howard@tp2.Waterloo.NCR.COM (Howard F. Steel) (03/10/89)
In article <7571@polya.Stanford.EDU> ramsey@polya.Stanford.EDU (Ramsey W. Haddad) writes: >"Convicted Murdered Electrocutes Himself on Prison Toilet" > >I find this very surprising. Do television earphones really put out >enough amps to do this? Amps aren't needed. A fault introducing line voltage to one side of the headset can do you in with milli-amps. If you get it under your skin (or gums) Micro-amps can do it. The safe level of leakage current from modern equipment is considered to be only 3.5 milli-amps. -- Howard.Steel@Waterloo.NCR.COM :-( I Think, Therefore I AM, aka: Howard "The Duck" Steel :-) I think
logajan@ns.UUCP (John Logajan) (03/11/89)
Ramsey W. Haddad writes: > "Convicted Murdered Electrocutes Himself on Prison Toilet" > Do television earphones really put out enough amps to do this? In the good old days, the AC input power was isolated from the internal workings of the TV by a (expensive) transformer. Hence it was much harder to get electrocuted by touching any of the internal stuff even if you had bare feet on a wet concrete floor. Now a days, they have removed the xformer for cost reasons, but they hope that the insulation of the case will keep fingers off "hot" parts. Some TV plugs may have polarized prongs, but I don't think that is a requirement. I had to buy an isolation xformer so I could fix my Sony TV. The part for the TV cost about $2, while the xformer cost $60, oh well. In any event, the earphone question always bothered me -- as my Sony has two of the little jacks out front for me to use. And I do happen to sit on a carpeted concrete floor. Sure I know the chances are slim, but still. -- - John M. Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428 - - ...rutgers!umn-cs!ns!logajan / logajan@ns.network.com / john@logajan.mn.org -
rzh@lll-lcc.UUCP (Roger Hanscom) (03/11/89)
In <1512@csd4.milw.wisc.edu> neighbor@csd4.milw.wisc.edu (Jeffrey Alan Ding) writes: >moral of the story: Always keep one hand in your pocket when working with > with electricity. That way the current won't pass > through your heart. Maybe!! What if you're standing in puddle of water? roger rzh@lll-lcc.llnl.gov
gordon@prls.UUCP (Gordon Vickers) (03/11/89)
In article <7528@batcomputer.tn.cornell.edu> eacj@tcgould.tn.cornell.edu (Julian Vrieslander) writes: > ->Usually headphone circuits run at low voltage, but there might have been a ->fault causing the signal or ground side of the cable to carry line voltage. ->The current that passes into your body when you get a shock depends on the ->resistance in the path. This situation sounds like a worst case. The victim ->was biting on the cable (pressure + moisture = low resistance between wire and ->body). He was sitting on a metal commode (large contact area on metallic ->surface with a low impedance path to ground). The current path from mouth ->to seat is largely water (low resistance) and goes by his heart. -> ->I'm not too surprised. ->-- ->Julian Vrieslander I agree with everything you say but a couple of things still disturb me. Normally, the audio is coupled from the output stage of the amplifier to the headphone jack with a transformer. Normally when a transformer faults, it is an open on either the prymary or the secondary side. An electrocution would require that the transfromer shorte from primary to secondary. Not unheard of, but very rare I beleive. All this assumes that the TV was an old one, probably having tubes. Newer small TV don't use transformers, and drive the earphones directly from the amplifier final output transistors but the voltage supplied to these is most likely low voltage, lower than the minium of 32 Volts normally required for a lethal jolt. Still not impossible , I agree. Since he bit the wire, he did provide a much lower resistances path than in typical accidents. What I don't understand, is why was he attempting this repair in the bathroom and why did he choose to work naked ? - possible but unlikely source of lethal voltage - unlikely place for a T.V. - unlikely place to repair a T.V. - unlikely form of dress for task I'm surprised anyway. Feeling gabby today; third follow-up to this group today. Gordon Vickers 408/991-5370 (Sunnyvale,Ca); {mips|pyramid|philabs}!prls!gordon Every extinction, whether animal, mineral, or vegetable, hastens our own demise.
