'v2
Sub DateFormatSelection()
    DateFormatRange Selection
End Sub

Sub DateFormatRange(rn As Range)
    On Error Resume Next
    Set rn = rn.SpecialCells(xlCellTypeConstants)
    On Error GoTo 0
    If Not rn Is Nothing Then
        Application.EnableEvents = False
        Dim Application_Calculation As Long
        Application_Calculation = Application.Calculation
        Application.Calculation = xlCalculationManual
        Dim cl As Range
        Dim txt As String
        Dim vl As Double
        For Each cl In rn
            txt = cl.Value
            If Len(txt) > 5 Then
                vl = Val(Left(txt, Len(txt) - 5)) / 24
                vl = vl + Val(Left(Right(txt, 5), 2)) / 24 / 60
                vl = vl + Val(Right(txt, 2)) / 24 / 60 / 60
                
                cl.NumberFormat = "[h]:mm:ss;@"
                cl.Value = vl
            End If
        Next
        
        Application.EnableEvents = True
        Application.Calculation = Application_Calculation
    End If
    
End Sub