I've found the 'where' to drill a hole in the joist span to run wire across ceiling cavity (multi-story on first floor so no attic access). What I can't find is how does someone drilling from an access hole in the ceiling into a floor joist know that there isn't anything on the other side of the joist (e.g. stapled ROMEX on joist, etc.)? Example, if I have an access hole in my kitchen ceiling between joists 2 and 3 and want to drill through joist 2 to get to joist cavity 1 and 2, and I don't know if there's a previous remodel or wire-run stapled onto the non-viewable side of joist 2, how can I be sure nothing is there (is there a code or standard?…of course, you never really know without laying eyes on it and opening up the joist 1 & 2 cavity) but obviously would like to avoid additional work of opening a new cavity just to inspect).
What protects an installer from drilling a hole in joist and not hit anything
constructiondiy-vs-proinstallationremodeling
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Best Answer
If it is at all possible, you make sure you can see the other side before you drill. In some areas fishing wires into an unopened space is considered concealed work and must be done by a master electrician.
That said, a few tricks I've seen used:
There are many types of electrical toner. I don't know the name of the one you want for this, we just called it an in slab or in wall toner, but it looks like a metal detector and you can sense wires 6 or 8 inches deep in something.
For holes into the top of walls where something may be stapled to the underside of the stud, you can use a hole saw without a pilot bit (only pilot to get started) and drill only part way through then smash out the plug.
You can also use a skinny volt ticker like the Fluke LVD1A taped to a stick to sense the bottom of a smaller hole before you drill through.
Depending on the geometry of where you want to check, a stud sensor with electrical sense has better depth than a volt ticker at low price.
You can get a cheap usb inspection camera for your laptop or phone and attach it to a wire to make a camera on a stick. Drill a hole somewhere safer, put the camera in, take a look.