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In Reply to: RE: That's the, aptly named, death cap. Nt posted by John Elison on October 30, 2016 at 06:11:59
It will pass a maximum of only 2.26-mA of current and that assumes it's in series with a direct short.We are not talking about a dead short here. We are taking about the voltage drop across the human body. If the human body, say from one hand to the other hand, is placed in series with a .05mfd capacitor and connected to a 120Vac source are you then saying only a maximum of 2.26ma of current will pass through the body?
I have shot trouble on bad circuits where a loose or corroded connection adds a high resistance in series with the connected load. In such a case where the voltage is, for example, 120Vac when measured at the load may be zero or may read a few volts or more than a few volts. Open/disconnect the Hot Line from the load and the Hot Line to neutral Line will measure the full 120Vac nominal voltage. If a person accidently puts their body across the bad loose and or corroded circuit, hot and neutral or earth ground, will they receive an electrical shock? Most likely....
Would you be willing to place your body in series with an old 1940s-1960s .05mfd paper condenser connected to a 120Vac source to prove your theory?
Best regards,
Jim
Edits: 10/30/16 10/30/16Follow Ups:
> We are not talking about a dead short here. We are taking about the voltage drop across the human body.
Okay! However, the human body has resistance so I was modeling the human body as a dead short with zero resistance for maximum current from 120-volt source. If your body has 50k-ohms resistance, the current through your body would be 1.65-mA with a voltage drop of 82.3-volts. If your body has 500k-ohms resistance, the current would 0.239-mA with a voltage drop of 28.6-volts.
> Would you be willing to place your body in series with an old 1940s-1960s .05mfd paper condenser connected to a 120Vac source to prove your theory?
Well, I don't have one of those old capacitors and I can't imagine why anyone would use one in that application. However, I just tried touching a modern 0.05-uF capacitor connected to my line voltage and I definitely could feel the shock. I used two fingers on one hand rather than both hands because I didn't want the current going through my heart. My finger tips tingled. It felt kind of like touching a little 9-volt battery to my tongue. Have you ever tried that. I didn't want to hold on to it very long, but it didn't hurt me.
A serious situation could occur if the capacitor became shorted. Then it would provide a direct low resistance path for current as if it were a wire instead of a capacitor. However, as long as the capacitor remains in good shape, there should not be a problem.
Best regards,
John Elison
A serious situation could occur if the capacitor became shorted. Then it would provide a direct low resistance path for current as if it were a wire instead of a capacitor. However, as long as the capacitor remains in good shape, there should not be a problem.
That's exactly the problem John. Most of the people who will encounter the death cap are users of vintage equipment that may be over 50 years old so I wouldn't take for granted the capacitor is in good shape. The "death cap" was a staple of audio design before people started getting serious about electrical safety and insisted on the use of double-insulated chassis with polarized plugs on components without a safety ground. I don't know if anyone has been killed by it yet, but I've heard stories of getting shocked.
Okay! However, the human body has resistance so I was modeling the human body as a dead short with zero resistance for maximum current from 120-volt source. If your body has 50k-ohms resistance, the current through your body would be 1.65-mA with a voltage drop of 82.3-volts. If your body has 500k-ohms resistance, the current would 0.239-mA with a voltage drop of 28.6-volts.
Quote:
The NIOSH states "Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms. Wet or broken skin may drop the body's resistance to 1,000 Ohms," adding that "high-voltage electrical energy quickly breaks down human skin, reducing the human body's resistance to 500 Ohms."
https://en.wikipedia.org/wiki/Electric_shock
Well, I don't have one of those old capacitors and I can't imagine why anyone would use one in that application. However, I just tried touching a modern 0.05-uF capacitor connected to my line voltage and I definitely could feel the shock. I used two fingers on one hand rather than both hands because I didn't want the current going through my heart. My finger tips tingled. It felt kind of like touching a little 9-volt battery to my tongue. Have you ever tried that. I didn't want to hold on to it very long, but it didn't hurt me.
John,
The old paper condenser was the capacitor that was used in the old guitar amps from the 1940s, 1950s, and probably the early 1960s. Not sure about the 1960s though.
However, I just tried touching a modern 0.05-uF capacitor connected to my line voltage and I definitely could feel the shock.
I used two fingers on one hand rather than both hands because I didn't want the current going through my heart.
If you are willing to try the test again, using your two fingers, first wet your fingers with your mouth and do the test again. Report back your findings.
Jim
Edits: 10/30/16
If wetting your fingers reduces resistance, then the maximum current flow can be no greater than 2.26-mA with a 120-volt, 60-Hz source. The shock will be noticeable, but it won't kill you. I'll let you conduct the test this time. Let us know how it feels.
Good luck,
John Elison
I'll let you conduct the test this time. Let us know how it feels.
LOL, I'm not going to do it.
I been shocked enough accidently over my lifetime without deliberately subjecting myself to it. LOL......
I do know wetting your fingers will increase the experience more. When ringing out a phone line you can hold the tip of the receiver in one hand and run the index finger of the other hand down the terminals of the 66 block. When you hit the pair you are looking for you will hear the sound of the tone generator. Sometimes if the air is dry and the skin of the finger is dry you wet the tip of the finger before running it down the 66 block. It works a lot better for finding the toner signal if the signal is weak on the pair you are looking for. The only downside is if you run your wet finger across the terminals on the 66 block of a live phone line that is ringing, it will bite you hard. Sometimes you might feel a slight shock with a dry finger. You definitely will feel it with a wet fingertip.
Best regards,
Jim
Edits: 10/30/16 10/30/16
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