Abstract: Conduit spacers useful in preparing duct banks are disclosed. The conduit spacers are designed for attachment to each other in vertical and horizontal combinations, that is, they may be arranged in side-by-side arrays, up-and-down arrays, or arrays that are both side-to-side and up-and-down. Thus, the conduit spacers include both vertical and horizontal restraints or interlocks. The vertical interlocks are achieved by the use of tapered tabs and tapered slots, both the tabs and the slots having tapers in the same horizontal direction. Horizontal interlocks are made by the use of rails and matching grooves in the sides of the spacers. Thus, both vertical and horizontal interlocks are achieved by assembling the ducts in a horizontal direction, side-by-side as desired for width, and up-and-down as desired for height. The number and length of conduits and the length of the duct banks needed dictate how many spacers are needed.