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Thread: Off-Topic: US Electricity

  1. #1

    Question Off-Topic: US Electricity

    Maybe you're surprised from the thread name, but I'm curious about one US speciality (no, U-Turns, I'm not talking about you!) that is close to my field of work. And I found every single answer I needed to know in last decade, so, let's try it even for this one.

    OK, here it is: we all know there is 110VAC in US sockets (and 220-230VAC in Europe), but it is a combined or phase value?

    Why I'm asking? Somebody told me a story there is a clever idea behind it - in case it's 110VAC combined (between phase to phase) you can touch a single phase to ground, so you're under 100VAC (phase to ground is smaller than combined) and you should be safe.



    PS: I touched 230VAC twice - as a 4yo boy (sticked tie end to the little hole there) and as a MSc. from high voltage electrotechnics with 4 years of experience in high power lab during reparing toaster...

  2. #2

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    110VAC is a phase, 220 is the combined if I'm reading this right.
    https://www.quora.com/Is-the-power-s...235VAC?share=1

    Voltage of 120/240 comes from a standard single phase system, with two hot legs coming from the transformer, each being 120 volts to neutral, where the AC sine waves are 180 degrees out of phase.

    But many industrial facilities use 3-phase power because it’s more efficient. A 3-phase Y system (there’s also a 3-phase Delta system) has 3 hot legs, each of which is 120 volts to neutral, and each of which is 208 volts to one of the other legs. Each leg’s AC sine wave is 120 degrees out of phase.

    Because 3-phase power is more efficient, some utilities use it to supply residential properties too. So there will be a central transformer with a 3-phase Y system, and each home will have 2 of the 3 legs of that system, plus the neutral. To keep things balanced the missing leg will alternate among the properties served by that transformer.

    There are some downsides to the homeowner with this type of system. An air conditioner is only going to see 208 volts instead of 240 volts, so it will have to work harder at the lower voltage. But pretty much all equipment is rated for either 240 or 208 volts, so it will be OK. Also, on a multiwire circuit the neutral wire will always see some current (you need to understand what a multiwire circuit is to make sense of this issue).
    My last Electrical Engineering class was over 20 years ago, though...
    Historical Consultant/Researcher, Wings and Sails lines - Unless stated otherwise, all comments are personal opinion only and NOT official Ares policy.
    Wings Checklists: WWI (down Navarre Nieuport, Ares Drachens) | WWII (complete)

  3. #3

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    Single phase 120 VAC or Two phase 220 VAC both CAN KILL YOU! You should never touch two phases to each other (Phase to Phase fault) or touch a phase to ground (Phase to Ground fault). This can cause fires, explosions, and electric shock. 120 Single phase is less deadly, but it can still kill. There are deaths every year from people getting killed by house hold electric and electric appliance issues. I work with electricity for a living. I have had my share of zaps....they do not feel very good! I have also seen the results of bad accidents where people have died. Please be safe when working with electricity!!!

  4. #4

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    I'll echo Dan's caution... first thing at the start of every quarter in the Electronics lab, my instructor would make everybody kit out in safety gear, put a hot dog next to a huge capacitor and blow the cap as a demonstration of what just one simple mistake can do. And I quote, "the SECOND you do not respect these things they KILL you."
    Historical Consultant/Researcher, Wings and Sails lines - Unless stated otherwise, all comments are personal opinion only and NOT official Ares policy.
    Wings Checklists: WWI (down Navarre Nieuport, Ares Drachens) | WWII (complete)

  5. #5

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    Thanks for the answer, I was curious If I remember this well.

    To the second (safety) part: believe me, nobody underestimates electricity here. I was working with voltage up to 50kV and my "personal record" on Short-Circuit test is about 200kArms with 500kAp (ultraasymmetry, but of course of LV) (+/-, do not remember exactly) during testing a busduct for a Polish client. Safety always first, no kidding, there is literally no other way. The story about toaster is only as a reminder that most of injuries happened at home when you not expect it (lost my concentration and forgot to unplug it before the third opening, completely my mistake).
    Of course, capacitors are "silent killers" and everyone should be twice as careful as assual during working with them.

  6. #6

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    I removed the top panel of a rented washing machine when it malfunctioned - as I reached for the circuitry all the hairs stood up on my arm, then I was thrown across the kitchen by the force of the juice!
    Didn't lose consciousness, but it did hurt!

    I assumed I was immune to electricity, having been hit by lightning on a golf course several years before, and survived.
    I laugh in the face of danger - then I hide until it goes away!

  7. #7

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    Quote Originally Posted by Flying Helmut View Post
    I removed the top panel of a rented washing machine when it malfunctioned - as I reached for the circuitry all the hairs stood up on my arm, then I was thrown across the kitchen by the force of the juice!
    Didn't lose consciousness, but it did hurt!

