How to avoid cutting electrical wires when cutting into drywal

Question

I want to install an attic access pull down ladder in the ceiling of my garage to put plywood on the rafters for storage. How do I know where to cut into the drywall of the ceiling without cutting wiring?

Answer 1

First you need to lay out the general area where you want the opening. It needs to fit between 24" centered ceiling joists.

Properly installed electric cabling is always at least 1 1/2" away from the back edge of the sheetrock (or protected by a metal shield). So, if you cut a small hole near the middle of your proposed opening with a shallow cutting tool, such as a utility knife or a multisaw, big enough to get your hand and arm through, you can reach in to make sure there are no wires draped in the area where you are working. If clear, cut a bigger hole with a drywall saw or multitool, large enough to get your head through. Insert a light and then your head and scan the area.

Now you're prepared to cut the full opening back to the joist with no surprises.

Answer 2

@bib: I cant say I have seen metal around long runs of power cable in joists... ever. But it is certainly true it should never be within nailing areas. I.e., 1-1/2". I think most electricians aim for at least center. (so on a 2x6, it would be 2-3/4 or so off.

My approach would be: @Tyson has a point, it is best to visually look first. So if you have an access area, go inspect from above. Start your hole from above. Use a nail, screwdriver, a drill, whatever.

Then you can use a drywall saw or the like, and knowing there is no wire to hit, go to town. Preferably with a drywall saw as you aren't going to do much damage to the joist with it.

Cut to the joist in each direction, enough off center to work it from both sides. Then as @bib was getting at, score the bottom area with a knife to cut through the paint. Score an entire box the shape you want keeping it inside the edge of the joist. Cut both ends perpendicular to the joists and then down the middle. You should now be able to press up and get a clean break, score the other piece from the top, and do the same. Both pieces should come out without damaging the painted surface.

Answer 3

If you are certain of the location, just use a regular hammer, 14oz or 16oz or ..., to knock a small hole in the ceiling sheetrock, then rip off by pulling down enough sheetrock to stick your head up there and look for electrical wiring, then enough for your shoulders to look into other bays.

You can't count on the ceiling being framed strong enough to serve as storage.

Nowadays, inspection cameras for wall/floor cavities etc are cheap. see amazon.com for borescopes or endoscopes that plug into smartphone or laptop. There as little as $5 plus shipping online.