to 4.88 meters span  112kg/meter run
16C = 16 feet span   100 lbs/foot equal to 4.88 meters span  148kg/meter run
20A = 20 feet span   50 lbs/foot equal to 6 meters span  74kg/meter run
20B = 20 feet span   75 lbs/foot equal to 6 meters span  112kg/meter run
20C = 20 feet span   100 lbs/foot equal to 6 meters span  148kg/meter run

NEMA SUPPORT SPAN LOAD Standard Publication VE1-2005

A 25 lbs/foot, 10feet span= 37kg/meter, 3meter span
C 65 lbs/foot, 10feet span= 97kg/meter, 3meter span
D 45 lbs/foot, 20feet span= 67kg/meter, 6meter span
E 75 lbs/foot, 20feet span= 112kg/meter, 6meter span

Why Limit Deflection?

     The primary reason to limit deflection in cable tray systems is appearance. Engineers and owners take pride in the appearance of their installations. So grid restrictions on deflection of cable trays installed at eye level or in a prominent location are common. However, it is neither economical nor good engineering paractice to restrict deflection of a cable tray system in lees prominent areas.

Methods of Decreasing Deflection

There are various ways to limit deflection of a cable tray. If the objective is minimal installed cost, they should be considered this order : 

  • Deflection in any location can be reduced by increasing the depth of the load – carrying side members and/or by adding to their cross-sectional area. adding to the depth generally utilizes the material most economically.
  • Decreasing span length. For economic reasons, this method of reducing deflection should be a last resort, since it increases field labor considerably. However, it can be an effective means to improve the appearance of an installation when the number of spans to be reduced is smal in comparison to the number in the entire installation.

Materials and Construction

     Cable tray systems are commonly fabricated from a corrosion-resistant metal or from a metal with a corrosion-resistant finish. The selection of the proper material is essentially an economic consideration.

  • Aluminum Alloys Cable tray products are most widely formed from the 6000 series alloys. Alloys in this group contain silicon and magnesium in approximate proportions to form magnesium silicide, thus making them.
  • Steel Steel cable trays are used principally in environments which are relatively free from corrosive attack. They are available with various types of corrosion-resistant finishes; usually hot-dip galvanized. The main advantages of using steel in cable tray fabrication are its high strength and low cost. Its disadvantages are increased structural weight, poor corrosion-resistance, and low electrical conductivity.
  1. Hot rolled mild steel
  2. Following JIS 3131 / SPHC
  3. Or Equivanlent
  • Stainless Steel  Stainless steel contains at least 10 percent chromium, along with other elements to develop specific properties. Depending on the quality of the elements present in a stainless alloy, SCM B-TRAY product, offers cable trays and accessories in both the 304 and 316 series. These austenitic alloys are remarkable in several respects. Unlike the other two classes, they contain nickel in quantities from 4 to 22 percent, while the percentage of carbon is kept relatively low. When chromium is increased for improved corrosion resistance, nickel must also be increased to retain the austenitic structure 304 stainless steel has chromium and nickel increased and carbon lowered to reduce carbide precipitation and increase corrosion resistance. Lowering the carbon content also makes welding easier. 316 stainless steel has molybdenum added to improve corrosion resistance and high temperature strength. The carbon content is also lowered to improve welding performance.

Metalic Finishes Galvanized

     Cable trays fabricated of steel can be protected from corrosion by coating with another metal, the most effective way and commonly use for protecting the Metalic Cable Tray is Zinc Coated also know as Galvanizing, Zinc protects steel in two ways. First it protects the steel as a coating and second as a sacrifical anode to repair bare areas such as cut edges, scratches, and gouges. The corrosion protection of zinc is directly related to its thickness and the environment. This mens a 0.2 mill coating will last twice as long as a 0.1 mil coating in the same environment. The Zinc coating or galvanizing process using one of the following methods: 

     Electro Galvanized Zinc Recomended Use Indoor. Electro galvanized Zinc ( also know as zinc plated or electroplated ) is the process by which a coating of zinc is deposited on the steel by electrolysis from a bath of zinc salts. This finish is standard for cable tray hardware and some accessories. Zinc Plated standard, provides a tough, adherent, protective film consisting of a mixture of zinc oxides, hydroxides, and carbonates. This fim is in itself a barrier coating which slow subsequent corrosive attack on the zinc. This coating is usually recommended for indoor use in relatively dry areas, as it provides ninety-six hours protection in salt spray testing per ASTM B117.

  Our finishing proces from fabrication of cable tray and ladder system is Hot Dip Galvanized, with method with min thickness 65 micron. ( Other finishing proscess such as powder painted, electri galvanized, etc by requested ). Hot  Dip Galvanized processing shal comply with standart   AS/NS 4680.

    All our fabrication finishing of cable tray and cable ladder system is HDG and provide and original HDG certificate for the product from HDG company where the galvanizing of cable ladder are produced.



Hot Dip Galvanized is dipping process to coat steel with melting zinc as rust protecting, with step below :

  1. Degreasing ( to clear oli, grease in surface steel )
  2. Rinsing Degresing ( to clear degreasing residual )
  3. Pickling ( to clear rusted mill scale )
  4. Rinsing Pickling ( to clear pickling residual )
  5. fluxial ( to conditioning of steel surface )
  6. Zinc Bath ( to coat steel surface with melting zinc in 450-460 c )
  7. Quenching ( to passivation of zinc coating to avoid premature oxidize ).