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May 17, 2010 11:41 AM   Subscribe

Why do I feel electric currents?

Starting about a year ago, I began feeling electric currents in the metal surfaces of appliances. It could be anything that was plugged in: the range top, a toaster, my computer, a radio, a desk fan... If I touched it lightly, I could sense a slight tingle. If I stroked my finger across the metal, it felt like it was vibrating. A strange, tingly sort of vibration. That's the best way I can describe the feeling. If I turned power to the appliance in question off, the feeling went away.

At first, this frightened the bejeebus out of me. The first place I felt it was the range top, which is rickety and old. My pans are stainless, and when I touched them, I could feel the electric vibration in the handles. I called my homeowner's insurance (since the range top was still covered under home purchase warranty) and told them that the range was bleeding current and shocking me (indeed... if I grounded myself properly...shoes, etc...or if handled my pans with a rubber mat, I felt nothing). They sent somebody out who could not find anything wrong.

The next major incident was when I was building my current PC. The power supply kept vibrating with current, and I was afraid it was defective. I took it back to exchange for another. The store tested it and found nothing wrong, but swapped it out for me anyway. When I got the new one home, it vibrated when plugged in, too. Unplug it, and it still vibrates for a second while the capacitors lose charge, but it will eventually stop.

The craziest incident so far was when I was working on my laptop, but I was grounded well. My girlfriend, next to me, was not grounded. If I touched the laptop, and then touched her, *she* felt like she was vibrating.

Then I thought it was just my house and crazy wiring...but I started feeling it elsewhere, too. Elsewhere, but not everywhere. For instance, I never feel it at the office, I always feel it at my house. Other people's houses are about 60/40 in favor of feeling it...public spaces are about the same.

What gives? This is seriously weirding me out!
posted by kaseijin to Grab Bag (22 answers total) 5 users marked this as a favorite
Nerves are weird. Sounds to me like an appointment with a neurologist would not be inappropriate.
posted by valkyryn at 11:43 AM on May 17, 2010

For what it's worth, I feel it too (pretty much exactly what you described) – I always chalked it up to faulty wiring. It never struck me as something unusual.
posted by halogen at 11:59 AM on May 17, 2010

I would try to confirm or rule out the theory that this is being caused by electrical currents. I'd do this by using one of the appliances from your example (probably the toaster) that gives no indication whether or not it's plugged in. Connect it to a long extension cord going to another room. Have a friend you can trust to tell the truth plug it in and unplug it randomly. If the electrical currents theory is right, you should be able to call out when it is plugged in vs. not.

If you can reliably determine when things are plugged in or not, from only the sensation you're feeling when touching them, that calls for some further troubleshooting of the electrical variety. Having this happen in 60% of other people's houses you visit seems like an awfully high percentage of houses to have this type of stray voltage issue, though. I guess you could just be especially sensitive to that, since there is always some of this around.

Whereas if you find the effect is based more on you knowing whether something is plugged in or not, I suggest it's not an electrical problem, but neurological/biological/psychological. It may not be much of a stretch to feel something weird if you're expecting to feel something weird, right?
posted by FishBike at 12:02 PM on May 17, 2010 [3 favorites]

I've felt the same thing on occasion. I've assumed it's due to a device that grounds to the case being plugged into a miswired receptacle.

You can buy an electrical outlet tester at a hardware for about $10.00 that will tell you if there's issues like bad ground or reversed polarity when you plug it into an outlet.
posted by zombiedance at 12:05 PM on May 17, 2010

What FishBike said. The bit with your girlfriend is especially odd, and doesn't really fit the hypothesis that you're actually sensing electric currents.

Do some blind experimentation to make sure you're sensing electricity and not just sensing the expectation of feeling electricity.
posted by ook at 12:10 PM on May 17, 2010

I've felt it too, most notably on my macbook pro when plugged in, on concrete floors, in bare feet.
posted by a halcyon day at 12:13 PM on May 17, 2010

Response by poster: I'm pretty sure that it's not a psychosomatic thing, as it has completely surprised me at times and I have also already done the "hey plug this in but don't tell me" test. The girlfriend incident up there was one such big surprise. It has to be some issue with grounding and wiring...but why am I feeling it when nobody else around me can?

Are some people more sensitive to currents?
posted by kaseijin at 12:20 PM on May 17, 2010

1. Electric fields move hair quite easily. More hair = More movement = More to sense. Try touching with your elbow rather than fingers.
2. Hydration. You could be a better conductor than most. Try drinking less fluids for a day and see if it changes at all.
posted by jwells at 12:33 PM on May 17, 2010

It has to be some issue with grounding and wiring...but why am I feeling it when nobody else around me can?

