A cable rack arm and support system suitable for underground power and communication service is made from reinforced non-metallic polymers that will not rust or corrode. A cable rack arm up to thirty inches long may be compression molded with long glass fibers in a polyester or vinylester matrix. Each cable rack arm is securely mounted to a non-metallic stanchion that may be made from a reinforced, pultruded composite material. Nonmetallic pins may be used to secure the cable rack arms to the stanchions. Each cable rack arm then supports one or more cables in cable saddles that are snap-fit atop the arm, thus keeping the cables accessibly organized in a manhole, tunnel or vault. Each saddle may include elastomeric dampening material to reduce shock and vibration in the mechanical and electrical environment in underground tunnels, vaults and manholes.