rodman@mfci.UUCP (Paul Rodman) (03/11/89)
In article <7571@polya.Stanford.EDU> ramsey@polya.Stanford.EDU (Ramsey W. Haddad) writes: >"Convicted Murdered Electrocutes Himself on Prison Toilet" .... deleted story.... > >I find this very surprising. Do television earphones really put out >enough amps to do this? > I would think it might be possible, as I recall through-the-heart current is what kills, with small currents not a problem , and large currents also not a problem as they clench up the heart. (Of course burns and bashed limbs aren't much fun.) I think at about 200ma the heart is made to fibrillate. In this chaotic state you in big trouble until someone can zap you with enough current to clench the heart and start it again. This would be useful knowledge to have straight, anyone out there more in the know on electrocution dangers? Paul K. Rodman rodman@mfci.uucp __... ...__ _.. . _._ ._ .____ __.. ._
john@stiatl.UUCP (John DeArmond) (03/11/89)
> >>"Convicted Murdered Electrocutes Himself on Prison Toilet" > >.... deleted story.... >> >>I find this very surprising. Do television earphones really put out >>enough amps to do this? >> > How in the world did this subject generate so much verbage? The electrocution mechanism is fairly obvious to anyone who knows anything about TV. Most TVs, especially cheap TVs are line operated; ie, they don't have transformers and instead run directly from the line voltage. This means the circuit board and chassis of the TV has the potential to be directly connected to the line. Most TVs have 2 prong polarized plugs which is a weak attempt to keep the chassis cold. It is quite likely that in prison, polarized plugs may be wired wrong and/or cheap, ad-hoc extension cords are un use. The net effect was that when this guy bit through the headphone cord, he was directly connected to the line. John -- John De Armond, WD4OQC | Manual? ... What manual ?!? Sales Technologies, Inc. Atlanta, GA | This is Unix, My son, You ...!gatech!stiatl!john | just GOTTA Know!!!
sic@ritcsh.UUCP (Eric A. Neulight) (03/12/89)
In article <19861@prls.UUCP> gordon@prls.UUCP (Gordon Vickers) writes: > What I don't understand, is why was he attempting this repair in the > bathroom and why did he choose to work naked ? > - possible but unlikely source of lethal voltage > - unlikely place for a T.V. > - unlikely place to repair a T.V. > - unlikely form of dress for task > I guess were really straying from the subject, and from the subject of this newsgroup, so this'll be short ... This prisoner was apparently a convicted murderer who barely escaped the electric chair -- so they weren't keeping him at the country club. This guy was probably being kept in a maximum security cell, and they don't get a bathroom with doors to walk into down the hall. This guy gets a toilet and a sink right next to his bed (no doors). Quite a hotel, huh. Prison can be pretty dehumanizing. But then I just learned all this from the movies. ============================================================================== CLAIMER: Well -- I wrote it! Eric Alan Neulight "Nothing is Impossible -- Just Impractical." Electrical Engineering "For every Lock, there is a Key." Computer Science House "INSANITY is just a state of mine." Rochester Institute of Technology BITNET: EAN4762@RITVAX UUCP: ...!rutgers!rochester!rit!ritcsh!sic ==============================================================================
hgw@julia.math.ucla.edu (Harold Wong) (03/12/89)
In article <1512@csd4.milw.wisc.edu> neighbor@csd4.milw.wisc.edu (Jeffrey Alan Ding) writes: >moral of the story: Always keep one hand in your pocket when working with > with electricity. That way the current won't pass > through your heart. > >neighbor@csd4.milw.wisc. In this case, keep your butt away from the toilet. ------------------------------------------------------------------------------- Harold Wong (213) 825-9040 UCLA-Mathnet; 3915F MSA; 405 Hilgard Ave.; Los Angeles, CA 90024-1555 ARPA: hgw@math.ucla.edu BITNET: hgw%math.ucla.edu@INTERBIT
kluksdah@enuxha.eas.asu.edu (Norman C. Kluksdahl) (03/15/89)
