With reference to 433.1.204 and cable as installed has min capacity of 20A if protected by a 30A or 32A. If the protective device is reduced to 20A how is the new minimum as installed capacity calculated or arrived at ? I've been looking in the Electrical Installation Design Guide, but the answer is avoiding my eyes.
2.5mm2 cable installed to 101 giving an as installed current carrying capacity of 17A. Granted not much point in this installation choice and 4mm2 should have been used, but back to my question. How do you evaluate the minimum required current capacity of a cable installed as ring protected by a device.20A device. As the cable is installed it is 3 amps short, but there is a significant drop from 32A to 20A so I do not suppose there is a problem, but I was looking for a definitive answer other than volt drop which would still need an idea max current.
2.5mm2 cable installed to 101 giving an as installed current carrying capacity of 17A. Granted not much point in this installation choice and 4mm2 should have been used, but back to my question. How do you evaluate the minimum required current capacity of a cable installed as ring protected by a device.20A device. As the cable is installed it is 3 amps short, but there is a significant drop from 32A to 20A so I do not suppose there is a problem, but I was looking for a definitive answer other than volt drop which would still need an idea max current.
