Bit of an old post... but having been torqued off a ladder and hanging 6' in the air by a corded drill and nailbiter bit once or twice, there are some things I do to keep it from happening again:
~ use something like this:
http://www.toolup.com/Milwaukee-48-...ZGWesnbbs-sTlyOqSV3YhRmJSN3fSnipjAaApYd8P8HAQ
to drill from the ground and not a ladder
~ use the smallest bit possible (size and length).
~ cordless drills dont have the torque of corded ones, tho are better in small installs than lugging around a larger drill and cord. If they hang they generally are an inconvenience rather than an injury
~ use sharp bits and keep them perfectly perpendicular to the hole you are drilling.
~ If you're drilling thru more than one framing member, it helps with some bits to pull the drill out to clear debris.
~ this one is obvious, but wear safety glasses/dont look up when drilling overhead, lest you want a face full of sawdust/chips.
~ generally, there are less nails in top plates a bit away from a stud.
~ if nails arent a concern, tri-flute bits will drill quickly and leave clean holes. Splintering a stud with a crap drill bit then having the splinters get in the way of pulling wire/cable is a big pet peeve of mine.
Not a personal safety issue, but always check the other side of what you're drilling, just in case there is a FA pull box conduit inline with your drill path, or something. :roll:
A super hole hawg or equivalent is the best for heavy drilling thru wood. I dont think Ive ever seen a commercial plumber w/o one.
concrete drilling is much the same as above with special attention to keeping the drill level/plumb, and clearing debris. and if it jams, check to see if you hit rebar or broke loose a piece of aggragate in the hole.