Annex B Application Information for Ampacity Calculation
Annex B Application Information for Ampacity Calculation
Annex B Application Information for Ampacity Calculation
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<strong>Annex</strong> B: AmpacitiesANNEXBTable B.310.3 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°C (104°F)(For Types TC, MC, MI, UF, and USE Cables)Temperature Rating of Conductor. (See Table 310.13.)Size (AWGor kcmil)6O°C(140°F)7S o C 8S o C(167°F) (18S 0 F)COPPER90°C(194°F)60°C 7S o C 8S o C 9O°C(140°F) (167°F) (18S 0 F) (194°F)ALUMINUM OR COPPER·CLAD ALUMINUMSize (AWGor kcmil)18161412108--18*21*28*39--21*28*36*50--24*30*41*5611*16*25*32*43*59---18*21*30---21*28*39---24*30*44---25*32*4618161412108643215269819210768891041181387510011613215479104121138161415463728453708192108597891103120618195108126643211/02/03/04/0124143165190160184213245178206238274186215249287971111291491251441661921391601852141451681942241/02/03/04/025030035040050021223726128132127430633736341630534137740646532035739442548716618620522225521424026528733023926829631736825028030933438525030035040050060070075080090010003543874044154384614595025235395706015135625866046396745385896156336707072843063283393623853684054244394694994104624734905145584294734955135485846007007508009001000Correction FactorsAmbient For ambient temperatures other than 40°C (104°F), AmbientTemp. multiply the ampacities shown above Temp.("C) by the appropriate factor shown below. (oF)21-25 1.32 1.20 1.15 1.14 1.32 1.20 1.15 1.14 70-7726-30 1.22 1.13 1.11 1.10 1.22 1.13 1.11 1.10 79-8631-35 1.12 1.07 1.05 1.05 1.12 1.07 1.05 1.05 88-9536-40 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 97-10441-45 0.87 0.93 0.94 0.95 0.87 0.93 0.94 0.95 106-11346-50 0.71 0.85 0.88 0.89 0.71 0.85 0.88 0.89 115-12251-55 0.50 0.76 0.82 0.84 0.50 0.76 0.82 0.84 124-13156-60 - 0.65 0.75 0.77 - 0.65 0.75 0.77 133-14061-70 - 0.38 0.58 0.63 - 0.38 0.58 0.63 142-15871-80 - - 0.33 0.44 - - 0.33 0.44 160-176'Unless othelWise specifically permitted elsewhere in this Code, the overcurrent protection <strong>for</strong> these conductortypes shall not exceed 15 amperes <strong>for</strong> 14 AWG, 20 amperes <strong>for</strong> 12 AWG, and 30 amperes <strong>for</strong> 10 AWG copper;or 15 amperes <strong>for</strong> 12 AWG and 25 amperes <strong>for</strong> 10 AWG aluminum and copper-clad aluminum.70--692NATIONAL ELECTRICAL CODE2008 Edition
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