Lead Sheathed Cables/Current Ratings/Rating Factors for Thermal Resistivity of Soil


RATING FACTORS FOR VARIATION IN THERMAL RESISTIVITY OF SOIL
TWIN OR MULTI-CORE CABLES LAID DIRECT IN THE GROUND
Nominal Area of Conductor Sqmm Thermal Resistivity of Soil in °C m/w
0.7 0.8 0.9 1.0 1.2 1.5 2.0 2.5 3.0 3.5 4.0
1.5/2.5 1.12 1.09 1.07 1.04 1.0 0.94 0.86 0.80 0.75 0.70 0.66
4 1.13 1.10 1.07 1.05 1.0 0.94 0.85 0.79 0.74 0.69 0.65
6 1.14 1.10 1.07 1.05 1.0 0.93 0.85 0.79 0.74 0.68 0.64
 
10 1.15 1.11 1.08 1.05 1.0 0.93 0.85 0.78 0.73 0.67 0.63
16 1.16 1.12 1.08 1.05 1.0 0.93 0.84 0.77 0.72 0.66 0.62
25 1.17 1.13 1.09 1.05 1.0 0.93 0.83 0.77 0.71 0.65 0.61
 
35 1.17 1.13 1.09 1.06 1.0 0.92 0.83 0.76 0.71 0.65 0.61
50 1.17 1.13 1.09 1.06 1.0 0.92 0.83 0.76 0.71 0.65 0.61
70 1.18 1.14 1.09 1.06 1.0 0.92 0.83 0.75 0.70 0.64 0.60
 
95 1.18 1.14 1.09 1.06 1.0 0.92 0.83 0.75 0.70 0.64 0.60
120 1.19 1.14 1.10 1.06 1.0 0.92 0.82 0.75 0.69 0.63 0.60
150 1.19 1.14 1.10 1.06 1.0 0.92 0.82 0.75 0.69 0.63 0.59
 
185 1.19 1.14 1.10 1.06 1.0 0.92 0.82 0.74 0.69 0.63 0.59
240 1.20 1.15 1.10 1.07 1.0 0.92 0.81 0.74 0.69 0.63 0.59
300/400 1.20 1.15 1.10 1.07 1.0 0.92 0.81 0.74 0.69 0.63 0.59