Best Bit + Technique for Running New Eletrical Behind Drywall

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Forum topic by wilschroter posted 02-14-2019 11:36 AM 555 views 0 times favorited 8 replies Add to Favorites Watch
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56 posts in 913 days

02-14-2019 11:36 AM

I’ve seen some installers in my house (running cabling) use long bits through studs in my house without having to rip up the entire drywall area. I love this idea but can only picture myself firing that long bit right through the other side of the drywall!!

I’m wondering if any of you folks here have experience using these long bits and what the technique is for keeping the bit “straight” through potentially a few studs. Also, roughly how far can you go with a bit (2, 3 studs?) before it’s just not feasible anymore?

8 replies so far

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John Smith

1828 posts in 551 days

#1 posted 02-14-2019 11:51 AM

this is an opportunity to hone your drywalling skills !!
what do you want to do exactly ? [a drawing or sketch will help a lot].
when going through 2 or 3 studs, and you want to “keep it straight”,
drilling the hole is only part of the project. fishing the wire from one
point to the other is the stumbling block for most without the proper tools.
so cutting out the drywall is the fastest and safest way for the novice in order
not to compromise existing things such as hidden wires or plumbing that may
not appear with using the common stud finder tools.

LumberJocks has a sister site called DIY Home Projects
where this subject is discussed regularly and answered by the pros.
stop by and check it out when you have time.



-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

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John Smith

1828 posts in 551 days

#2 posted 02-14-2019 02:14 PM

assuming that your wall studs are 16” on center, I put four
2×4” pieces 16” OC and with a dowel in a drill, you can see
that you “might” be able to go through one stud – giving you
room to go about 30 inches from an existing outlet for another one.
any further than that, your concerns are confirmed that you will
more than likely come out the other side of the wall.
thus – cutting out, replacing and finishing drywall is the next option.
and if there is any insulation in the wall, plan on additional frustrations.
have fun !!


-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

View smitdog's profile


430 posts in 2493 days

#3 posted 02-14-2019 02:43 PM

If you have enough holes to drill then it may be worth getting something like this Eagle Tool flex auger bit from Amazon. It is 72 in. long and flexes so you can get into the wall cavity and drill along the wall instead of at an angle which will cause trouble like John’s illustration above.

-- Jarrett - Mount Vernon, Ohio

View bmerrill's profile


50 posts in 461 days

#4 posted 02-14-2019 03:10 PM

It is important to drill in the center of the stud and with a hole no larger than 3/4” diameter so nails/screws are not driven in the wires. A 3/4” hole is adequate for 3-#12/2 Romex cables. Because you have no idea of what other wires or plumbing maybe in the walls, its best to open the wall up if you are drilling through more than 2 studs. If the drywall will be finished with paint or paper or more than 3 cables are needed, requiring 2 holes, I prefer to cut a wide section out 8-12” as it is easier to finish and is stronger. If the finish is tile, wood planks, etc., then a narrow width 3-4” works fine, but still apply 2 coats of mud to seal the wall.

-- "Do. Or do not. There is no try". Yoda

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1036 posts in 294 days

#5 posted 02-14-2019 05:39 PM

I got a kit like this at home depot
With the guide I am able to go through 2 studs no problem. I did go through 3 in order to do some wall sconces, but it took quite some time, and I had the bigger round cutouts for the boxes that helped. The problem is that the arc it creates once past the 2nd stud wants to continue outwards. In my case it was hitting the outer OSB and I was able to kind of “bounce” off it. Normally I would pull through the attic and down,(or crawl space if the house had it), but in my instance it was the lower part of a 2 story with vaulted ceilings. I don’t really use the finger-trap to pull the wire through though, I usually strip a strand of wire, and put it through the hole in the end of the bit, bend it back and twist multiple times and wrap with tape.

View F250's profile


32 posts in 141 days

#6 posted 02-14-2019 06:58 PM

I use an 18” stainless mud pan and a 14” stainless drywall blade to finish the patches I make when running new cable in existing walls. I’ve played with the flex shaft bits, and I’d rather keep it simple with old school techniques.

My holes in the drywall go completely from one stud to another, or across 2 or three studs if necessary. I also use two such holes in a vertical routing (one above and one below each fire block). The holes I make are approximately 8-10 ” high and whatever width I need, but the width always ends at a stud face. To patch, I quickly scab in two 8” pieces of 2x material on the inner face of each openings so the sheet rock patch ends have something to be screwed to. Fiberglass mesh tape and simple pre-mixed mud become friends with my pan and blade, and everything finishes very nicely after several coats of skim with minimal sanding.

I end up with a large flat patch which is completely undetectable and does not crack around the edges. Until the patches are installed, I have ample room to use my drill/drivers and hands and screwdrivers and pliers to bore holes, pull wire, make splices, install junction boxes in the wall, or whatever else is necessary. Each of these patches helps me refine my mud-skimming and finishing skills, so I am better equipped to do the next drywall task with more proficiency than before.

Does that mean that I’m one of those Luddites I keep hearing about?

-- Pete -- Bark less, Wag more, and SHOW COMPASSION to everyone you meet.

View Mainboom's profile


90 posts in 145 days

#7 posted 02-14-2019 11:38 PM

typically its 2 studs.. and lots of practice. also the drill used in not a normal drill its typically a right angle mud mixing type drill

-- CRANE OPERATORS START EARLY because iron workers need their heros ready when they wake up

View Mike_D_S's profile


595 posts in 2603 days

#8 posted 02-15-2019 02:05 AM

Even though I did my own repipe and drywall work, when I got the initial quotes on getting a PEX repipe, they quoted out the drywall repair cost for getting the guy to come out and fix all the little holes from the repipe.

I think if you google repipe plumbers you could probably get a reference for a a drywall guy who would patch some holes for not too much cash.

When you drill make sure you know what is on those studs. Drilling through some romex stapled to the side of a stud will ruin your day. Look for outlets, switches, etc on the front and back of the wall. Also think about plumbing and gas runs. Hopefully you’ll have an idea, but my house is a Pulte and was wired by a drunk monkey who was apparently paid not by the hour, but by the number of direction changes the wiring makes.

-- No honey, that's not new, I've had that forever......

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