VBA code to copy and insert data changing date value

I have an excel template that captures network outages incidences, calculates the minutes of outage by checking the diff between incidence start time and incidence end time and based on this calculates network availability (RNA). I want to apportion the minutes of outage and hence the RNA appropriately.My problem is I need a macro that checks whenever an incidence end time crosses over midnight, it should calculate the minutes for that day,copy the incidence details and insert them into a new row below, change the incidence start time to next day and calculate the minutes for the following day.
Note, some incidences are open for long, so the number of times the macro copies and inserts data is a variable.