Formula to add rows based on required capacity

Thanks for the reply, its not exactly what I need, but I may be able to modify that.

I've attached another sheet, showing two cabinets (on CAB1 + CAB2), what I need to be able to do is if for example I now need more ways on CAB2, to select the drop down to say 10 ways and I add the blank (formatted) rows for me to populate.