Indoor cable trays may have joints

Yes, indoor cable trays can have joints, typically in the form of splice plates or expansion joints, to accommodate length, structural connections, and thermal movement.Types of Joints in Cable TraysSplice Plates: Cable trays are often joined using splice plates, which connect two tray sections mechanically and electrically. These plates ensure continuity of the tray while maintaining structural integrity and proper grounding when bonding jumpers are installed across the joint . Expansion Joints: In longer runs, especially where temperature variations may cause thermal expansion or contraction, expansion joints are used. These joints allow the tray to expand or contract without distortion, bending, or bolt hole elongation. Expansion joints are typically installed at building movement points or where structural expansion occurs, and bonding jumpers with sufficient slack are required to maintain electrical continuity .Installation ConsiderationsSupport Placement: Supports should be located close to joints, usually within 2 feet of each side of a splice or expansion joint, to prevent sagging and allow proper movement .Anchoring and Guides: The tray should be anchored at the midpoint between expansion joints, with expansion guides at other supports to allow sliding during thermal changes .Material and Length: The frequency of expansion joints depends on the tray material and expected temperature differential. For example, steel trays may require an expansion joint every 128 feet for a 100°F temperature change, while aluminum trays may require one every 65 feet .Electrical SafetyAll joints must maintain proper bonding to ensure electrical safety. Bonding jumpers across joints are critical to prevent potential hazards and maintain grounding continuity . Improper bonding or missing expansion joints can lead to system damage, sagging, or electrical faults.SummaryIndoor cable trays do have joints, which serve both mechanical and electrical purposes. Proper installation of splice plates, expansion joints, supports, and bonding jumpers ensures structural integrity, accommodates thermal movement, and maintains electrical safety .