Are some people more sensitive to currents?

Yes, there's some variability in sensitivity to currents, and also variability in how well different people conduct electricity, and even variability in the same person depending on things like skin dryness, exact path the current takes, and so on.

Do you have a digital multimeter that measures current? If so, maybe the next thing you can try to do is quantify the amount of current flowing between these objects and your hand. Set the meter on the AC milliamps (mA) measurement, and on the lowest range. Hold the metal part of one probe in your hand, and touch the other probe to one of the objects that causes this sensation (holding that 2nd probe by the plastic part).

Now the current will flow through the meter before it flows through you, and you'll get a reading of how much there is. You should even feel the sensation from the metal probe you're holding. It takes a substantial fraction of 1 milliamp (a few hundred microamps) to be felt in your fingertips, so if you don't measure that much, something else is going on. But if you do measure a significant amount of current flowing, you can then get someone else to repeat the experiment and see if the meter reports a lower number for them, or they're just less sensitive than you are.

Obviously do not touch anything with the meter probes that you would not normally touch directly with your hand (e.g. don't go sticking it in outlets and so forth).
posted by FishBike at 12:44 PM on May 17, 2010

I think the dominant way of thinking (at least in USian society) is that humans can only interpret sensory input if it's in one of the "classic" modalities (vision-light, audition-sound/pressure waves, somatosensory-pressure/vibration/heat, taste & smell-chemical composition), but neuroscience continues to support the notion that most sensory perception is moderated by multi-modal cortical/subcortical interactions.

There are cells throughout the brain (and especially in the hippocampus) that respond preferentially at specific parts of oscillations that are based on the summed electrical activity of a populations of neurons. That is to say, their 'receptive field' is at least partially oriented to electrical current/fluctuations.

In the superior colliculus, there are cells that are definitely electoceptive in nature, and not only to internally generated electrical stimuli, but to electricity in the environment.

tl;dr: Electoception is real, humans have it, and while it's not widely understood, it is totally reasonable that you perceive electrical currents in your environment.
posted by solipsophistocracy at 12:49 PM on May 17, 2010

If I lightly rub the lid of my (non-unibody) MacBook Pro while it's running, I feel exactly the same thing--what can only be described as a very, very subdued electrical pulse, like the thing is vibrating. My friend brought this to my attention, and he feels it too. I didn't think it was unusual.
posted by a sourceless light at 12:55 PM on May 17, 2010

Different people have different subjective experiences to the same amount of current. What most people experienced as tingling causes one person to yelp in pain.

I haven't tried this, but it does not seem to implausible that the "yelp in pain" subject could have been more sensitive to lower currents also.

I absolutely do not advocate repeating this experiment with detailed questioning about when people start to sense any slight tingling sensations before frightening them away from touching the equipment. Don't try this at home kids.
posted by yohko at 1:37 PM on May 17, 2010

I've felt this occasionally since childhood. It only occurs when my skin is actively brushing across the smooth metal surface of an electrical device (or something grounded to one, I find the metal trim of lighted glass display cases often causes it,) and I can make the effect go away by powering off or disconnecting from ground the device in question. For example I'll brush my finger across a metal lamp's body and notice it, then turn off the lamp and touch it the same without feeling the effect, then turn it on and it'll return. I definitely feel it with my aluminum MacBook. I don't think it's as simple as a ground/neutral swap, since it does seem to happen very frequently, and with outlets that could not possibly be wired incorrectly (because I wired them, of course.)
posted by contraption at 2:00 PM on May 17, 2010

My friend and I both get this from his older Macbook. I assume that it has some vibrating component - eg a fan.
posted by LobsterMitten at 3:00 PM on May 17, 2010

You're feeling the 50Hz (or 60Hz in the USA) "vibration" of the AC current supplying your appliances. You'll only feel it on un-grounded appliances. It's not harmful.

How much you feel it depends on how well grounded you are at the time.

It's common, though most people don't know what it is.
posted by Mwongozi at 3:10 PM on May 17, 2010 [1 favorite]

I've felt this, but only on one particular laptop. A MacBook Pro (so titanium case, I think), which is sounding like a fairly common experience. The one in question had recently had its insides tinkered with and I assumed that had something to do with it. It was a very unnerving sensation.
posted by Ginkgo at 3:13 PM on May 17, 2010

You're feeling the 50Hz (or 60Hz in the USA) "vibration" of the AC current supplying your appliances.

