ahmetkazici
Electrical
- Apr 22, 2007
- 5
IEC 60364-5 Table A52-3 has a list of installation options for cable ampacities. It shows Items 70 through 73 as reference D ( underground in counduit, underground directly buried etc. )
Then I check PVC ( 70C )3 core cable ampacities, ( Table B52-4 Col7.)
It shows 122 Amps for 50 mm2 cable. ( NEC 310-16 1/0 gives 150 for directly buried at 75 C )
Then I check cable manufacturer's data sheets. The values are much much higher than IEC.
They list 188 Amps in ground ( Pyrsmian ) and 153 in air ( I really didn't understand how ground would have higher ampacity ). It also says "Current carrying capacities are valid at 20C earth temperature, 30C air temperature, 1 KM/W and 0,7 continous loading (cylic)"
Another problem with IEC's reading ( or my misunderstanding ) all underground insallations ( D installation ) give same ampacities ( eather directly buried, or in a conduit , or a cable duct underground ).
Any answers and ideas would be appreciated, and which value would be good to use ?
Then I check PVC ( 70C )3 core cable ampacities, ( Table B52-4 Col7.)
It shows 122 Amps for 50 mm2 cable. ( NEC 310-16 1/0 gives 150 for directly buried at 75 C )
Then I check cable manufacturer's data sheets. The values are much much higher than IEC.
They list 188 Amps in ground ( Pyrsmian ) and 153 in air ( I really didn't understand how ground would have higher ampacity ). It also says "Current carrying capacities are valid at 20C earth temperature, 30C air temperature, 1 KM/W and 0,7 continous loading (cylic)"
Another problem with IEC's reading ( or my misunderstanding ) all underground insallations ( D installation ) give same ampacities ( eather directly buried, or in a conduit , or a cable duct underground ).
Any answers and ideas would be appreciated, and which value would be good to use ?
