Types of Expansion Joints (Structural Details) Three common constructions are used in the industry: Inner tray section is one size smaller, sliding inside the outer tray. 1993 NEC Section 300-7 (b) states that “Raceways shall be provided with expansion joints where necessary to compensate for the thermal expansion or contraction. As cables and trays expand or contract, they can cause stress on the structure, leading to potential damage or misalignment. To mitigate these risks. Below is the detailed cable tray installation method statement not only for cable tray but also applicable for GI ladder and trunking for indoor and outdoor applications and in service rooms like pump rooms, electrical rooms and plant rooms etc. We aim to ensure your project remains secure and does not breach the NEMA standards, causing it to suffer. association representing the major electrical equipment manufac-turers in the U. The Cable Tray ng standards, performance standards, test standards and application in this document have been tested extens ompetent professional en completely installed, without damage either to conductors or.