Re: 220 is considered "safer"

Post #14,596 by a6l6e6x 10/22/01 1:43:02 PM Reply	Re: 220 is considered "safer" Safer? Come on, now. If you put 220 volt probes between some two points on your body, you will carry twice the current and dissipate 4 times the power (V * i). Unless of course the power source cannot supply that much power. The big advantage of 220 volt is that, as you point out, for given power needs you need half the current and the wires can have 1/2 the cross-sectional area (i.e. less copper). That is the reason power transmission lines run at very high voltages. Of course, here in US, water heaters, ranges, ovens, heat pumps, etc. usually do run at 220 Volts. Alex Men never do evil so completely and cheerfully as when they do it from religious conviction. -- Blaise Pascal (1623-1662)
Post #14,607 by jb4 10/22/01 2:13:17 PM Reply	Hrm??? If I have a circuit in my house with a 15A breaker in it, It can deliver 1800 watts before the breaker opens. (120 V * 15 A). That same circuit in Germany would only require a 7.5 A breaker. That's half the current. jb4 (Resistance is not futile...)
Post #14,615 by Andrew Grygus 10/22/01 2:33:35 PM Reply	He's right on safety. Twice the voltage will push twice the current through your body. Since your body resistance is far too high for even 220 to push 7 Amps, that breaker will not blow. In any case, it isn't the current that kills, it's the fact it's AC. The 60-Cycle (Hz, for you newbies) frequencey messes up your heart beat, so only a few miliamps is probably enough to kill you, but 220 will do it more surely than 110 under less than ideal conditions. Using 220 volts instead of 110 is purely a matter of using less copper, not safety. [link\|http://www.aaxnet.com\|AAx]
Post #14,621 by Ashton 10/22/01 2:55:37 PM Reply	Then too: you actually have 220V coming in.. From the pole (or underground) transformer, with a ground center-tap for 2 X 110 circuits within the house A zealot could obtain (for most things) 220V rated appliances, even bulbs (just change the sockets and use Euro lamps). You could 'save' some copper too! - at negligible expense of frying self with bathroom heaters + wet bodies - in a trice instead of longer, slower. Kids + paperclips (or equiv) already manage to off selves with 110 - I shudder when in UK.. at equivalent risk made much larger. A. PS - last I heard, the best guess for lethal current directly across the heart: is quite less than one milliamp - no one wants to volunteer to see if it's really as low as ~ 100 microamps, for certain hearts and susceptible ones. (With all the parallel paths - this is not the same as "arm to arm" volts VS resistance / impedance, of course - that frequent connection point may be where the 'few milliamps' figure comes from.)
Post #14,668 by CRConrad 10/22/01 7:16:43 PM Reply	Isn't that exactly Edison's old anti-Tesla PR you're burpin?
Post #14,672 by Ashton 10/22/01 7:44:09 PM Reply	Yabut.. that's a can o'worms anyway. I'm by no means an expert on physiological effects of DC, AC and pulses, but have worked with and around the mix, and experienced various 'kinds' of shocks. Heard the caveats and saw a few cases where they weren't heeded. As you are doubtless aware (would I disbelieve a sig? ;-) Edison was in deep shit re the ^&#$ wiresize to get his DC sent all over the place, and T. 'solved' that cold / but with er side effects*.. Hence the pre Waggener-Edstrom spin about electrocuting elephants and such. (Did we really think those Wag-Ed droids were smart enough to invent spin? And they majored in Marketing!?) Anyway, PBS, BBC have shown various documentaries over here re the big brouhaha, the difficulties of Tesla (who worked briefly with Edison.. couldn't at all cotton to The Great One's tendency to assimilate and exterminate, so left.) Great soap opera 'bout the corporate mindset and greed generally. Tesla was fun - wish I could have seen that Colorado lab making lightning all around the building. Makes our puny 500 KV (DC) C-W generator pretty tame. Ashton
Post #14,695 by Andrew Grygus 10/22/01 9:54:42 PM Reply	The very one - but Tesla pulled the wool . . . . over the eyes of the press with an "AC Current" safety demo where the AC he used was in RF range, so the current travels only on the very outside of the conductor (his skin, in other words). This killed Edison's campagn, but it didn't negate the fact of the newly installed AC electric chair at Sing Sing prison. [link\|http://www.aaxnet.com\|AAx]
Post #14,729 by Ashton 10/23/01 3:20:37 AM Reply	Yeah, wasn't that sneaky? - out M$'d M$..
