NEMA 2 – NEMA STANDARD CABLE TRAY & LADDER

Section 6

Application Information

6.1 Deflection

Under normal applications deflections limitaions should not be included in design critera for cable trays.However,if unusual or special conditions exsist ,the manufacture should be consulted. Limatations of deflection for asthetic purpose only can result in an overdesigned tray system.

6.2 Concentrated static load (if required by user)

A concentrated static load is not included in Table 3.1,load span designations.Some user applications may require that a given concentrated state load may be imposed over and above the working load.Such a concentrated static load represents a static weight aapplied between the side rails at mid span. When so specified the concentrated static load may be converted to a equivalent,uniform load (W) in pounds per linear foot (kilograms per meter) using the formula.

W-2x(Concentrated Static Load)

Span length, ft (m)

and added to the static weight of cables in the tray . This combined load may be used to select a suitable load/ span designation. (see table 3-1, the manufacture should be consulted.

6.3 WARNINGS ! Walkways

In as much as cable tray is designated as a support for power or control cables, or both, and is not intended or designed to be a walkway for personnel,the user is urged to display appropiate warnings cautioning against the use of this support as a walkway.The following language is suggested:

Warning:Not to be used as a walkway,ladderor support for personnel.To be used only only as a mechanical support for cables and tubing.

6.4 Fittings

Changes in direction should be mechanically continuous and accomplished by use of fittings having dimensions in accordance with 2.3