Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus
We are trying to calculate the heat disipated via the cable under varying conditions, so wee need to us Watts/m as a measure, and if you want to "FORGETN THE SOODING TABLES" you need IEC 60287.
You need to consider many factor's, from the construction of the cable, to the A/C resistance taking into account the Skin effect and the Proximety effect, then you need to consider the external influences, then as i have said after 4 pages of equations you can calculate the Heat disipation of the cable, the tables etc in BS 7671 are not far off the calculted.
I don't believe at any point we were trying to calculate watts/meter. We were taking those as a given (H).
We are trying to calculate the heat disipated via the cable under varying conditions, so wee need to us Watts/m as a measure, and if you want to "FORGETN THE SOODING TABLES" you need IEC 60287.
You need to consider many factor's, from the construction of the cable, to the A/C resistance taking into account the Skin effect and the Proximety effect, then you need to consider the external influences, then as i have said after 4 pages of equations you can calculate the Heat disipation of the cable, the tables etc in BS 7671 are not far off the calculted.