{"data":{"id":"us/10-cfr-431.196","jurisdiction":"us","citation":"10 CFR 431.196","heading":"Energy conservation standards and their effective dates.","body":"(a) Low-Voltage Dry-Type Distribution Transformers. (1) The efficiency of a low-voltage, dry-type distribution transformer manufactured on or after January 1, 2007, but before January 1, 2016, shall be no less than that required for the applicable kVA rating in the table below. Low-voltage dry-type distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nSingle-phase Three-phase\nkVA % kVA %\n15 97.7 15 97.0\n25 98.0 30 97.5\n37.5 98.2 45 97.7\n50 98.3 75 98.0\n75 98.5 112.5 98.2\n100 98.6 150 98.3\n167 98.7 225 98.5\n250 98.8 300 98.6\n333 98.9 500 98.7\n750 98.8\n1000 98.9\nNote 1 to paragraph (a)(1):\nAll efficiency values are at 35 percent per-unit load.\n(2) The efficiency of a low-voltage, dry-type distribution transformer manufactured on or after January 1, 2016, but before April 23, 2029, shall be no less than that required for the applicable kVA rating in the following table. Low-voltage dry-type distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nTable 2 to Paragraph (a)(1)\nSingle-phase Three-phase\nkVA kVA\n15 97.70 15 97.89\n25 98.00 30 98.23\n37.5 98.20 45 98.40\n50 98.30 75 98.60\n75 98.50 112.5 98.74\n100 98.60 150 98.83\n167 98.70 225 98.94\n250 98.80 300 99.02\n333 98.90 500 99.14\n750 99.23\n1000 99.28\nNote: All efficiency values are at 35 percent of nameplate-rated load, determined according to the DOE Test Method for Measuring the Energy Consumption of Distribution Transformers under appendix A to this subpart K.\n(3) The efficiency of a low-voltage dry-type distribution transformer manufactured on or after April 23, 2029, shall be no less than that required for their kVA rating in the following table. Low-voltage dry-type distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nTable 3 to Paragraph (a)(3)\nSingle-phase Three-phase\nkVA Efficiency (%) kVA Efficiency (%)\n15 98.39 15 98.31\n25 98.60 30 98.58\n37.5 98.74 45 98.72\n50 98.81 75 98.88\n75 98.95 112.5 98.99\n100 99.02 150 99.06\n167 99.09 225 99.15\n250 99.16 300 99.22\n333 99.23 500 99.31\n750 99.38\n1000 99.42\nNote: All efficiency values are at 35 percent of nameplate-rated load, determined according to the DOE Test Method for Measuring the Energy Consumption of Distribution Transformers under appendix A to this subpart K.\n(b) Liquid-Immersed Distribution Transformers. (1) The efficiency of a liquid-immersed distribution transformer manufactured on or after January 1, 2010, but before January 1, 2016, shall be no less than that required for their kVA rating in the table below. Liquid-immersed distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nSingle-phase Three-phase\nkVA Efficiency (%) kVA Efficiency (%)\n10 98.62 15 98.36\n15 98.76 30 98.62\n25 98.91 45 98.76\n37.5 99.01 75 98.91\n50 99.08 112.5 99.01\n75 99.17 150 99.08\n100 99.23 225 99.17\n167 99.25 300 99.23\n250 99.32 500 99.25\n333 99.36 750 99.32\n500 99.42 1000 99.36\n667 99.46 1500 99.42\n833 99.49 2000 99.46\n2500 99.49\nNote 3 to paragraph (b)(1):\nAll efficiency values are at 50 percent per-unit load.