Sum up the time format

Anonymous,

I was not able to reproduce your issue where you were unable to use your measure in the Value Field.

Please review what I did do to see if this is a possible solution for you.

Edit - added new picture: The above screen capture shows the final Custom Column Added in the Query Editor, below is the Query Settings for the Add Column Custom Column 'Time Spent' that produces the above image. 

Edit - Close & Apply returns you to Power BI where I added a different Time Format to 'Time Spent' to more align with what you had in your original post. See below.

Now you can do a SUM( ) measure of 'Time Spent' which I called Duration, also show below.

The Measure First New Duration was what I achieved with your code. However, I could not get what I believed you desired.

New Duration = 
VAR TotalSeconds=SUMX(Table2,HOUR(Table2[Time Spent])*3600+MINUTE(Table2[Time Spent])*60+SECOND(Table2[Time Spent]))
VAR Days = TRUNC(TotalSeconds/3600/24)
VAR Hors = TRUNC((TotalSeconds-Days*3600*24)/3600)
VAR Mins = TRUNC(MOD(TotalSeconds,3600)/60)
VAR Secs = MOD(TotalSeconds,60)
return IF(DAYS=0,"",IF(DAYS>1,DAYS&"days",Days&"day"))&IF(Hors<10,"0"&Hors,Hors)&":"&IF(Mins<10,"0"&Mins,Mins)&":"&IF(Secs<10,"0"&Secs,Secs)

Result Visuals:

 Oh, I wasn't able to create a leading zero on the hour, but I was testing what adding 12 hours to John on Day 1 and what the display would look like.