CURRENT RATING FACTORS FOR PVC

Normal Installation Conditions
  • Ground temp. – 30°
  • Ground temp. – 30°
  • Max. operating conductor temp 70°
  • Soil Thermal resistivity 150 °C c cm/w
  • Depth laying 75 cm
  • Short circuit rating 160°C
RATING FACTOR FOR VARIATION IN AMBIENT AIR TEMP
Air Temperature °C 15 20 25 30 35 40 45 50 55
Rating Factor Fo r( PVC) 1.40 1.32 1.25 1.16 1.09 1.00 0.90 0.80 0.69
For HR PVC 1.28 1.22 1.17 1.12 1.06 1.00 0.94 0.8 0.82
RATING FACTOR FOR VARIATION IN GROUND TEMP
Ground Temp °C 15 20 25 30 35 40 45 50 55
Rating Factor For ( PVC) 1.17 1.12 1.06 1.00 0.94 087 0.79 0.70 0.60
For HR PVC 1.30 1.09 1.04 1.00 0.95 0.90 0.85 0.80 69
RATING FACTOR FOR DEPTH OF LAYING
Depth of laying (cm) 75 90 105 120 150 180 270 360 450 545
Rating factor for (PVC) 1.00 0.99 0.98 0.97 0.96 0.95 0.92 0.91 0.90 0.89
GROUP RATING FACTORS FOR TWIN AND MULTICORE CABLES DIRECTLY LAID IN GROUND IN HORIZONTAL FORMATION
No. of Cables Touching 15cm 30cm 45cm 60cm
2Cable 0.78 0.81 0.85 0.88 0.90
3Cable 0.68 0.71 0.71 0.81 0.83
4Cable 0.61 0.65 0.72 0.76 0.79
6Cable 0.53 0.58 0.66 0.71 0.76
8Cable 0.48 0.54 0.62 0.67 0.72
GROUP RATING FACTORS FOR TWIN AMD MULTI CORE CABLES DIRECTLY LAID IN GROUND IN TIRE FORMATION
No. of Cables Touching 15cm 30cm 45cm 60cm
2Cable 0.80 0.84 0.87 0.90 0.91
4Cable 0.60 0.66 0.73 0.77 0.79
6Cable 0.51 0.57 0.63 0.67 0.69
8Cable 0.46 0.51 0.56 0.60 0.61
RATING FACTORS FOR MULTICORE CABLES LAID ON RACKS IN AIR (WITH CABLES TOUCHING)
No. of Racks Number of Cables per rack
1 2 3 6 9
1 1.0 0.84 0.80 0.75 0.73
2 1.0 0.80 0.76 0.71 0.69
3 1.0 0.78 0.74 0.70 0.68
4 1.0 0.76 0.72 0.68 0.66