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B Got zapped in a strange way

  1. Apr 13, 2016 #1
    Hi,

    So I was just vacuum cleaning the carpet in my room , I have wooden floor and the overall air is rather dry and warm.Normally I get static electricity buildup when vacuuming because the small dust particles that go through the cleaners pipe build up charge on the plastic pipe , I assume some charge settled on my skin and since i have wooden floor it stayed on me , then I switched off the vacuum cleaner and with my one hand wanted to move out of the way the power cord going into the cleaner , as I touched the cord it zapped me but not with the usual static kind of "zap" but with a bit more of something similar to an AC tingle which I am familiar with since i have been electrocuted from mains AC before.

    My question is is it possible that the high voltage static charge kind of broke down the insulation of the cable and he charge found its way into the neutral conductor back into the mains socket which was something like an earthing rod for the HV charge ?
    the cable is otherwise fine and has never caused any problems but this accident was strange.
    It's hard to say for sure because this shock wasn't like the ones I have gotten from bare wires but still it felt like a small vibration passing through my arm into my leg.

    what's the chance of that being a real shock or maybe my nerves simply giving me a false feeling of vibration which I have gotten a few times were electricity has been nowhere near.
    also if for example the insulation of the wire was indeed vulnerable and the static high voltage charge did pass through it how much of a current was there ? once more the fact that I was on a wooden dry floor , I assume the current there was extremely small but since the voltage was high it simply gave me a feeling yet after i checked my pulse and it was just a bit higher and that was probably from the shock feeling.
     
    Last edited: Apr 13, 2016
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  3. Apr 13, 2016 #2

    Vanadium 50

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    Really? And you got better? :oldsmile:

    This actually gets me to my answer - that was imprecise writing, and I think the issue is imprecise feeling. I don't think it is likely that the human body is a sufficiently accurate detector of voltage and current to exclude a static electricity event for what you observed.
     
  4. Apr 13, 2016 #3

    davenn

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    haha, that was my laugh for the nite ... nice response :smile:

    @Salvador .... people don't recover from electrocution

    But as V50 said .... and I agree, it was most likely static discharge


    Dave
     
  5. Apr 13, 2016 #4
    well English is not my first language so I really didn't get the yoke about what I said , to me electrocution is when you get a severe electric shock isn't that the case?
    I said that because in the past I have had accidental contact with bare live wires and gotten a real shock , like the one when I was a kid and touched the live 230v phase with my finger because back in the day I simply wanted to know whether the wire was " on" and after that I couldn't feel my legs for some minutes since the current passed through them into the concrete floor.
    just for grammar how would you call the case I just described ?


    As for what happened today , well I'm not sure, it definitely wasn't something very dangerous as compared to the things i've gotten into at other times but I am not fully sure about the properties of older rubber wires when it comes to situations like these.
    for example back in the day my grandmother had this old washing machine that had a manual turn on/off switch , rather big mains switch, the device itself was made in the 60's and she always used a wooden peg to push the switch because every time one touched it with bare fingers you could feel this little yet sensible feeling of AC.
    also back in school I was working on an electric lathe powered from 3 phase mains which also had this old switch and once I too got a small zap the very moment i pushed the switch on.
    and what is definitely true is that my old refrigerator has this aluminum side wall and if I barely touch it with my elbow I can feel this little tingle so i once took a simple multimeter I had and simply measured across a span of that aluminum wall and guess what there was some 16 to 20v AC on it.
    the same weird thing goes for a SHARP lcd tv I had , the plastic maybe not so plastic side plate which goes on both sides of the screen sort of gave me this small tingle when i once touched it again I took the meter and turned it to AC and put one probe on the tv and the other on my radiators which are grounded and guess what 16v AC.

    I could keep on and on about all these observations but Vanadium are you really sure about the bodies capability of sensing electric currents ?
    I have seen in my life when together with these older electricians that some can literally touch the live ac phase with the tip of their finger and simply say Oh this ones switched on while some others get killed easily with much lower voltages.
    It seems humans really do differ in this sense.Well I guess I have asked an unanswerable question so I will have to do some testing with vacuum cleaner wire myself.
     
  6. Apr 13, 2016 #5

    davenn

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    no, well severe yes, but if you get electrocuted, you are dead
    if you just get a zap, then you got an electric shock

    maybe that will help you see the reason for the comments above :smile:
    sorry for having a little giggle at your expense

    anything like that should be checked out by a qualified electrician as it is not safe

    I have seen stuff written in the past and even on the PF forums about what minimum current at a specific voltage is required to be able to be felt
    I am sure if you did some googling you will find some good answers ... look for reputable links ... there's lots of garbage out there

    not a wise thing to do .... it could easily kill them one day ... maybe they were working with 110V AC, USA and some other countries
    still dangerous but a little more forgiving

    you definitely wouldn't want to do that in the UK, Australia or NZ and a bunch of other countries where the mains voltages can be anything from 220 - 240V AC
    the chances of electrocution is much higher

    it's all quite variable, even for a single person and where on the body the electrical contact happens ....
    skin thickness, how damp or dry it is are 2 important factors


    cheers
    Dave
     
  7. Apr 13, 2016 #6
    Ok I see about the terminology , good to know next time I wont tell my foreign friends I'm a walking dead man :d

    as for the other factors , I don't have a diploma from a school in electronics but I have been around working with it for basically most of my life and as for the washing machine switch there was nothing there except an old switch with probably degraded plastic.there were no moisture no minerals or other things that could have made a current path from the inner contacts of the switch to the surface outside plastic cover push button.It's like chasing a ghost much like what happened today , I will probably never know what exactly it was but as for the switch it simply got replaced and the problem went away.
    and the feeling of AC only happened during the very turn on or off of that switch if you touched it when it was already connected nothing happened , much like when I pushed the lathe switch in school I felt this small jolt biting my fingers at the very instant the inner three contacts connected each of the phases to the motor.

    I live in northern Europe so we all have 230VAC , when I actually measure it's usually closer to 240.and the incoming single phase supply is actually just one out of three phases since the common supply that comes into the apartment building is 3 phase so the current rating at those 240V is quite big , If I had the misfortune of being attached to a live wire long enough I think I would cook myself to flames.
    I assume the human body resistance is not low enough to trip the automatic breakers if for example I hanged over with one part of my body o the phase and the other to some earthed part like a water pipe.

    but still I would love to know if someone has ever had something similar were a insulating part gave a small zap that could be felt , like a piece of older wire or a switch etc ?
     
  8. Apr 14, 2016 #7
    Air moving through a plastic pipe can build a significant static charge, with or without particles entrained in the air stream (25,000 volts is not uncommon). If you are in contact with the pipe part of that charge can transfer to you. These charges can get very high. You could have touched the power cord where the insulation has broken down somewhat, allowing the static charge to arc to the neutral. The cord could still be perfectly safe to use at 120V or 220V. It could be simply that the cord has some conductivity on its surface due to surface contamination with dirt.
     
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