NEMA VE-2 states that metallic cable trays can be installed transversely (on their sides) but the NEC does not address this type of installation under 392. The manufacturers provide no structural or load ratings based on cable tray mounted on it’s side and only provide load data as per NEMA VE-1 which is tested on the horizontal orientation. It seems that NEC addresses cable fill based on a horizontal orientation for cross sectional fill. Flipping a full cable tray on it’s side places the bottom cables in a situation where heat dissipation could be much worse as those bottom cables could now be considered 2-20 cables deep. This of course also does not address any environmental loads that can be made worse by increasing the total area exposed to wind loads for which NEMA does not require manufacturers to provide for this orientation. So how does one apply the NEC code to a transverse installation and why doesn’t the NEC address this at all?