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Quick selection: copper thickness by soil corrosivity
Copper-clad steel selection guide, part 5 of 8
China's two anti-corrosion earthing codes (DL/T 2094-2020, Q/GDW 12015-2020) give a quick-selection rule, which DL/T 2650-2023 Table 4 makes a normative minimum copper thickness at any measuring point:
≥ 0.25 mmLow-corrosion soil. Electroplated or continuous-cast.
≥ 0.6 mmMedium-corrosion soil. Normally continuous-cast (plating does not reach it).
≥ 0.8 mmHigh-corrosion soil. Normally continuous-cast; 1.0 mm for longer design life or harsher duty.
- The copper thickness for each soil class (low 0.25 / medium 0.6 / high 0.8 mm) is set by the two anti-corrosion standards Q/GDW 12015-2020 and DL/T 2094-2020, and adopted in DL/T 2650-2023 Table 4; the corrosion allowance is calculated per DL/T 2094 (DL/T 2650 cl. 5.1.1.3). Soil of pH < 4.5 is designed one corrosivity class higher (DL/T 1312-2023 cl. 4.6).
- DL/T 2650-2023 selection: hot-dip galvanised steel for low corrosivity, copper-clad steel (or galvanised steel with cathodic protection) for medium, copper or copper-clad steel for high; indoor and underground substations shall use copper (cl. 5.1.1.5, 5.1.1.7). Extremely corrosive soil calls for copper (DL/T 1312-2023 cl. 4.6); we will say so when it applies.
- Where the calculated copper thickness exceeds 1.0 mm, DL/T 2727-2023 asks for a techno-economic comparison with solid copper before deciding.
Quick selection is for the case of "no soil data yet, quotation needed now". With a design life and soil data, use the precise method below.
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