How to Calculate the Fill of a Cooper B-Line Cable Tray

Determine the size and length of the cable you will be using. Because a cable tray is rated for specific size and length of cable, knowing your need is essential. Measure the span and cable thickness with a tape measure. The number of cables will depend on the number of circuits needed.

Measure the depth of the cable to be stacked into the tray to determine the depth of tray needed. For example, if your cable is 2 inches thick and you will stack it four deep in the tray, then you will need a 8-inch deep cable tray. However, cable thickness depends on the load of the circuit, as well.

Determine the width of the cable tray needed for 2-inch cable. For example, if you are going to place four 2-inch cables across in the tray, then you will need an 8-inch-wide tray to hold the cables.

Determine the cable tray depth and width for 1-inch cable by multiplying the number of cables to be laid across and stacked in the tray. For example, if you will stack two 1-inch cables four-wide in the tray, then you will need a tray measuring 2 inches deep and 4 inches wide.

Determine the length of the tray needed by considering cable weight. A normal cable tray can hold 50 pounds of cable for every 24 inches of tray length. For example, 2-inch cable weighs 20 pounds per 20 feet, or 1 pound per foot. Since 12 strands of cable 20 feet long will weigh 240 pounds, then your tray fill will hold the length of cable necessary for 20 feet.