I normally use ELEK Cable Pro to calculate my cable sizes and it works very well however I have a project at the moment which has a circuit which I need help calculating the correct size cable for; The circuit is for an 18.5kw 400v motor. I have used the following Load – 18.5kw V- 400v Efficiency – 90% PF – 0.95 Voltage Drop – 5% Cable Length – 50mtr Earthing – TN-C-S Correction factor – 0.9 Protective device type B 40A Installation – In cable duct Cable Type – 4 core armoured XLPE My problem is that the software gives the option of 5 different circuit arrangements 1. Radial 2. Sub Mains 3. Ring 4. Motor DOL 5. Motor Star-Delta My motor is using a variable speed drive, which isn’t an option. If I use the software and select DOL then it tells me 16mm cable but any of the other options gives me 10mm. In my experience I would think 6mm would be ok if the MCB had been a Type C 32A but I didn’t supply the panel and it is a 40A B type which I am stuck with. Can anyone advise? I would think if I select Motor star-delta in the software and use a 10mm cable then my cable report would be okay and I would be covered?