Yes, it is legal to run the following cables in the same conduit

600V, 19-conductor #10 tray cable 2- 300V Belden cables

Conduit Requirements

Ensure the conduit is sized correctly to accommodate all the cables. Use Table 1, Chapter 9, of the NEC for conduit fill calculations. The conduit should be properly supported and protected from physical damage. Conductors should be secured within the conduit to prevent movement.

Voltage Rating Considerations

The 600V tray cable and the 300V Belden cables have different voltage ratings. The conduit must be rated for the highest voltage present, which is 600V in this case.

Other Considerations

Make sure the Belden cables are rated for use in the same environment as the tray cable.* Refer to the NEC and local codes for specific requirements and guidance on conduit installation.

Note: The answer assumes that the conduit is installed in accordance with the NEC and applicable local codes. Flag for review