Generally used in applications with intermediate to long support spans 12 to 30
feet.A ladder cable tray without covers permits the maximum free flow of air
across the cables. This allows the heat produced in the cable’s conductors to
effectively dissipate. Under such conditions, the conductor insulation in the
cables of a properly designed cable tray wiring system will not exceed its
maximum operating temperature.
The rungs of the ladder cable trays provide convenient anchors for tying down
the cables in the non-horizontal cable tray runs or where the positions of the
cables must be maintained in the horizontal cable tray runs. This capability is
a must for single conductor cable installations. Under fault conditions (short
circuit), the magnetic forces produced by the fault current will force the
single conductor cables from the cable tray if they are not securely anchored to
the cable tray.
Cables may exit or enter the ladder cable trays through the top or the bottom of
the cable tray. Where the cables enter or exit conduit, the conduit to cable
tray clamps may be installed upright or inverted to terminate conduits on the
top or bottom of the cable tray side rail.
The most common rung spacing for ladder cable tray is 9 inches. This spacing may
be used to support all sizes of cables.