Drilled into studs, light flickered momentarily but everything else seems fine now - should I be worried?

Question

I was installing shelving in my closets, when drilled a hole into studs, the lights flickered momentarily for 2 seconds.

I stopped drilling, and everything else seems fine now. The circuit didn't break and the lights are no longer flickering.

There doesn't seem to be any sockets around the switch.

Should I call an electrician or is there anything I should test?

When was your house built? Do you know if you have AFCI breakers? Was your drill plugged it, or is it cordless? — Edwin, Aug 22 '16 at 03:18
Sounds like an excellent excuse to buy one of those hand-held inspection cameras on a gooseneck, with a small LCD screen. That's instead of tearing open the wall lining. — Criggie, Aug 22 '16 at 20:02
Getting over the fear of patching drywall is a needful thing, the way houses are built. I'd put access panels all over the place, personally, but it's true that cutting a hole and patching it is not that big of a job, really. Just cut a hole in a closet myself to install bracing to support a TV mount - sure, i could have done some clunky thing on the face of the wall, but it would have been clunky, while this will be invisible when the closet wall is patched. I'm happy to report that the wiring in that case is right where it should be, in the center of the stud. Camera >> drywall patch cost. — Ecnerwal, Aug 22 '16 at 21:12
@Ecnerwal There are cheap cameras that use your phone as the screen that when you factor the time/hassle of opening and patching a wall are going to be more economical. Of course if you have spare sheetrock, join compound, tape, etc then patching walls feels free. — Dean MacGregor, Aug 23 '16 at 14:57
@Criggie I second your suggestion, once you have one of those you'll wonder how you did without it. They are amazingly useful. — barbecue, Aug 24 '16 at 00:43
Before you start cutting holes in walls I'd inspect the drill bit. If you did short wires there may be an evident burn on the bit. You may also have heard a pop. If either is true, then you definitely hit wiring and need to switch off the circuit at the breaker panel straight away. — cloudworks, Aug 24 '16 at 06:20

score 56 · Answer 1 · answered Aug 22 '16 at 03:40

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So you stopped drilling and it got better. Of course, if you put in a screw it might get worse in a hurry.

Best bet is that you nicked the insulation on a wire or wires - either from drilling too deep, determinedly drilling though something that was supposed to prevent you (or warn you by being difficult to drill, compared to wood anyway) from drilling into it, or because it was installed improperly (too close to the surface, without steel protector plates.)

As such it would be a very good idea to turn off the breaker for the affected circuit, open up the wall, have a look, and call an electrician if you are not comfortable fixing electrical things yourself.

answered Aug 22 '16 at 03:40

Ecnerwal

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This. Make sure you have verified whether there is any damage. Not verifying now could lead to hazards in the future. – Mast Aug 22 '16 at 10:35
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Your first paragraph is priceless. And I agree with the rest of what you wrote as well. – End Anti-Semitic Hate Aug 22 '16 at 11:56
If you have confirmed that your drill isn't causing the problem, then it's definitely this. You need this fixed before a bug crawls in, shorts the circuit, and starts a fire. – Nelson Aug 23 '16 at 07:55
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@BobJarvis - I prefer to respect electricity through understanding rather than fear it through ignorance. – Ecnerwal Aug 23 '16 at 13:40
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Couldn't he just use a multitester with a voltage detector? They're like $20. If that doesn't go off no point in tearing the wall open...and now you've got a multitester to start you on the way to learning about how electricity works. – Raydot Aug 24 '16 at 21:32

score 12 · Answer 2 · edited Aug 23 '16 at 13:30

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There are three options, some already mentioned.

You were drawing too much power the power line could provide.
You can try it by drilling into similar material and watch the lights. If it will flicker you should turn off another device (washer, fridge,...) for a while. If not I have bad news for you...
You were drilling into powerline.
Turn off main breaker, insert metal rod in the hole and find what line is connected to it. Open the wall and find the wires near the hole. Or, which is much cleaner way, call electrician. They can detect wires without opening the walls, they use metal detectors for it.
If all above is false, then you had a bad luck and maybe you and your neighbours were drawing too much at the moment, there was temporal power shortage in your area, who knows. (Thanks Steve Jessop for comment)

edited Aug 23 '16 at 13:30

user6297

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answered Aug 22 '16 at 10:29

Crowley

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Hate to say it but if you're listing all options then it's also possible that it was a complete co-incidence, and the house power supply dropped while the questioner happened to be drilling. Obviously that's unlikely enough that you don't want to put a screw into the drilled hole and lick it. But if thorough investigation shows that the drill is fine on the house electrics, and there's no wire in the wall anywhere near the hole, you have to put it down to bad luck. – Steve Jessop Aug 22 '16 at 15:57
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Bad luck is the best option but worst to prove. – Crowley Aug 22 '16 at 16:00
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Vibration is another option: the drilling caused a poor connection somewhere nearby to shift. – RoadieRich Aug 22 '16 at 19:34
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"put a screw into the drilled hole and lick it" -- Steve Jessop. – MikeP Aug 23 '16 at 00:45
@MikeP For that way of testing I'd use 3 students of physics or at least 10 people. All holding hands forming a chain. One end holds the ground, other end touch the screw. For 10 people everyone get chosked by 23 VAC, which is quite safe... – Crowley Aug 23 '16 at 09:27
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I second @RoadieRich that a fourth possibility is the vibration from the drilling causing the lights to flicker, either because it rattled the light and/or its housing, or because there's another loose wire feeding the light that passes near a structural member connected and/or close to the drilling site.
Vis-a-vis your first possibility, when you "try ... drilling into similar material" it should be using the same power setup - the same extension cord plugged into the same outlet, etc.

