need help with duration (cumulative time) calculation

Hello;
I'm trying to come up with an elegant way to calculate time duration as a sum of cells which contain either m:ss, or mm:ss, or h:mm:ss, or, finally, hh:mm:ss (these are individual durations, which I want to add, to obtain the total time)

An excerpt from the data set:
0:11 (0 min 11 s)
14:42 (14 min, 42 s)
24:08:00
0:04
2:36
0:40

I've get the data by cutting and pasting from an html report.
If I change the column display format to General, the above numbers change to decimal (I know this is how excel is keeping time internally), but I think Excel messes the things up, considering for instance 0:11, as 0:11:00. I believe it does that, because if I change the display format into Time, that's what it does to all values.

I started creating an arcane formula, evaluating string lengths and using left, right and mid to extract the values for each column, but it is quite strange to have to do that. It also doesn't work, because Excel doesn't allow me to operate on the cell as a string of characters. It does its own thing, and the string operators don't make sense... Unless I convert that column into text (outside excel - in notepad - and re-paste it in, formatting the column as Text). After that string operators work, but I won't call this a solution ...

Any suggestions?
Thanks much,
HG

For the durations where Excel considers seconds to be minutes, etc, have you considered dividing by 60?

If you are pasting your examples into Excel, they will most likely be interpreted as time values. To resolve this, simply divide the pasted values by 60 to convert hours to minutes and minutes to seconds.

For example, Excel will, by default, interpret "2:36" as 2 hours and 36 minutes. Divide this pasted value by 60 to get 2 minutes and 36 seconds.