Cable calcs using cable calc app
Working out cable size for a workshop.
100m long, 100a supply, mccb 100a zs- 0.23 ohms, in a duct on its own, tt earth on 300ma rcd.- 20 ohms
App says 50mm swa which I expect.
But if I alter earthing to tncs 0.35 ohms it says max ze exceeded zs of device.
Am I missing something here / Friday afternoon brain.
Thanks
Working out cable size for a workshop.
100m long, 100a supply, mccb 100a zs- 0.23 ohms, in a duct on its own, tt earth on 300ma rcd.- 20 ohms
App says 50mm swa which I expect.
But if I alter earthing to tncs 0.35 ohms it says max ze exceeded zs of device.
Am I missing something here / Friday afternoon brain.
Thanks