![]() The new buildings will support over 70 local, family-owned businesses, including a variety of amenities. Table B.2(7) Ampacities of Three Single Insulated Conductors, Rated 0 Through 2000 Volts, in Underground Electrical Ducts (Three Conductors per Electrical Duct) Based on Ambient Earth Temperature of 20☌ (68☏), Electrical Duct Arrangement in Accordance with Figure B.Knelsen’s Precast division is proud to have been selected as the supplier of precast wall panels, featuring various architectural finishes, for the new Calgary Farmers Market building located in the northwest community of Greenwich. Table B.2(6) Ampacities of Three Insulated Conductors, Rated 0 Through 2000 Volts, Within an Overall Covering (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct) Based on Ambient Earth Temperature of 20☌ (68☏), Electrical Duct Arrangement in Accordance with Figure B.2(1), Conductor Temperature 75☌ (167☏) Size (AWG or kcmil)ġ Electrical Duct Table B.2(5) Ampacities of Single Insulated Conductors, Rated 0 Through 2000 Volts, in Nonmagnetic Underground Electrical Ducts (One Conductor per Electrical Duct), Based on Ambient Earth Temperature of 20☌ (68☏), Electrical Duct Arrangement in Accordance with Figure B.2(1), Conductor Temperature 75☌ (167☏) Size (kcmil)ģ Electrical Ducts Ħ Electrical Ducts ĩ Electrical Ducts Ħ Electrical Ducts Fig. *Refer to 310.15 for the ampacity correction factors where the ambient temperature is other than 40☌ (104☏). Table B.2(3) Ampacities of Multiconductor Cables with Not More Than Three Insulated Conductors, Rated 0 Through 2000 Volts, in Free Air Based on Ambient Air Temperature of 40☌ (104☏) (for Types TC, MC, MI, UF, and USE Cables)* Size (AWG or kcmil) Existing underground duct banks and other utilities had to be either suspended in place or removed and replaced. The number of conduits within the duct bank lines ranged from 3 to 36. Duct bank design is an exercise in thermal analysis. ![]() **Refer to 240.4(D) for conductor overcurrent protection limitations. forming and pouring of encasement concrete and subsequent backfilling with 1 and 2 sack slurry. Hydro Ottawa primary cable shall be placed in 100 mm PVC DB2 duct that is either encased in reinforced concrete or direct buried, as specified in the Hydro Ottawa design. *Refer to 310.15 for the ampacity correction factors where the ambient temperature is other than 30☌ (86☏). Installation of Ducts and Cables All concrete encased, steel reinforced duct banks shall be installed as per Hydro Ottawa Engineering Specification No. Types THHN, THHW, THW-2, THWN-2, RHH, RWH-2, USE-2, XHHW, XHHW-2, ZW-2 Table B.2(1) Ampacities of Two or Three Insulated Conductors, Rated 0 Through 2000 Volts, Within an Overall Covering (Multiconductor Cable), in Raceway in Free Air Based on Ambient Air Temperature of 30☌ (86☏)* Size (AWG or kcmil) For additional information concerning the application of these ampacities, see IEEE STD 835, Standard Power Cable Ampacity Tables. These ampacities were calculated as detailed in the basic ampacity paper, AIEE Paper 57-660, The Calculation of the Temperature Rise and Load Capability of Cable Systems, by J. In Figure B.2(1) through Figure B.2(4), where adjacent duct banks are used, a separation of 1.5 m (5 ft) between the centerlines of the closest ducts in each bank or 1.2 m (4 ft) between the extremities of the concrete envelopes is sufficient to prevent derating of the conductors due to mutual heating. The thermal resistivity of concrete in the duct bank can be measured if a sample can be taken, or calculated if the concrete mixture used in the duct bank is known 6. Underground electrical duct bank configurations, as detailed in Figure B.2(2), Figure B.2(3), and Figure B.2(4), are utilized for conductors rated 0 through 5000 volts. ![]() The rebars shall be epoxied into the holes and extend at least 3 feet 6 inches into the duct bank encasement. Holes shall be drilled into the MHs to a depth of half that of the wall thickness. 2.2.4 Where duct banks tie into MHs, install a minimum of four 5 rebars to prevent shearing. Table B.2(11) provides the adjustment factors for more than three current-carrying conductors in a raceway or cable with load diversity. concrete below, on the sides, and above the bank of conduits. ![]() Typical ampacities for conductors rated 0 through 2000 volts are shown in Table B.2(1) through Table B.2(10).
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