![]() ![]() Your chillers should be hooked up with electrical plugs and hydraulic quick connects so that you can swap in a spare chiller. You will need chillers at each end and you should use a total of 6 cooling circuits, 2 for each row with a total 12 chillers. polybutylene tubes that form 2 cooling circuits in each conduit. Your ducts are theoretically big enough to contain four 0.625 inch O.D. This ONLY applies to the part that has no more than 4 feet of dirt on top.īecause of the deep portion and because of the puny capacity of each cable, you need artificial cooling. For 15 ducts you MUST use concrete encasement because that is the only kind of backfill that will not break the ducts and you need the thermal conductivity of the concrete. Since for 6 or more ducts the main thermal bottleneck you can figure 500 KCM at 168.75 amps per cable for natural cooling. In Annex B of National Electrical Code there is a 15 duct bank that uses 2,000 KCM conductors. William RE: Electrical Duct Bank Calcs cuky2000 (Electrical) 10 Mar 05 14:24 To figure Vd for a given wire size, use a worst-case power factor (I use 0.7) and the corresponding X and R values from table 9. Find the required wire size from the value in the proper column in the proper table. Divide the ampacity of the wire determined in step 1 by each of the derating factors in turn to get a final ampacity requirement ģ. Figure a minimum wire size for a maximum Vd (I use 3% for feeders) at full load amps Ģ. You don't exactly "derate" for voltage drop. Don't forget that the conductor jacket temperature rating cannot exceed the temperature rating of the conduit (usually 90 deg C, so MV-105 is out for PVC). If medium voltage, you also need to derate for induced shield currents. If medium voltage, go to B.310-77 or somewhere close by. Use ambient derating factors at the bottom of the table, also. You did not indicate the system voltage, ampacity, and number of circuits, but assuming you are at 480 VAC, then table B.310-7 includes different colums for derateing based on the number of circuits. The code book says that is good for 90% of USA. Please contact us for more information.I would use rho = 90 as a starting point. ![]() With Cal Am Duct Spacers, contractors can save installation time and reduce costs while ensuring the accurate separation of ducts.Īvailable in pre-assembled configurations. In addition, the spacers are environmentally friendly, made from recycled materials, and recyclable. Their lightweight design makes them easy to handle and transport. The ease of assembly and resistance to soil conditions and extreme temperatures make Cal Am Duct Spacers a trusted choice for contractors. Overall, Cal Am Duct Spacers are a reliable and cost-effective solution for any duct placement project. Offering an extensive range of sizing means Cal Am spacers can be tailor-fit to any project-big or small. These sturdy, versatile spacers will not shift under the weight of your workmen and stay firmly in place during fill.Īvailable in eighteen (18) sizes, Cal Am Duct Spacers accommodate ducts ranging in size from 2.00” – 8.00” | 50mm – 200mm while providing duct separation of 1.50” – 3.00” | 40mm – 80mm. They utilize a proven two-piece design precisely engineered to support duct arrays within trenching before encasement. Vertical and horizontal interlocking duct spacers for fast secure field assemblyĬal Am Duct Spacers have been the choice for contractors for decades. ![]()
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