Page 65 - Unistrut-Australia Catalog
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                                                                                  NEMA CABLE LADDER - STEEL
STEEL CABLE LADDER (SCL)
Galvanised steel cable ladders are the most popular format for cable support systems as they afford a good combination of cost, strength and service life. Unistrut® manufactures a complete range of NEMA Steel Cable Ladder systems. These systems provide a wide range of load and span combinations to suit the requirement of almost any installations.
Side-Rail Alternative - With the exception of Nema 12B, all other ladder systems are available with the side-rails turned outward (as standard), or inward to meet varying client specifications.
All ladder systems are load rated to NEMA Standard VE 1.
Stainless Steel - In cases where extremely high corrosion resistance is required, stainless steel cable ladder may be the only solution. All steel cable ladder systems are available in stainless steel on special order only. For load and deflection calculations, contact your local Unistrut® Service Centre.
SPLICE PLATES
16A, 20B and 20C Systems - Unistrut® steel splice plates are of a robust and practical design. The neat fitting flanges and bolted configuration of Unistrut® splices also reduce deflection at joints as the ladder is loaded. Unsightly dips or discontinuities along the ladder run are therefore avoided. Bolt holes in splice plates and ladder side-rails are elongated so that site misalignments as well as thermal expansion and contraction are catered for.
12B Systems - The 12B splice plate incorporates virtually all of the working features as described for the 16A, 20B and 20C ladders, but because the 12B is a lighter duty system, a simplified splice design is used.
Requiring only two fixing bolts and eliminating the need for matching holes in the side-rail, the 12B splice plate is convenient in use and extremely fast to install.
Notes
Electrical resistance across splice joints is less than the 330 micro-ohms limit specified by NEMA Standard VE 1. To attain maximum working load of the system, the following recommendations should be adopted.
• Do not splice single spans of ladder.
• Avoid splice joints in the vicinity of the end supports on continuous runs.
• Avoid splice joints directly over intermediate supports on continuous runs.
• Locate splice joints at the quarter span point between supports on continuous runs.
If in doubt, please consult your Unistrut® Service Centre.
ACCESSORIES
All Unistrut® steel cable ladder systems are complemented by a full range of standardised fabricated accessories and fittings which are readily available. All are of a welded construction.
Built-in Splice - The principal feature of all Unistrut® cable ladder accessories is the ‘built-in’ splice plate. A shaped extension of the accessory side-rail permits direct connection to the straight ladder eliminating the need for a separate splice component.
The advantages of this method are:
• Minimised fixing hardware and components.
• When joining to a cut ladder, the accessory end acts as a convenient drill template for bolt holes. • Simplifies pre-planning, quantity take-offs and ordering.
• No left-over components.
• Strong and rigid joint.
• Faster installation.
Accessories are attached with the same fasteners as used for straight splice plates. Threaded fasteners are hot dipped galvanised.
Elongated slots allow easier fit-up and permit adjustments in alignment to be absorbed.
CONSTRUCTION
Unistrut® steel cable ladders are manufactured from steel to AS/NZS1594 “Hot-Rolled Steel Flat Products,” which are cold roll formed to the desired shape. The roll forming process improves the mechanical properties of the metal whilst the special lipped strut section is designed to give the best possible combination of strength-to-weight, lateral rigidity and low deflection. The rungs are fillet welded to the side-rails which further improves the overall stability as well as strength of the finished product. The rung joint is so designed that galvanising can be effected to all areas.
Ladders, accessories and other galvanised components are hot-dipped galvanised to AS/NZS 4680 / BS EN ISO 1461 after fabrication.
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            NEMA CABLE LADDERS
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