Cable Ampacity in Tray with Raised Covers

Power cable tray systems in generating stations are installed with tray covers that may be raised over the tray side rail. Raising the tray cover allows installation of the cover without cutting and fitting the cover around conduits that terminate at the tray. There is no industry standard or guidance for calculation of cable ampacity in trays with raised covers. The heat transfer literature is reviewed in this paper and the results of the review are incorporated in a method for calculation of cable ampacity in raised cover tray. Calculations are presented that show that cable ampacity with raised covers is approximately two percent greater than cable ampacity with covers installed directly on the tray side rails.