\n(2) The efficiency of a liquid-immersed distribution transformer, including submersible distribution transformers, manufactured on or after January 1, 2016, but before April 23, 2029, shall be no less than that required for their kVA rating in the following table. Liquid-immersed distribution transformers, including submersible distribution transformers, with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nTable 5 to Paragraph (b)(2)\nSingle-phase Three-phase\nkVA Efficiency (%) kVA Efficiency (%)\n10 98.70 15 98.65\n15 98.82 30 98.83\n25 98.95 45 98.92\n37.5 99.05 75 99.03\n50 99.11 112.5 99.11\n75 99.19 150 99.16\n100 99.25 225 99.23\n167 99.33 300 99.27\n250 99.39 500 99.35\n333 99.43 750 99.40\n500 99.49 1000 99.43\n667 99.52 1500 99.48\n833 99.55 2000 99.51\n2500 99.53\nNote: All efficiency values are at 50 percent of nameplate-rated load, determined according to the DOE Test—Procedure, appendix A to this subpart K.\n(3) The efficiency of a liquid-immersed distribution transformer, that is not a submersible distribution transformer, manufactured on or after April 23, 2029, shall be no less than that required for their kVA rating in the following table. Liquid-immersed distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nTable 6 to Paragraph (b)(3)\nSingle-phase Three-phase\nkVA Efficiency (%) kVA Efficiency (%)\n10 98.77 15 98.92\n15 98.88 30 99.06\n25 99.00 45 99.14\n37.5 99.10 75 99.22\n50 99.15 112.5 99.29\n75 99.23 150 99.33\n100 99.29 225 99.38\n167 99.46 300 99.42\n250 99.51 500 99.38\n333 99.54 750 99.43\n500 99.59 1000 99.46\n667 99.62 1500 99.51\n833 99.64 2000 99.53\n2500 99.55\n3750 99.54\n5000 99.53\nNote: All efficiency values are at 50 percent of nameplate-rated load, determined according to the DOE Test Method for Measuring the Energy Consumption of Distribution Transformers under appendix A to this subpart K.\n(4) The efficiency of a submersible distribution transformer, manufactured on or after April 23, 2029, shall be no less than that required for their kVA rating in the following table. Submersible distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nTable 7 to Paragraph (b)(4)\nSingle-phase Three-phase\nkVA Efficiency (%) kVA Efficiency (%)\n10 98.70 15 98.65\n15 98.82 30 98.83\n25 98.95 45 98.92\n37.5 99.05 75 99.03\n50 99.11 112.5 99.11\n75 99.19 150 99.16\n100 99.25 225 99.23\n167 99.33 300 99.27\n250 99.39 500 99.35\n333 99.43 750 99.40\n500 99.49 1000 99.43\n667 99.52 1500 99.48\n833 99.55 2000 99.51\n2500 99.53\nNote: All efficiency values are at 50 percent of nameplate-rated load, determined according to the DOE Test—Procedure, appendix A to this subpart K.\n(c) Medium-Voltage Dry-Type Distribution Transformers. (1) The efficiency of a medium-voltage dry-type distribution transformer manufactured on or after January 1, 2010, but before January 1, 2016, shall be no less than that required for their kVA and BIL rating in the table below. Medium-voltage dry-type distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nSingle-phase Three-phase\nkVA BIL* kVA BIL\n20-45 kV 46-95 kV ≥96 kV 20-45 kV 46-95 kV ≥96 kV\nEfficiency (%) Efficiency (%) Efficiency (%) Efficiency (%) Efficiency (%) Efficiency (%)\n15 98.10 97.86 15 97.50 97.18\n25 98.33 98.12 30 97.90 97.63\n37.5 98.49 98.30 45 98.10 97.86\n50 98.60 98.42 75 98.33 98.12\n75 98.73 98.57 98.53 112.5 98.49 98.30\n100 98.82 98.67 98.63 150 98.60 98.42\n167 98.96 98.83 98.80 225 98.73 98.57 98.53\n250 99.07 98.95 98.91 300 98.82 98.67 98.63\n333 99.14 99.03 98.99 500 98.96 98.83 98.80\n500 99.22 99.12 99.09 750 99.07 98.95 98.91\n667 99.27 99.18 99.15 1000 99.14 99.03 98.99\n833 99.31 99.23 99.20 1500 99.22 99.12 99.09\n2000 99.27 99.18 99.15\n2500 99.31 99.23 99.20\n* BIL means basic impulse insulation level.\nNote 5 to paragraph (c)(1):\nAll efficiency values are at 50 percent per-unit load.