National Electrical Installation Standards

Standards as High as Your Own

Monday, September 4, 2023


Hello CQD, a metal cable tray with a cover/lid, in a production line, what is the maximum cable filling percentage? Does it matter if the cable tray is integral to a machine? I would think there is no difference. Thank you, Uwe Hammerath


Hi Uwe, thank you for participating in the CQD. Section 392.22(A)-(C), including Tables, provides guidance on maximum fill percentage for Cable Trays. There are several variables in play based on wire or cable types, voltages etc. Regarding a Cable Tray that is integral to a machine, it would depend on the equipment listing and installation instructions. Typically, the standards that govern how listed electrical equipment is built and tested will align with the NEC® and so it would likely be the same fill percentage. If the Cable Tray integral to the electrical equipment seems to be overfilled, it may be worth checking with the manufacturer or the NRTL that lists the equipment.

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