Drilling concrete for anchors ?

You cold take a steel rod or punch and place it in the hole and hammer on it to see if that breaks up the rock or if it is in fact rebar. I do not understand how you are using a hammer drill in a place that you can't get your head above the hole though. If in fact you are using a concrete bit which does not look like a regular drill bit, masonry bits have little wings on the tip, and will not even come close to drilling steel.