user6297

Aug 23 '16 at 13:32

@user6297 this is the option "Bad luck - who knows"... Thanks for edit. – Crowley Aug 23 '16 at 13:36

@ Crowley - No, I don't think it's "bad luck" that @RoadieRich and I are talking about, because it should be reproducible, so long as the light / housing / wiring remains loose. – user6297 Aug 24 '16 at 17:25

JimmyJames · Answer 3 · 2016-08-22T17:24:15.370

Since this is closet, there seems to be no real reason not to go ahead and remove the wallboard (or plaster and lath) a few inches to each side of the stud and see if there is a wire there. You should probably get a non-contact voltage detector and check the vicinity of where you are going to cut just in case there is wiring just behind the wall. Nothing particularly special about this model. There are other similar devices from other makers and you can get them at your local big-box store. Note that just if it doesn't detect anything, that doesn't mean you haven't hit a wire. It might just be too far in the wall.

If there is a wire where you drilled, you should assume you've hit it and repair the wiring. If you decide to fix it yourself, make sure match the wire gauges and put any splices in a junction box that is accessible.

Repairing the wall is fairly easy if you don't have to worry about making it look nice and generally that's not a concern inside a closet. Just cut a piece of drywall a little larger than the hole you created, put it over the hole, trace around it and cut the hole to fit the piece, screw the piece to the stud (short screws!) apply a little mesh tape and smooth on some joint compound.

I hope the asker does this first. Those voltage detectors can be had for under $10 sometimes and will give a quick confirmation whether or not there are any live wires in the wall. I'm assuming from the question that the drill didn't go into studs, but was aiming for and missed studs. If the drill did in fact go through a stud, the chance to hit a wire is slimmer. I'd prefer verifying there's live wire near the hole I drilled before I started ripping open the wall. — Stefan Mohr, Aug 23 '16 at 20:46

score 4 · Answer 4 · edited Aug 24 '16 at 11:10

So you now have an electrified shelf that alerts you when your kids try to get to their Christmas presents before Santa delivers them. What's so bad? :)

Craftsman Wall Scanner with AC Wire Warning

Something like the above (a stud finder/scanner) will tell you if an electrical line is at the spot you drilled. If there is one then you will have to open the wall to determine if you killed the Romex.

If you look at the light switch box you can tell of they used conduit (required for many cities). If there is conduit run for the light switch, then conduit was run for the wire to the light and you probably did not drill through wiring.

score 3 · Answer 5 · answered Aug 22 '16 at 17:52

If you don't want to start taking walls down (it can be a very time consuming job, especially the clean-up afterwards) to have a look, I would suggest calling an electrician in and asking them to run an insulation safety check. They have a device that they can just plug into your wiring that remote checks the insulation on the cables is up to standards (in the UK we tend to call them a Megger tester, after the most common brand name, but I'm not sure what they'd be called in the US). This should be able to tell you if you've broken through the insulation to an extent that is dangerous. Hopefully, you'll be able to find an electrician that won't charge too much for this, or maybe even free -- it's at most a half hour job, and as it may well lead to rewiring work later down the line they'll probably want to get in before the competition.

There is also an inexpensive device you could use to see if you can detect a wire in the proximity you were drilling. Experiment with it where you know there is power, like near a light switch our outlet: https://www.youtube.com/watch?v=RbKCt0ahkp4 — rrauenza, Aug 22 '16 at 18:25

score 2 · Answer 6 · answered Aug 22 '16 at 08:25

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I'm thinking about something else than drilling into a wire. The power used by your drill could've been high and made the light flicker because it was nearly the maximum this power line could provide.

answered Aug 22 '16 at 08:25

user59144

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Since OP states a power outage of "2 seconds" it would be highly unlikely that the drill caused a 2-sec brownout in the house; far more likely is the assumption that they hit a live wire & should have a electrician replace the damaged section immediately. – Robherc KV5ROB Aug 22 '16 at 14:13
He didn't specify a "power outage" of "2 seconds", rather "the lights flickered momentarily for 2 seconds." Without further information it's really impossible to say what's happened.
And I guess I'm a tad lost, since when is the first answer for a DIY group "hire someone" ???
– Kevin_Kinsey Aug 22 '16 at 18:16
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@Kkinsey Since the OP indicated their preference to "call an electrician" if necessary. It'd be irresponsible to force / encourage folks to do potentially hazardous work that they clearly implied they aren't comfortable with. Sometimes a professional is desired, the wise realize that. – Jason C Aug 22 '16 at 18:39
While I agree with the need for safety, "clearly implied" is an oxymoron. Clarification is needed. – Kevin_Kinsey Aug 22 '16 at 18:44

rbarraud · Answer 7 · 2016-08-23T07:43:08.670

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Yes. Be very worried.

Keep everyone away from the closet/hole...

When you can, turn off the house's main isolating switch, and make sure nobody can turn it on while you work.

Tape over the hole with electrical tape. Leave the mains switched off if you can.

CALL AN ELECTRICIAN to repair the damage you've done to the wiring.

edited Aug 23 '16 at 07:43

answered Aug 23 '16 at 07:35

rbarraud

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score 0 · Answer 8 · answered Aug 22 '16 at 18:43

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You can obtain a wire tracer like this one. It might cost about as much as the time to knock a hole and repair it, but it should be quicker.

answered Aug 22 '16 at 18:43

Kevin_Kinsey

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Drilled into studs, light flickered momentarily but everything else seems fine now - should I be worried?

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