In article <7528@batcomputer.tn.cornell.edu>, eacj@batcomputer.tn.cornell.edu (Julian Vrieslander) writes: > In article <7571@polya.Stanford.EDU> ramsey@polya.Stanford.EDU (Ramsey W. Haddad) writes: > > ``A convicted murderer who had avoided the electric chair was > >electrocuted by accident white sitting naked on a steel toilet in his > >cell, officials said. > Aha!!! You forgot the obvious!!! A distant, crazed relative of the victim managed to get himself a job as a prison guard, then sneaked in some tools when all the inmates were out in the exercise yard, opened the TV set, connected the output of the stepup transformer to the earphone jack (which conveniently disabled sound and ensured that the inmate in question would bite into the headphone wire to try to 'fix' the problem), put contact cement on the metal commode (ensuring that the inmate would be seated on the conductor for the above operation), closed up the TV, and left. After the death of the inmate, he sneaked back into the cell and removed his modifications so as to destroy the evidence. (Shades of "Mission Impossible" ) :-) :-) :-) :-) :-) :-) :-) :-) :-) ********************************************************************** Norman Kluksdahl Arizona State University ..ncar!noao!asuvax!enuxha!kluksdah standard disclaimer implied Useful criticism always appreciated. Senseless flames always discarded.
hgw@julia.math.ucla.edu (Harold Wong) (03/15/89)
I'm going to turn to another subject but almost in the same line of discussion.
I have a line tester consisting of a screwdriver (the probe) connected to a
neon bulb connected to a metal cap on the end which I'm suppose to touch.
If the screwdriver comes
in contact with a hot wire the neon will glow. How does this work? I must be
"ground". I obviously have a different potential than the hot wire but how?
I don't understand this. Can someone define "ground"? Will the difference in
potential eventually equal and the neon stop glowing? Do I recharge myself by
making static? Since I am insulated (shoes, rug, etc) from earth ground am I
a floating ground? What does this all mean?
-------------------------------------------------------------------------------
Harold Wong (213) 825-9040
UCLA-Mathnet; 3915F MSA; 405 Hilgard Ave.; Los Angeles, CA 90024-1555
ARPA: hgw@math.ucla.edu BITNET: hgw%math.ucla.edu@INTERBITsparks@corpane.UUCP (John Sparks) (03/21/89)
<19861@prls.UUCP> In article <19861@prls.UUCP>, gordon@prls.UUCP (Gordon Vickers) writes: > Normally, the audio is coupled from the output stage of the amplifier > to the headphone jack with a transformer. Normally when a transformer > faults, it is an open on either the prymary or the secondary side. An > electrocution would require that the transfromer shorte from primary > to secondary. Not unheard of, but very rare I beleive. Unless a transformer is wound with the primary and secondary on separate posts of the same core, it is just as easy for a short to occur between the primary and secondary as it is between each side alone. On most transformers the primary and secondary are wound together on the same core post. So the wires are lying side by side, a simple scratch could short them together. Also on most older TV's all circuits reference the same ground, that includes one side of the AC line which is usually connected to the metal chassis. The manufacturers used polarized plugs to make sure that the AC neutral wire was the one use for reference. If the prison's outlet was wired backwards, or the polarized plug was replaced with a non-polarized plug and was plugged in backwards, the metal chassis and all of the d.c. circuits would have been referenced from 120VAC, since they shared the same ground. If the transformer output was grounded on one side, or if it used a transistor output, the electrocution would have been possible. I got a nasty shock once while working on an old TV that didn't have a polarized plug. I plugged it in and picked up the metal chassis, intending to flip it over. BBBBZZZAPPP!! It was a shocking experience to say the least (pun intended!). And don't make fun of my last name :-) ---- John Sparks | {rutgers|uunet}!ukma!corpane!sparks | D.I.S.K. 24hrs 1200bps ______________| sparks@corpane.UUCP | 502/968-5401 thru -5406 186,000 miles per second: it's not just a good idea, it's the law.