Concrete encased duct bank size free#

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.)/Contents()/BS/Rotate 90/AP/NM(OAEBCZONHQXBRYFQ)>ħ 0 obj>/Matrix/Length 151> 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 If using Reinforced concrete, or reinforced cement concrete (RCC) the clearance it is 3'. All duct bank construction instruction includes this: 16.7 Minimum concrete encasement shall be 3' on top, bottom and sides of conduit. 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. Electrical Engineer Power Station Physical Design Retired. *Refer to 310.15 for the ampacity correction factors where the ambient temperature is other than 40☌ (104☏).

Concrete encased duct bank size free#

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) **Refer to 240.4(D) for conductor overcurrent protection limitations. *Refer to 310.15 for the ampacity correction factors where the ambient temperature is other than 30☌ (86☏). 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. 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. Table B.2(11) provides the adjustment factors for more than three current-carrying conductors in a raceway or cable with load diversity. Typical ampacities for conductors rated 0 through 2000 volts are shown in Table B.2(1) through Table B.2(10).