My house was built in the before outlets were grounded and most of the house has old receptacles. I'm under the impression (from an electrician I had out to do a job that was over my head) that I can simply change the receptacles and run a ground wire down into the existing box. As part of the job I had the electrician out before, he grounded all the outlets in my kitchen this way. He had mentioned that there was a grounding block in the attic and said I only had to run the ground wire to that box, saving myself the hassle of trying to run everything into the box outside. Can someone confirm this for me? Also, and this may be a dumb question, but could I theoretically ground all the outlets in each room, connect them all to a single ground wire, and run one wire from each room to the grounding block? I don't know a ton about electrical, so I don't know if this is a dumb question or not. Let me know if this doesn't make sense and I need to clarify what I'm asking.