![]() ![]() Note: The current carrying capacity for cables laid in direct contact with soil having a thermal resistivity of 2.5K.m/W and at a depth of 0.7m is approximately 10% higher than the values tabulated for Reference Method D. If the specific installation parameters are known (thermal resistance of the ground, ground ambient temperature, cable depth), reference can be made to the cable manufacturer or the ERA 69-30 series of publications, which may result in a smaller cable size being selected. The values given for this method are those stated in Appendix 4 of BS 7671 and are based on conservative installation parameters. Twin And Earth Table 7671 Full Duration Of This will usually become the case for installation in domestic or equivalent premises. The cable is drawn into a 100mm diameter plastic, earthenware or metallic duct laid in direct contact with soil having thermal resistivity of 2.5K.m/W and at a depth of 0.7m. For example - Installation method 70 of Table 4A2 (multicore armoured cable in conduit or in cable ducting in the ground). ![]()
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