Cutting concrete for electrical for Island

Our friends had a contractor rent a gas powered saw to cut their concrete...our Cabinet maker used this $20.00 Harbor freight angle grinder with steel saw blade....it took only 15 min to do now we start chipping out...next week pantry goes in then the rest soon after..
in the pictures show the wall with plastic that kept the dust localized we used Fast caps 3rd hands to hold up plastic ..then the marks to cut ..then the cut....