Expansion loops are required where the potential for stress exists. For an expansion loop to be effective, it must be correctly formed and installed. Each loop must be formed according to specifications whose criteria will produce precise bend radii and bottom lengths within the loop. It is crucial that the installer know where to place the loop, the correct forming equipment to use, how to use the equipment and finally how to secure the newly formed expansion loop. To prevent damage, expansion loops are located before and after each fixture to allow for cable movement.
Large cables require a larger bend radius within their loops than smaller cables.
Large cables also require longer loop bottoms than smaller cables. The reason for having two different sizes of expansion loops is to allow both small and large cables to safely move within their recommended bend radii. There are currently two lengths of expansion loops in use. One is for cables with a diameter of 0.75 inch or less, and the other is for cables with diameters larger than 0.75 inch. An expansion loop can be formed using either a mechanical bender or a bender board.