MATERIALS
| MATERIAL | MATERIAL SPECIFICATION | ADVANTAGES |
|---|---|---|
| Steel | ASTM JIAS BS EN ISO | |
| Stainless Steel | AISI Type 304 or All Type 316 |
Steel
Steel cable ladder (siderails and rungs) and cable channel are continuous roll-formed from structural quality steel. By cold working steel, the mechanical properties are increased allowing the use of a lighter gauge steel to carry the required load. This reduced the dead weight that must be carried by the supports and the installers.
Stainless Steel
Stainless Steel cable ladders are non-magnetic and belong to the group called austentic stainless steel. Like carbon steel, they exhibit increased strength when cold worked by roll-forming or bending.
Conditions that require the use of stainless steel imperative include long term maintenance costs, corrosion resistance, appearance and locations where product contamination is undesirable. Stainless steel exhibits stable structural properties such as yield strength and high creep strength at elevated temperatures.
A detailed study of the corrosive environment is recommended when considering a stainless steel design.
TECHNICAL DATA
| FINISH | SPECIFICATION | RECOMMENDED USE |
|---|---|---|
| Electrogalvanized Steel | BS1449 part 3 (Hardware & Accessories) | Indoor |
| Pre-galvanized Zinc | ASTM A52 G90 (Tray & Fittings) | Indoor |
| Hot Dip Galvanised Zinc | ASTM A123, BS:EN:ISO 1461 (1999), BS 729 | Indoor / Outdoor |
| Stainless Steel 316, 304 | ASTM 240 (Aluminium or Steel Tray & Fittings) | Chemical Environments (Outdoor) |
| Special Paint | Per Customer Specification (Aluminium or steel Tray & Fittings) | Indoor |
| Epoxy Coated | SS249 or as per manufacturer standard | Indoor |
Zinc Coatings
Zinc protects steel in two ways. It protects the steel as a coating and as a sacrificial anode to repair bare areas such as cut edges, scratches and gauges. The corrosion protection of zinc is directly related to its thickness and the environment. The means a 0.2 mil coating will last twice as long as a 0.1 mil coating in the same environment.
Electrogalvanized Steel
Electrogalvanized Steel (also known as steel plated or electroplated) is the process by which a coatings or steel is deposited by electrolysis from a bath of steel.
The coating is pure and is metallically bonded. A maximum of 0.5 mil of steel can be applied by this method.
The film is in itself a barrier coating which slow subsequent corrosive attacks. This coating is usually recommended for indoor use in relatively dry areas.
Pre-galvanized Zinc
Pre-galvanized steel is produced by coating coils of steel with zinc at the mills. This is known as mill galvanized or hot dip mill galvanized. These coils are then slit to size and fabricated by roll forming, shearing, punching or forming to produce pre-galvanized cable tray products.
During fabrication cut edges and welded areas not normally zinc coated. However, the zinc near the uncoated metal becomes a sacrificial anode to protect the bare areas after a short period of tie.
Pre-galvanized steel is not used outdoors but is suitable for extended exposure in dry or mildly corrosive atmospheres.
Hot Dip Galvanized After Fabrication
Hot Dip Galvanized cable ladder products are fabricated fro steel and the completely immersed in a bath of molten zinc. A metallic bond occurs resulting in a zinc coating that completely coats all surfaces, including edged and welds.
The most important advantage of this method is coating thickness. Cable tray hot dip galvanised after fabrication have a minimum thickness of 460 / sqm.
The layer of zinc which bond to steel provides a dual protection against corrosion. It protects first as an overall barrier coating. If this coating happens to be scratched of gouged, zincs secondary defence is called upon to protect the steel by galvanic action.
Hot dip galvanised after fabrication is recommended for prolonged outdoor exposure and will protect steel for many years in most outdoor environments and many industrial environment.
Cable Ladder Rails
The wall thickness of materials used shall not be less than 1.5m thick and the appropriate materials shall be recommended by the manufacturer so as to achieve the loading already selected.
The rail section shall be spaced able to accept a clip-on connector plated on either end, mechanically bolted to achieve structural strength at the joints. Connector plates can be removed from the rail section without having to dismantle any part of system.
STRUCTURAL CHARACTERISTICS OF CABLE LADDER AND SUPPORTS
When installed a cable ladder system performs functionally as a beam configurations. All four types of beams support cable ladder but each differ in the way that the beam is attached to the support.
The first two beam configurations, simple and continuous, apply to the cable ladder itself. The second two beam configurations, cantilever and fixed, apply more to the cable ladder supports than to the cable ladder itself.
Simple Beam
A good example of simple beam is a single straight section of cable ladder supported but not fastened at either end. When loaded the cable ladder is allowed to bend or flex.
Simply beam analysis is used almost universally for beam comparisons even thought it is seldom practical in field installations. The three most prominent reasons for using a simple beam analysis are: calculations are simplified: it represents the worst case loading: and testing is simple and reliable.