I tend to agree, it does feel like about 60Hz and does seem to be related to the presence of electrical current, but I still can't explain the way the sensation occurs only when i brush my skin across the surface and not when I hold it still, and why it doesn't feel like any electroshock I've ever experienced (I've been bitten by a wide variety of AC voltage sources, from household wiring to ~30V floating grounds in CATV systems to TENS systems to an especially foolhardy ~100kV teenage Tesla coil mishap. I'm more cautious now.) It feels more like my skin is rapidly catching and slipping as it drags across the smooth metal, like a wet finger will squeak across smooth rubber. It's not really like the tingle of current flow except in its frequency.
posted by contraption at 3:37 PM on May 17, 2010 [1 favorite]

It feels more like my skin is rapidly catching and slipping as it drags across the smooth metal, like a wet finger will squeak across smooth rubber. It's not really like the tingle of current flow except in its frequency.

Excellent, contraption, this is just how it feels to me, too, and is essential to my explanation.

I think you're not feeling current flow (except in a very minor way), but charge.

Why and how are you feeling this charge?

First, the surface charge on the object flips polarity in sync with the AC of the house wiring.

Second, you feel it as you drag your finger across the surface because you are charged, but your charge maintains a constant polarity; when your charge is the same as the object's charge, your finger slips because like charges repel, when your charge opposes the object's, your finger catches because opposites attract.

Why would you be charged up like that, though? Even if I could adduce a mechanism for it (such as hyperpolarization of some kinds of sensory nerve endings, or unusual electrical activity of certain muscle cells, say-- like the tiny muscle fibers that attach to hair follicles) it would be metabolically expensive to maintain your body in a charged state.

The only thing that occurs to me is that it could be useful to have a net charge on your body to help manage your interactions with floating particulates in the air, which can include pathogens like bacteria, bacterial spores, viruses, mold spores and pollens.

All these are generally said to be positively charged ordinarily, (I haven't found a page that states this and is definitive enough to link, yet), and so it could conceivably be worthwhile to be positively charged yourself and repel these particles, especially if you have allergies or asthma.
posted by jamjam at 9:01 PM on May 17, 2010

Did you buy new shoes? When I wear a particular pair of shoes on the carpet at work I can feel this too
posted by fshgrl at 9:49 PM on May 17, 2010

Me too. Lightly drawing a finger across the bare-metal surface of some (not all) plugged-in devices. A light vibrating feeling only where the skin touches the metal, and it goes away under any other circumstance: hold the finger still, touch harder, wet the finger, or unplug the device. And all this is with me insulated from any other metal surface.

With the digital multimeter, it shows 7 microamps AC flowing to my finger, and yes, I can feel the vibrations when I rub my finger along the meter's metal probe. Again, I'm insulated.

No sparks. No pain. Not feeling anything like an electric shock. Just that curious vibrating sensation on the dry skin.
posted by exphysicist345 at 10:42 PM on May 17, 2010

Response by poster: Yep. Contraption and others have it. That is *exactly* what I am experiencing.

jamjam's hypothesis is interesting...is it medically plausible? Any physicians on here want to chime in? Interesting that he touched on allergies/asthma, because I *do* have very severe asthma.

Curious also that I only started noticing this in the last year and a half or so, but it's totally the same thing others here are describing... a slipping, catching. quickly vibrating feeling when I lightly draw my fingers across certain plugged-in metal surfaces. (Except for the situation where I felt it on my girlfriend's arm while I was touching my plugged-in aluminum MacBook).

Could it maybe have to do with sodium intake, and the body's average salinity? Would that make some people better conductors than others?

Or are we just a super-race of electrically attuned meta-humans?
posted by kaseijin at 7:38 AM on May 18, 2010

jamjam's hypothesis is interesting...is it medically plausible?

Well, charge is relative, so your body wouldn't need to be holding itself at some unnatural level, just remaining at a constant charge while the surface of the metal changes back and forth. You also don't need to be especially conductive to be affected by electrostatic forces, in fact it helps to be non-conductive so the charges stay put (witness hair standing on end and latex balloons stuck to walls.) My very poorly educated guess follows:

An inductive element in the circuitry of the device is alternately attracting electrons (resulting in a high electron density in the device chassis nearest said element and a net positive charge on the skin of the chassis) and pushing them away (resulting in a net negative charge on the surface.) This alternation of the object's charge relative to the charge of your body somehow (*waves hands*) causes a rapidly oscillating change in the coefficient of friction between your skin and the metal surface.

Hopefully someone with a better understanding of electrostatics and friction can chime in to support or tear apart my conjecture.

Or are we just a super-race of electrically attuned meta-humans?

It's a subtle effect. I think it's more likely that everybody experiences it, but most don't notice it or dismiss it as the metal having an odd texture. I suppose having specially oily or wet skin might inhibit the effect.
posted by contraption at 9:23 AM on May 18, 2010

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