Do not use a cable tray as a walkway ladder or support for people.
Cable ladder support span calculation.
However in practice a run must contain joints and it can also never be of infinite length so it is important to appreciate how its characteristics vary from span to span and how these.
Expansion splice plates.
Cable tray is a mechanical support system for cables and raceways.
Support of cable tray and ladder is typically.
And load figures inclusive of a safety factor of 1 7.
Support points are often trapezes suspended from threaded rod cantilever brackets or other strut systems.
Quick tray wire mesh cable tray fill table at 50.
L intermediate span f deflection 1 100 of the intermediate span max s splice location.
Cable load working load the cable load or the working load is the total weight of the cables to be placed in the tray.
The span length from the support.
The nema classes are based on cable loads of 50 75 and 100 per lineal foot.
6 cable ladder and cable tray systems including channel support systems and other associated supports definitions and abbreviations accessory component used for a supplementary function e g.
Using cable trays as walkways can cause personal injury and also damage cable tray and installed cables.
For support spans greater than 5 feet 1 5m cable loads must be evaluated to ensure that the span between the supports is suitable for the load the support and anchor must be evaluated separately.
610mm of a splice on straight sections and the span between supports should not exceed the length of tray.
To ensure adequate support accessories should be supported locally.
This classification is based on the working load the total weight of the cables and the support span the distance between supports.
In the case of electrical products such as cable tray or ladder which are load rated in kilograms per metre the span is the distance between support points separate from the overall length of the tray or ladder itself.
In practical terms this covers continuous multi span installations evenly loaded along the length of and across the full width of the tray.
Unistrut s load and deflection figures are in accordance with cei iec 61537 2001 with the characteristic deflection of unistrut cable ladder limited to span 100.
Temperature when installing cable ladders 20 ºc calculations temperature differential 40 ºc expansion of stainless steel for this temperature range 0 69 mm m expansion coupler gap when installing including safety factor 15 0 mm.
Supports should be placed within 24 in.
Unistrut s load testing is in accordance with cei iec 61537 2001.
A typical multi span cable ladder or cable tray installation behaves largely as a continuous beam.
The quick tray wire mesh cable tray fill table below shows the number of cables and the load in lbf lineal foot developed by typical 4 pair and 6 pair cable weighing 20 lb kft and 40 lb kft respectively while this table is a useful guide actual loads must be calculated using the cable specified.