Post #14,738 by CRConrad 10/23/01 6:29:14 AM Reply	But the POINT is, DC would have fried 'em just as well!
Post #14,780 by Andrew Grygus 10/23/01 11:24:21 AM Reply	"Fry" is the operative word here. The objective of Sing Sing prison was to eliminate the smoke, smell and sizzle of a powerful DC jolt by using a lesser AC one that stopped the heart. How successful this was would require comparative experimentation, which I do not care to engage in at this time (though captured Taliban might be good research subjects). [link\|http://www.aaxnet.com\|AAx]
Post #14,655 by imric 10/22/01 5:49:41 PM Reply	It's the waveform. IIRC from my days in electronics shop, building power supplies, 110 is 1/2 of the 220 waveform - it 'looks' like a series of pulses. 220 is the complete wave. I think. I do remember that getting hit with a 110 jolt tends to be more painful than a 220 jolt from my days on the farm... And no, we didn't farm electricity... Imric's Tips for Living Paranoia Is a Survival Trait Pessimists are never disappointed - but sometimes, if they are very lucky, they can be pleasantly surprised... Even though everyone is out to get you, it doesn't matter unless you let them win.
Post #14,656 by Ashton 10/22/01 6:09:16 PM Reply	Umm sorry. No. Think you may be confusing the demo of what a rectifier does: clipping off the top (or bottom, depending on polarity of diode) of the nominal sinewave. It really IS twice the voltage (well, the "RMS" - root mean square of the nearly-sine waveform). Because it is, Ohms law sets the plan for what happens to current across a resistor (but NOT: what happens across reactors, either capacitive or inductive). Have only hearsay and a few experiences ~ how the body reacts to various pulse and other odd waveforms, but I'd be surprised if someone hasn't studied that at length. Believe me (!) you WILL notice the difference, getting across 110 or 220 - with the same sweaty palms, that is. It's pretty weird stuff anyway. Can kill you with a D cell (maybe now, with improved AA-cell?) - if I can choose the osc. / step-up transformer, capacitor size, and drain the sucker into that cap: then across those same sweaty palms. We're kinda fragile in that sense :[ If you ever have to work around more than PC circuit board 'electricity', you respect it or - Ashton
Post #14,663 by imric 10/22/01 7:06:41 PM Reply	Ah, yes. What I was thinking of was single phase, (Curse you for making me drag this out of my brain!) - which is compared to a [link\|http://www.3phaseconverters.com/u&s_elect.htm\|pulsating shower head here]. That's why single-phase hurts more (and is more dangerous?) than 'industrial' 220 (what we used on the farm)... Imric's Tips for Living Paranoia Is a Survival Trait Pessimists are never disappointed - but sometimes, if they are very lucky, they can be pleasantly surprised... Even though everyone is out to get you, it doesn't matter unless you let them win.
