In a plant, cable installation methods and arrangement is one of factors to decide cable ampacity derating factor. IEC standards 60364-5-52 has listed in detail 73 methods totally. However, for the cable derating purpose, there are 10 designation of methods recommends in table B.52.1. These methods together with ambient condition and installation grouping will come out cable current carrying capacities.

What is the Reference Method C?
With reference to above descriptive table, installation method C refers to cable mounting on a wooden wall so that the gap between the cable and the surface is less than 0.3 times the cable diameter. The term ‘masonry’ can be brickwork, concrete, plaster and similar (but excluding thermally insulating materials).