Normally, the bare copper is brought up above the finish grade and a five foot pigtail is coiled up for future connection to building column, equipment, or whatever you are trying to hit. But these are expensive and a pain in the neck to form and keep in place when pouring the slab or deck. The calculator lets you know the amount of dirt to remove, the amount of dirt to return, the amount of concrete for a duct bank, and the amount of left over dirt. In simplest terms, a duct bank provides a protected pathway for buried electrical or data cables. Calculates the duct bank size based on the quantity of conduits, the size and type of conduit. The biggest problem is probably physical damage to the ground conductor during construction.Įrico and others make flush grounding pads that you can install to allow a bolted connection to the ground pad. Construction Type & Installation Methods. ![]() Moist concrete is a reasonable conductor - a lot better than you might expect. The corrosion engineers I've worked with don't seem to get too worked up about putting bare copper directly in concrete. conduits with 3 600 MCM conductors are required to feed the 4,000-amp load. Once again, the load factor is reduced from 100 to 75 and the RHO of the concrete around the duct bank is reduced from 90 to 75. ![]() If anything, you might get some galvanic action that reduces the iron in the rebar, but that is generally not a problem unless you have a constant dc potential on the ground grid wrt to the remote earth. The hand calculations become even more complex if cable in the duct bank are of different sizes. Reinforced concrete is reasonably compatible with bare copper. By modeling these sections in appropriate combinations (single, side-by-side, and/or stacked), design teams can speed the planning, initiation, and completion of the most complex duct bank systems. It's done all the time for Ufer grounds as well as connections to embedded ground grids, etc. Specify Type DB PVC conduit for concrete encased duct banks. precast duct bank sections, in standard configurations featuring 1H x 2W to 5H X 5W conduits per section.
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