Continuous Beam
This is the beam configuration most commonly used in cable ladder installations. An example of this configuration is where cable ladder are installed across several supports to form a number of spans. The continuous beam posses traits of both the simple and fixed beams.
When equal loads are applied to all spans simultaneously, the counter-balancing effect of the loads on both sides of a support restricts the movement of the cable ladder at the support. The substantially like simple beams. When cable ladders of identical design are compared, continuous beam installations will typically have approximately half the deflection of a simple beam data should be used for general comparison only.
Cantilever Beam
This configuration occurs when one end of the beam is rigidly attached to the support and the other end is unsupported.
Is is typically used when wall mounting a bracket to support cable ladder. Sine one end is unsupported, the cantilever beam will hold considerably less load than a comparable simple beam.
Fixed Beam
This configuration has both ends of the beam rigidly attached to the supports. A good example of a fixed beam is the rung of a cable ladder. By welding the ends of the rung to the siderails, then end are not free to move, bend or twist, thus effectively increasing the load carrying capacity of the member.
They are also typically found in strut rack type support system found extensively in tunnel applications for support of pipe and cable tray.
Connectors
The strength of the siderails is important. These load bearing siderails must be connected to form a continuous system. Therefore the design of the connected plate needs to be both strong and simple to install. These characteristics are found in our connector plates.
The location of connectors in continuous span cable ladder system is also very important. the connectors should be located at points of minimum stress whenever practical.
SELECTION OF MATERIAL AND FINISH
The most suitable material and finish for your application will depend on cost, the potential for corrosion, and electrical consideration. Fore-Sight offers cable support systems fabricated from mild steel, corrosion-resistant steel, stainless steel and aluminium alloys as per customer requirement. Along with corrosion-resistant finishes, including zinc and epoxy coated.
MATERIAL
Steel – Hot Dip Galavanzed After Fabrication, used primarily for outdoor application. After the tray is made it is dipped into a molten zinc bath so that all surfaces are thoroughly coated, This provides excellent protection from the elements at an economical cost.
Steel – Mill Galvanized : Not generally recommended for outdoor use. Gives excellent service in dry or controlled atmospheres.
Steel – Stainless : Inherently corrosion resistant. Expensive.
FINISHES
Hot Dip Galvanizing
Hot dip galvanizing after manufacture is an excellent, economical protective finish used on support systems in many industrial and commercial applications. The galvanized coating is applied as a final manufacturing process by immersing a steel component (after various pre treatments) in a large bath of molten zinc; the zinc form an alloy with the steel substrate and protects the steel from corrosion in two ways.
Hot dip galvanized after completed manufacture to the requirements of BS729 or equivalent.
Specification
BS 719;1971 Hot Dip galvanized on Iron and Steel Articles.
Coating Weight:
| Category | Minimum average coating weight for any individual test area (in g/m2) | |
|---|---|---|
| Steel ricles | 5mm thich and cover | 610 |
| which are not centrifugal | Under 5mm but not less than 2mm | 460 |
| Under 5mm but not less than 1mm | 335 | |
| Grey and malleable iron castings Threaded work and other articles which are centrifuged | 610 305 |
|
Epoxy Coated
Epoxy coatings are based on thermosetting epoxy resins and give a very hard, durable finish suitable for internal applications. Epoxy coatings have good chemical resistance with excellent adhesion and coating flexibility.
Fore-Sight offers a wide selection of materials and finishes to meet your demanding environment conditions.
The Benefits of Cable Tray / Cable Ladder
Cable tray / Cable ladder wiring system offer significant advantages over conduit pipe and other wiring systems. Cable tray is less expensive, more reliable, more adaptable, to changing needs and easier to maintain. In addition, its design does not contribute to potential safety problem associated with other wiring systems.
SELECT THE CABLE LADDER CLASS
NEMA standard VE-1 defines 12 loads classes. The classes are designated by a number (8,12,16 and 20), specifying maximum span in feet and a letter (A,B and C), specifying maximum span in feet and a letter (A,B and C), specifying maximum load (A=50lbs./ft., B=75lbs./ft. and C=100lbs./ft.). The load rating must include the weight of the cables plus any applicable of the cables plus and applicable wind or snow loads. The load capacity available for cable is therefore reduced for outdoor applications.
BS2989, BS729, BS EN10142
Four support span categories for cable ladder:
8 = 8ft
12 = 12ft
16 = 16ft
20 = 20ft
These basic working load categories:
A = 50lbs / linear ft
B = 75lbs / linear ft
C = 100lbs / linear ft
NEMA Table
Load / Span Designations
| Class Designation | Support Span Feet | Working Load Lbs / Linear Foot |
|---|---|---|
| 8A 8B 8C | 8 8 8 | 50 75 100 |
| 12A 12B 12C | 12 12 12 | 50 75 100 |
| 16A 16B 16C | 16 16 16 | 50 75 100 |
| 20A 20B 20C | 20 20 20 | 50 75 100 |
(Quoted from NEMA VE1 Specification)
Note: In the interest of continuous improvements, Fore-Sight reserves the right without prior notice to alter the design and specifications of their products.
