A couple years ago I decided to add a light in my bedroom. I drilled 3/4 inch holes about 4 inches from the bottom in about half of the 2x12 floor/ceiling beams and about 4 feet from the wall so I could run the wire. The beams span about 15 feet over my bedroom and the area I drilled into equals about six feet or so, basically to the middle of the room. At the time I was not even the least bit concerned about it, but now the people that recently moved in above me have kids or something because it seems like they run and jump a lot. Anyway, I am beginning to question the decision. Is it something I should be concerned about?

 

Your 3/4" holes are OK. Off the top of my head I think the maximum size hole allowed in a 2X8 joist is around 2 1/4" located in the middle third of the joist.

 

You are fine with the holes.

If you notice ceiling movements or vibration because of the tenants activity above then the problem lies in how the framing was sized/spaced/specified or installed or both in the first place.