In Prepositions^x, Present perfect^x, Clauses^x

Earlier today, I had posted a message concerning the very same issue. I had not been fortunate to have found this message thread beforehand. (Uh oh, here I am getting tangled up in verb tenses with the preceding sentence. I mixed pluperfect with present perfect. Groan.) So, are you saying that...

Additionally: 1) Can we rely on his installing all our equipment correctly? ] This is fine; but many native speakers would say "...on him installing all our..." 2) I object to his installing our equipment. ] Again, fine; but many native speakers would say "...to him installing..." 3) The...

Yes, those sentences are correct. You said though, that "'since' is usually used with a main clause in present perfect tense". I don't think that's true. "Since" is simply a preposition which means "the period of time STARTING at the described moment". Similarly, "until" is a preposition which...