As per NEMA VE 1, Metal Cable Tray Systems, cable tray typical lengths, not including connectors, are:
(a) 3m ± 5mm (10 ft ± 3/16 in.);
(b) 3.66m ± 5mm (12 ft ± 3/16 in.);
(c) 6m ± 9mm (20 ft ± 5/16 in.); and
(d) 7.32m ± 9mm (24 ft ± 5/16 in.).
Actual[……]