    I assumed I was immune to electricity, having been hit by lightning on a golf course several years before, and survived.
    I knew you weren't easily shocked!

  8. #8

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    Wow, Tim, so you are officialy a superhero! Do you remember how did you feel after that lightning strike?

  9. #9

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    From all my experience with electricity, it isn't the voltage that kills you, it's amps through the heart.

    I have had 50,000 volts and 20,000 volts go into my arm from static discharges (capacitor discharges, thankfully, not sustained current), and I was using my right hand, standing on rubber mats with my other hand not touching a ground. Survived both of those. "Left Hand in Pocket" Rule when testing live circuits!

    These events were in environments where safety rules were in effect, and just single point mistakes or failures. If all the other safety procedures had not been observed, the outcomes might have been fatal.

    So, North American voltage at 120 volts, 60 hz, or European voltage at 220 volts, 50 hz, carelessness can kill you, but probably because it goes through your heart with a minimum of a 1/4 amp.
    Mike
    "Flying is learning to throw yourself at the ground and miss" Douglas Adams
    "Wings of Glory won't skin your elbows and knees while practicing." OldGuy59

  10. #10

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    Quote Originally Posted by Ajay View Post
    I knew you weren't easily shocked!
    I laugh in the face of danger - then I hide until it goes away!

  11. #11

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    Quote Originally Posted by Dan-Sam View Post
    Wow, Tim, so you are officialy a superhero! Do you remember how did you feel after that lightning strike?
    Things were very disjointed...

    I hit the ball with my putter, then had a bad dream about being kidnapped (me in the ambulance, throwing up over the crew!), then awoke on a cold rubber-covered trolley in a darkened room, under a blanket, with no clothes and with superficial burns and a pounding headache.
    They kept me in for observation over night, then I went home to recover.
    I laugh in the face of danger - then I hide until it goes away!

  12. #12

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    Quote Originally Posted by OldGuy59 View Post
    From all my experience with electricity, it isn't the voltage that kills you, it's amps through the heart.
    That's right - the potential difference in volts can be huge, but if those volts aren't moving (amps!) it's not nearly as dangerous as people are led to believe.
    I laugh in the face of danger - then I hide until it goes away!

  13. #13

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    Quote Originally Posted by Flying Helmut View Post
    Things were very disjointed...

    I hit the ball with my putter, then had a bad dream about being kidnapped (me in the ambulance, throwing up over the crew!), then awoke on a cold rubber-covered trolley in a darkened room, under a blanket, with no clothes and with superficial burns and a pounding headache.
    They kept me in for observation over night, then I went home to recover.
    Seriously? They thought you're over?

  14. #14


    I'm learning to fly, but I ain't got wings
    Coming down is the hardest thing

  15. #15

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    Reading this thread reminded me of something I once read about how people learn about electricity:

    Some learn by reading about it.
    Some learn by direct observation.
    The rest learn by peeing on the electric fence for themselves.

  16. #16

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    Quote Originally Posted by Dan-Sam View Post
    Wow, Tim, so you are officialy a superhero! Do you remember how did you feel after that lightning strike?
    Tim’s super powers gained:
    1) sniffing out the best deals on eBay
    2) painting small things with ease

    Hell of a story!

  17. #17

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    Quote Originally Posted by Flying Helmut View Post
    I removed the top panel of a rented washing machine when it malfunctioned - as I reached for the circuitry all the hairs stood up on my arm, then I was thrown across the kitchen by the force of the juice!
    Didn't lose consciousness, but it did hurt!

    I assumed I was immune to electricity, having been hit by lightning on a golf course several years before, and survived.
    Gives a new meaning to "Flying" Helmut. LOL! Seriously though, I am glad you were not serious injured or killed!!!

  18. #18

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    Just look up Arc-Flash on youtube and you can see lots of wonderful explosions due to phase to phase and phase to ground faults in industrial settings. Makes you think! Just went through my Arcflash refresher at work this week.

    https://www.youtube.com/watch?v=PO6see7_ODY

  19. #19

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    my mom got struck by lightning twice. she has no memories of either incident that she was able to relate. shes a bit "off". after the childhood one, according to grandma. she was sitting there with her mouth open screaming, but sound would only come out intermittently in a regular pattern.
    i was there for the 2nd time though i was 3-4 so my memories are a bit vague. she was washing dishes at the sink, and i was sitting in a high chair by the table a few feet away. lightning struck the transformer in the back yard which exploded and sent a ball of lightning into our kitchen window into the sink where mom was washing dishes. i dont recall what happened to mom next but i do remember the electricity arcing to the table i was sitting at which was metal framed. it then arced over the table for a bit. i remember thinking how neat it looked and reached out to try and touch it. luckily for me it was out of my reach!!!

  20. #20

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    Phillip! That is pretty insane! Glad you couldn't have reached it!!!!! Luckily nobody died!

  21. #21

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    That is an incredible story! Thanks for the share.



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