I asked before about installation of power and control cable in the same conduit .. I think it is not a good practice.. I want to ask about installing 2 power cable each 480V in the same conduit ..Also I want to know if it is mentioned in any standard like NECthx
Article 725 of NFPA 70 (the NEC) should answer your questions regarding Class 1, 2 3 Remote-Control, Signaling, and Power-Limited Circuits and the installation requirements that apply to your specific application.
You can as long as every cable in the raceway is insulated at least for the maximum voltage in the raceway. NEC 300.3 (C) (1). You also need to consider raceway fill limits, and ampacity derating for 4 or more current carrying conductors.
