Cable Types: Only use conductors rated for open-air environments, such as Tray Rated (Type TC) or Metal-Clad (Type MC) cables. Installing conduit on roofs requires careful attention to weatherproofing, load considerations, and code compliance to protect people and property. This guide explains the key code requirements, material choices, installation practices, and inspection steps to keep rooftop conduit installations. In this installment of our Code Corner series, Ryan Mayfield focuses on the 2023 National Electrical Code (NEC) changes concerning cable trays, particularly section 690. Historically, the NEC has allowed cable trays, but has lacked specific guidelines for sizing conductors and using smaller. Recognize electrical cable tray misuse that can lead to electric shock and arc-flash/blast events and fires caused by overheating. The use and installation of cable trays is covered by legally enforceable OSHA regulations in 29 CFR 1910. Here's what you need to know: Cable Types: Only use.
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