Post #14,669 by Ashton 10/22/01 7:29:15 PM Reply	Ah well.. now yer gettin fancy Yes, was thinking only single phase - but if you had 220 AC 3-\ufffd on farm (or businesses with lots of HVAC, say) believe usually that enters building at 440 (!) maybe sometimes 660 VAC. Thus you still have a virtual ground re. splitting into 2? 3? "220" legs. But here I have no personal experience (getting across such, that is - just 600-700 V. from a chassis PS xfmr. once). However you slice it though, it is all lethal territory; you escape only if skin was pretty dry and contact points not across the chest. Ditto 110-20 with wetter skin. Survival rule when feeling in places with (supposedly) insulated wires - keep one hand in pocket! and keep palm, fingers extended straight. Then if you hit something, you can pull straight back (and the body WILL do that!) If fingers curled around a source? Your muscle reaction will lock the curled fingers and pull you into 'better' contact. Most injuries in industry occur from the reaction to the shock - many more than electrocution - the violence of the body's reaction can easily fracture bones, all depending on what objects are nearby. Flying across the room is not unusual, not just Hollywood stuff.. Please.. don't try this at home :-P
Post #14,673 by imric 10/22/01 7:58:09 PM Reply	grin You'd think! you escape only if skin was pretty dry No such luck. Most of the 220v I got was when I was working on water pumps... Believe me, 110 single phase hurts - the 3-phase was only uncomfortable, by comparison. Survival rule when feeling in places with... Good rules - here's another: If you are sufficiently casual about getting shocked so that you feel compelled to test whether a wire is live by hand (this attitude is not uncommon among farmers), brush it with the back of your hand - so that if your hand clenches, it breaks contact with the wire. Your muscle reaction will lock the curled fingers and pull you into 'better' contact... ...Most injuries in industry occur from the reaction to the shock Heh - happened to my Dad! Something went wrong with an old circular saw - all metal, it got 'hot'. Dad had to swing the thing around HARD to throw it away from his grip... He was VERY lucky he didn't kill himself with the saw, more or less die from electrocution! It WAS pretty funny, though (he laughs himself... We have an odd sense of humor in our family, I guess). Imric's Tips for Living Paranoia Is a Survival Trait Pessimists are never disappointed - but sometimes, if they are very lucky, they can be pleasantly surprised... Even though everyone is out to get you, it doesn't matter unless you let them win.
Post #14,677 by Ashton 10/22/01 8:16:29 PM Reply	Migawd.. it's in your genes! Workin with wet (in service) water pumps Live? {sheesh} no wonder farming is #1 in accidents - er, willful suicide plays. Get thee to an unwired wooden building and.. power everything with propane. <<< (Or - buy a motorcycle; at least have some fun first!) Ashton PS yeah, back of hand is good too. But neon pencil-sticks are rilly CHEAP, y'know? {sheeshes} And some gadgets will give an emf warning without touching wire, through the insulation. Go thou and sin no more.
Post #14,682 by imric 10/22/01 8:34:33 PM Reply	Ya ever shake hands with a farmer? Count the missing fingers... And farmers can be just as smart as anyone - in fact, most of the farmers I know are part-plumber, part-electrician, part-carpenter, part-heavy-equipment-operator, part-vet, part-mason, and part-mechanic... Nothing can wait, on a farm, and farmers are kind of, well, desensitized to pain first, then what might cause pain, by extension. I loved living on the farm. I don't ever want to be a farmer. Imric's Tips for Living Paranoia Is a Survival Trait Pessimists are never disappointed - but sometimes, if they are very lucky, they can be pleasantly surprised... Even though everyone is out to get you, it doesn't matter unless you let them win.
Post #14,686 by Ashton 10/22/01 9:05:57 PM Reply	My uncles ran a machine shop. I recall driving into 'the city' with my aunt, gramma - about age 7? on occasion of one uncle separating from a finger. (This was from, maybe a 'ranch' but not really a farm; animals though, and real live food.) I asked him the usual 7-year old question: did you cry? Can see him now, doin a good Jimmy Durante performance of Cry !! why they could hear me into the next county !! Loved It, and him. While still not used to having to count to 9 (no re-attaches in the dark ages) .. he was willing to get a giggle out of a kid. Class. Dunno what it's like trying to farm now, compete with Ag-Biz and MBAs, just to live [but can guess] - but my experience of this 'ranch' was.. what could only be an oasis vs any Corp imaginary job. The chores were in fullest sense - educational and healthy.. but a lot more, esp. for a kid. Anyone who imagines farmers as dumb - is stupid, and an ass besides. They know more useful shit (about shit too!) than a bevy of PhDs. Cheers, Ashton at least, back in their territory - with a neighbor doing 'original stuff' ~~ organic farming; developing educational methods to spread it around, while doing it. Great soil here. Just picked my own figs and some of his (last) tomatoes that taste like tomatoes.
