Physical Sensation When Driving by Electric Utility Fault/Arc?
August 21, 2015 5:48 PM Subscribe
While driving home from work yesterday afternoon during somewhat-cloudy daylight, I suddenly noticed a bright bluish glow on nearby objects, heard a loud hum that sounded like it had 60/120ish Hz components, and felt a strange tingling/vibrating sensation in my upper body. When I got home, I checked the power company's outage map and saw that there was a ~500-customer outage centered around the area where this happened, which started around the time I drove through the area. The stated cause of the outage was "equipment problem." Because of this, I am guessing there was some kind of fault in the roadside electric distribution system which caused all of this, and I have some questions about what might have happened.
I noticed the bluish glow (which looked like there was an intense light source, such as an electric arc, somewhere high enough above my car that I could not directly see it), heard the hum, and felt the tingling/vibrating sensation for somewhere between 2-4 seconds to the best of my recollection. I was going about 35 mph at the time, so I drove away from whatever was causing this fairly quickly.
Two things assure me that this was "real," as opposed to me losing my mind or something:
1) There were two people walking the opposite way from my direction of travel on the sidewalk. In my rear-view mirror, I saw them turn around and look upward, presumably at whatever was going on.
2) I was talking on a cell phone (hands-free) at the time. Right after I passed the area, the person on the other end of the phone asked what "that funny buzzing noise" was.
This is not a stretch of road I normally drive on, so I am not familiar with the electric utility infrastructure in the area. I looked at the entire stretch of road on Google street view, and I did not see any power lines that looked like they carried anything more than primary distribution voltage, nor did I see any equipment that appeared to be anything bigger than a "pole pig" serving a small number of residences.
There were a couple places where the primary distribution lines branched off at a 90 degree angle to the main line; I suppose that maybe you could get a phase-to-phase fault if a connection failed mechanically at one of those points.
So, my questions are this:
1) What could have happened in this kind of electric system which would have lasted for 2-4+ seconds without blowing a fuse or tripping a protective relay/breaker?
2) What do you think could have caused the vibrating/tingling sensation I felt? I have only a limited knowledge of electric power systems, but I can't think of any way that any fault on this kind of system could have caused an electric or magnetic field which would have been physiologically perceptible by me, inside a car on the roadway. Can you? Or is this most likely attributable simply to mechanical vibrations caused by whatever the fault was (an arc, maybe)?
I noticed the bluish glow (which looked like there was an intense light source, such as an electric arc, somewhere high enough above my car that I could not directly see it), heard the hum, and felt the tingling/vibrating sensation for somewhere between 2-4 seconds to the best of my recollection. I was going about 35 mph at the time, so I drove away from whatever was causing this fairly quickly.
Two things assure me that this was "real," as opposed to me losing my mind or something:
1) There were two people walking the opposite way from my direction of travel on the sidewalk. In my rear-view mirror, I saw them turn around and look upward, presumably at whatever was going on.
2) I was talking on a cell phone (hands-free) at the time. Right after I passed the area, the person on the other end of the phone asked what "that funny buzzing noise" was.
This is not a stretch of road I normally drive on, so I am not familiar with the electric utility infrastructure in the area. I looked at the entire stretch of road on Google street view, and I did not see any power lines that looked like they carried anything more than primary distribution voltage, nor did I see any equipment that appeared to be anything bigger than a "pole pig" serving a small number of residences.
There were a couple places where the primary distribution lines branched off at a 90 degree angle to the main line; I suppose that maybe you could get a phase-to-phase fault if a connection failed mechanically at one of those points.
So, my questions are this:
1) What could have happened in this kind of electric system which would have lasted for 2-4+ seconds without blowing a fuse or tripping a protective relay/breaker?
2) What do you think could have caused the vibrating/tingling sensation I felt? I have only a limited knowledge of electric power systems, but I can't think of any way that any fault on this kind of system could have caused an electric or magnetic field which would have been physiologically perceptible by me, inside a car on the roadway. Can you? Or is this most likely attributable simply to mechanical vibrations caused by whatever the fault was (an arc, maybe)?
A massive arc will do the things you describe without tripping the upstream breaker (for a while). This is especially true when the fault is in the breaker itself and the situation needs to get big enough to trip the even large upstream breakers.
posted by ryanrs at 6:07 PM on August 21, 2015
posted by ryanrs at 6:07 PM on August 21, 2015
Response by poster: ryanrs: The thing about those videos is that most of them (at least, the more spectacular ones) take place on transmission lines which run at 115+ kV. The highest-voltage lines on the street I was driving on are primary distribution lines, which run at 35 or fewer (typically quite a bit fewer) kV.
Also, how/why would an arc produce a tingling sensation? Some electric or magnetic field effect, or just mechanical vibration?
posted by Juffo-Wup at 6:14 PM on August 21, 2015
Also, how/why would an arc produce a tingling sensation? Some electric or magnetic field effect, or just mechanical vibration?
posted by Juffo-Wup at 6:14 PM on August 21, 2015
Everything is a capacitor, at least to some extent. Charging up capacitence with a big voltage (like 35KV) could produce most of those effects.
posted by Chocolate Pickle at 6:18 PM on August 21, 2015
posted by Chocolate Pickle at 6:18 PM on August 21, 2015
a transformer (maybe what you call a pole pig?) failed down our street. it was a fair away away, and some time ago, but i remember seeing various arcs and sparks over a good 10s, maybe more (and also, afterwards, a pool of black goo that had me worried about pcbs). i don't know the voltage here in chile, but this would have been whatever is used before the final step down for residential use. no idea why it didn't trip anything.
according to this site (see first interactive graphic - slide left hand "person" up) you feel a tingling sensation from hair movement at around 1kV/m. so if you were 10m from 10kV you might have felt it (although you say inside a car, and i would have expected that to work like a faraday cage, making the effect less).
posted by andrewcooke at 6:47 PM on August 21, 2015
according to this site (see first interactive graphic - slide left hand "person" up) you feel a tingling sensation from hair movement at around 1kV/m. so if you were 10m from 10kV you might have felt it (although you say inside a car, and i would have expected that to work like a faraday cage, making the effect less).
posted by andrewcooke at 6:47 PM on August 21, 2015
Response by poster: Oh, yes, sorry. By a "pole pig," I mean a small transformer which converts primary (<35 kV) voltage to household (120/240 V) for a small number, typically between 1 and 5, houses.
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posted by Juffo-Wup at 7:18 PM on August 21, 2015
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posted by Juffo-Wup at 7:18 PM on August 21, 2015
When those transformers blow, they're LOUD. They're also humming at a very low frequency (60 Hz, natch). One blew a few blocks away from my home and I could feel it in the floor.
posted by JoeZydeco at 7:32 PM on August 21, 2015
posted by JoeZydeco at 7:32 PM on August 21, 2015
Hm, that actually sounds a little similar to warning signs of an imminent lightning strike:
posted by losvedir at 2:04 AM on August 22, 2015 [3 favorites]
A close or direct lightning strike will sometimes give you a short warning a few seconds before the event, usually in the form of:Those are all results of a strong electric field so it's somehow related to your experience, though I'm not sure exactly how.source
- A soft or loud buzzing, clicking, hissing or cracking sound.
- A tingling sensation
- Hairs on the arm or head standing on end
- Nearby metal objects emitting a soft, blue-white glow called 'St. Elmo's Fire'
posted by losvedir at 2:04 AM on August 22, 2015 [3 favorites]
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posted by tilde at 6:07 PM on August 21, 2015