\n(2) The efficiency of a medium-voltage dry-type distribution transformer manufactured on or after January 1, 2016, but before April 23, 2029, shall be no less than that required for their kVA and BIL rating in the following table. Medium-voltage dry-type distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nTable 9 to Paragraph (c)(2)\nkVA Single-phase kVA Three-phase\nBIL 1 BIL\n20-45 kV 46-95 kV ≥96 kV 20-45 kV 46-95 kV ≥96 kV\nEfficiency (%) Efficiency (%) Efficiency (%) Efficiency (%) Efficiency (%) Efficiency (%)\n15 98.10 97.86 15 97.50 97.18\n25 98.33 98.12 30 97.90 97.63\n37.5 98.49 98.30 45 98.10 97.86\n50 98.60 98.42 75 98.33 98.13\n75 98.73 98.57 98.53 112.5 98.52 98.36\n100 98.82 98.67 98.63 150 98.65 98.51\n167 98.96 98.83 98.80 225 98.82 98.69 98.57\n250 99.07 98.95 98.91 300 98.93 98.81 98.69\n333 99.14 99.03 98.99 500 99.09 98.99 98.89\n500 99.22 99.12 99.09 750 99.21 99.12 99.02\n667 99.27 99.18 99.15 1000 99.28 99.20 99.11\n833 99.31 99.23 99.20 1500 99.37 99.30 99.21\n2000 99.43 99.36 99.28\n2500 99.47 99.41 99.33\n1 BIL means basic impulse insulation level.\nNote: All efficiency values are at 50 percent of nameplate rated load, determined according to the DOE Test Method for Measuring the Energy Consumption of Distribution Transformers under appendix A to this subpart K.\n(3) The efficiency of a medium-voltage dry-type distribution transformer manufactured on or after April 23, 2029, shall be no less than that required for their kVA and BIL rating in the following table. Medium-voltage dry-type distribution transformers with kVA ratings not appearing in the table shall have their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately above and below that kVA rating.\nTable 10 to Paragraph (c)(3)\nkVA Single-phase kVA Three-phase\nBIL 1 BIL\n20-45 kV 46-95 kV ≥96 kV 20-45 kV 46-95 kV ≥96 kV\nEfficiency (%) Efficiency (%) Efficiency (%) Efficiency (%) Efficiency (%) Efficiency (%)\n15 98.29 98.07 15 97.75 97.46\n25 98.50 98.31 30 98.11 97.87\n37.5 98.64 98.47 45 98.29 98.07\n50 98.74 98.58 75 98.50 98.32\n75 98.86 98.71 98.68 112.5 98.67 98.52\n100 98.94 98.80 98.77 150 98.79 98.66\n167 99.06 98.95 98.92 225 98.94 98.82 98.71\n250 99.16 99.06 99.02 300 99.04 98.93 98.82\n333 99.23 99.13 99.09 500 99.18 99.09 99.00\n500 99.30 99.21 99.18 750 99.29 99.21 99.12\n667 99.34 99.26 99.24 1000 99.35 99.28 99.20\n833 99.38 99.31 99.28 1500 99.43 99.37 99.29\n2000 99.49 99.42 99.35\n2500 99.52 99.47 99.40\n3750 99.50 99.44 99.40\n5000 99.48 99.43 99.39\n1 BIL means basic impulse insulation level/\nNote: All efficiency values are at 50 percent of nameplate rated load, determined according to the DOE Test Method for Measuring the Energy Consumption of Distribution Transformers under appendix A to this subpart K.\n(d) Mining Distribution Transformers. [Reserved]\n(e) Severability. The provisions of paragraphs (a) through (d) of this section are separate and severable from one another. Should a court of competent jurisdiction hold any provision(s) of this section to be stayed or invalid, such action shall not affect any other provision of this section.","path":["Title 10—Energy","CHAPTER II—DEPARTMENT OF ENERGY","SUBCHAPTER D—ENERGY CONSERVATION","PART 431—ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT","Subpart K—Distribution Transformers"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-10.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:24:09Z","sha256":"130cd841fdf6ad144be6b33ef988feff340cdd3f710fa291b2db30dfec855747","source_id":"us-cfr","stale":true,"prev":"us/10-cfr-431.193","next":"us/10-cfr-appendix-a-to-subpart-k-of-part-431"},"notice":"GroundRules: Original legal text. Not legal advice."}