Use splice plates (couplers) on the sides to connect them. Insert the mushroom-head bolts from the inside of the tray pointing out (this protects cables from snagging on bolt threads) and tighten the nuts on the outside. This is a critical safety step. But before you lay the first tray or clamp down a single cable, you need a solid plan. The Double Splice cuts the required number of splice hardware down to a minimal number versus traditional splice kits, reducing labor and installation. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when the cable tray cont d for instrumentation and control applications that require. Here is a step-by-step guide on how to install a standard metal cable tray system (e.