Working (Allowable) Load Capacity:
REFERENCE: NEMA FG-1 (current issue)
The working (allowable) load capacity represents the ability of a fiberglass cable tray to support the static weight of cables. It is equivalent to the destruction load capacity, as determined by testing in accordance with paragraph 4.1, with a minimum safety factor of 1.5.

Concentrated Static Load (if required by User):
A concentrated static load is not included in the table above.

Some user applications may require that a given concentrated static load be imposed over and above the working load.

Such concentrated static load represents a static weight applied between the side rails at midspan. When so specified, the concentrated static load may be converted to an equivalent load (W_e) in pounds per linear foot (kg/m) using the formula:

2 x (Concentrated Static Load)
W_e = ------------------------------------------------------------------------------------------------------------------------------------------
Span length (feet or m)

and added to the static weight of cable in the tray.

This combined load may be used to select a suitable load/span designation (table above). If the combined load exceeds the working load shown, the manufacturer should be consulted.