Code Change Summary: New code section with requirements for expansion splice plates in a cable tray.

In the 2020 NEC^® a public input (code change proposal) was accepted to add requirements for thermal expansion and contraction in a spliced cable tray. There are no specific measurements or calculations provided in the NEC^® to determine if or how many expansion splice plates are required but the installation instructions for the cable tray should provide guidance.

Another helpful document is NEMA Publication VE 2-2013 Cable Tray Installation Guidelines. According to the document, there are four basic types of cable tray connectors including rigid, expansion, adjustable, and reducer. In the NEMA document, table 3.2 provides the Maximum Spacing between Expansion Joints that Provide for 250 mm (1 in) Movement. Additionally, the document states:

“Special hardware is supplied with expansion splice plates. The nuts may have a stopping device (plastic stop nut). Important: For plastic stop nut designs, tighten hardware, then loosen 1/2 turn”.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC^® edition of NFPA 70.