Post #14,689 by broomberg 10/22/01 9:26:26 PM Reply	Expensive mistake Oh, to have all this electrical knowledge. As opposed to me, who screwed up and ordered a pure 220V UPS, and am unable to return it. Really. I've got a computer room filled with both 110 and 220 gear. But since I typically deal with 2TB, 4 Sun 450s, and 6 Linux boxes at a time (including power), I will get several UPSs for each project. I like APC MX5000 Extended Run, which I typically get via CDW: [link\|http://www.cdw.com/shop/products/default.asp?EDC=079017\|http://www.cdw.com/...p?EDC=079017] But there is a model listed MX5000, exactly the same (or so I thought), but is the pure European model, which means these wierd 220V plugs (but only a piddly max 15AMP per plug, I use 30 amp 220V for my big boxen). CDW told me to jam it, they weren't taking it back. So I've blown about $7000 on 2 of them. I'l scavenge the battery portion and daisy chain them off another one, but the main unit is a waste. Oh well.
Post #14,731 by Ashton 10/23/01 3:43:25 AM Reply	Well.. one possibility If it's the ~pure sinewave version: 2:1 step-down transformer - though it will be a bit hefty at 3 KW/plug. This won't work for the modified-square-wave of the usual output, intended for switching PS's. (Dunno if Sun uses linear PSs, for some of their ovens?) (I can't quite see why they'd be unwilling to take it back unused, though. Especially ordering in that league) Let me know if you plan to toss the guts, please - though I haven't any immediate ideas for use of such a gadget.. Ashton
Post #14,880 by Ric Locke 10/23/01 11:47:50 PM Reply	220 UPS outputs Check the PSs on your boxen. Many, many of the better quality power supplies nowadays are "universal input", allowing 85 - 245 or 95 - 265V inputs; just change the power cord w/IEC connector for the plug in country of choice. Cuts down on the inventory problems... I'd imagine anything as expensive as a Sun would have such a supply; huge numbers of relatively cheap PCs do. Even in cases of non-universal input, many still have the switch to allow hi/lo AC input [though it isn't the old-fashioned transformer windings; dunno exactly how they do it -- switching power supplies are black magic to me] And re: 110/220 -- the one that bugs me is three-phase. First off, why isn't three-phase more common? Wonderful power saver for motors; you could probably make a sizeable dent in base power consumption just by running refrigerators on three-phase power instead of using shaded-pole motors, and my God the air conditioners. Here in the US we use "Delta" -- the three phases are arranged in a triangle. When it comes onto a premises, there's a ground in the middle of one side. Each side is thus 220 with respect to any other point, but reading from ground, you've got 110, 100, and the "wild phase", 208 volts. Trouble with that is circulating current; if the transformers don't exactly match, current flows around the loop, accomplishing nothing but heating the air. Other countries use "star" (also called "wye"), in which ground is the center and the three windings branch off, not interconnected. No circulating current, better efficiency. 110V three-phase wye would yield about 190V phase-to-phase, and running all three phases would (if the equipment were available) improve efficiency. Is it all a case of coping with legacy (=antique) gear? Regards, Ric
Post #14,697 by static 10/22/01 9:58:21 PM Reply	3-phase voltages. First of all, Australia's standard is 240V RMS AC. We are one of the few to remain at 240 instead of dropping to 220. Anyways. 3-phase voltage is usually referred to by the phase-voltage. For 240V, 3-phase is 415V. (For some reason, I seem to remember that 220V is 400V in 3-phase.) Wade. "All around me are nothing but fakes Come with me on the biggest fake of all!"
Post #14,737 by CRConrad 10/23/01 6:27:35 AM Reply	Huh? We just went TO 240, from 220! (BTW, hi--volt was 380v)
Post #14,742 by static 10/23/01 7:06:58 AM Reply	Just went to 240V...? That's very ... interesting. Maybe the forces trying to get 220V standardisation have been somewhat reduced in eficacy. Wade. "All around me are nothing but fakes Come with me on the biggest fake of all!"

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