Abstract: Methods and devices for reducing stress and for increasing the load-hearing capacity of cable racks supporting electrical power and communication conduits and cables having increased versatility for conduit and cable sizes and quantities. Underground devices including rack arms for these applications are desirably made from plastic or composite materials. Rack arms desirably include openings for tying down the conduits and cables atop the arms. While non-metallic materials are designed to withstand environmental stresses, they typically have strength and rigidity properties less than the metallic structures previously used in such applications. Non-metallic rack arms with such openings may be reinforced locally with a stress attenuator or with ribs to increase their load-bearing and buckling capacity and to reduce their stress, strain and deflection under load. A stress attenuator may be made by increasing the in-molded thickness of the web in areas adjacent to or surrounding the tie-down openings.

Abstract: Methods and devices for reducing stress and for increasing the load-bearing capacity of cable racks supporting electrical power and communication conduits and cables having increased versatility for conduit and cable sizes and quantities. Underground devices including rack arms for these applications are desirably made from plastic or composite materials. Rack arms desirably include openings for tying down the conduits and cables atop the arms. While non-metallic materials are designed to withstand environmental stresses, they typically have strength and rigidity properties less than the metallic structures previously used in such applications. Non-metallic rack arms with such openings may be reinforced locally with a stress attenuator or with ribs to increase their load-bearing and buckling capacity and to reduce their stress, strain and deflection under load. A stress attenuator may be made by increasing the in-molded thickness of the web in areas adjacent to or surrounding the tie-down openings.

Abstract: Apparatuses and methods are disclosed for assembling ducts or conduits with multi-part spacers for underground installation. Sequential loading of conduits to multi-part spacers, as opposed to older methods of end loading, allows construction workers to easily assemble conduits to a plurality of multi-part duct spacers above-ground. The multi-part loading technique allows sequential loading of conduits into portions of spacers, the spacers having bores to accommodate the conduits. The parts or components of the multi-part spacers may themselves cooperate to mount conduits into a conduit bank or bundle. Thus, conduits are assembled or mounted to a first portion of the spacer, followed by mounting a second portion of the spacer and then additional conduits, which may be mounted to either or both of the first and second portions. Once assembled, the banks or bundles may then be secured with banding and wheeled into a protective casing.

Abstract: A duct bank is assembled and placed into a trench. A method for securing the duct bank uses hold-down bars extending horizontally atop the duct bank and securing rods embedded in the trench. A one-way retainer, such as a push nut, is placed into a counterbore of a hand installation tool. The hand installation tool is then used to place the push nut a fixed distance onto one end of a securing rod. After removing the hand tool from the rod, the rod is then placed through an orifice of the push down bar and is extended through the duct bank. The rod is then embedded into the trench until the hold-down bar deforms slightly. This procedure is then followed for each orifice of the hold-down bar and for each hold-down bar used to secure the duct bank. The trench may then be backfilled with concrete or flowable fill.

Abstract: A duct bank is assembled and placed into a trench. A method for securing the duct bank uses hold-down bars extending horizontally atop the duct bank and securing rods embedded in the trench. A one-way retainer, such as a push nut, is placed into a counterbore of a hand installation tool. The hand installation tool is then used to place the push nut a fixed distance onto one end of a securing rod. After removing the hand tool from the rod, the rod is then placed through an orifice of the push down bar and is extended through the duct bank. The rod is then embedded into the trench until the hold-down bar deforms slightly. This procedure is then followed for each orifice of the hold-down bar and for each hold-down bar used to secure the duct bank. The trench may then be backfilled with concrete or flowable fill.

Abstract: Conduit spacers useful in preparing duct banks with reduced electromagnetic fields (EMF) are disclosed. The conduit spacers are designed to maximize phase cancellation of EMF from a closely-spaced series of electric power cables placed in conduits supported underground by the conduit spacers. The spacers are also designed to minimize the EMF above ground by reducing the distance needed to bury the cables for a given EMF above ground. In one embodiment, the spacers place conduits adjacent one another for maximum cancellation of a single three-phase cable installation. In another embodiment, the spacers place conduits adjacent one another for maximum cancellation for a dual three-phase cable installation, including cross-phase cancellation, e.g., A-B-C and C-B-A.