Electricity is dangerous

[dleccord 5,000+ posts]

Electricity is dangerous because of its disruptive effect on the life support organs of the human body. We characterize electricity by two quantities: voltage and current. Voltage is measured in units called volts and current is measured in units of amps. The primary factors determining the effect of electricity on the body are the amount and path of the current passing through the body.

Currents of less than 0.02 amp may produce sensations ranging from tingling to sharp pain. A more serious effect occurs if the current causes muscles to contract. A person touching a live wire with their outstretched hand may literally not be able to let go of the wire due to the current's effect on the muscles. Experienced electricians who must sometimes deal with wires which may be live always use the backs of their hands to move the wires; if a current were present, the contacting muscles would cause the hand to pull away from the wire. Currents from 0.03 to 0.07 amp will begin to impair the ability of the person to breathe.

The most dangerous range of currents is from 0.1 to about 0.2 amp. Currents in this range can cause death by initiating fibrillation (uncontrollable twitching) of the heart, which stops the regular flow of blood to the rest of the body. Currents much larger than 0.1 amp do NOT result in fibrillation and instead stop the heart completely. If the duration of the current is short, the heart will usually start to beat by itself after the current is removed.

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[silvercookie 5,000+ posts]

ok?

 

[dleccord 5,000+ posts]

 

[rusty_armadillo 10+ year member]

I'm not reading that. Is there anything important in there or just common knowledge?

 

[SmokeyDog 10+ year member]

Electricity is dangerous because of its disruptive effect on the life support organs of the human body. We characterize electricity by two quantities: voltage and current. Voltage is measured in units called volts and current is measured in units of amps. The primary factors determining the effect of electricity on the body are the amount and path of the current passing through the body.
Currents of less than 0.02 amp may produce sensations ranging from tingling to sharp pain. A more serious effect occurs if the current causes muscles to contract. A person touching a live wire with their outstretched hand may literally not be able to let go of the wire due to the current's effect on the muscles. Experienced electricians who must sometimes deal with wires which may be live always use the backs of their hands to move the wires; if a current were present, the contacting muscles would cause the hand to pull away from the wire. Currents from 0.03 to 0.07 amp will begin to impair the ability of the person to breathe.

The most dangerous range of currents is from 0.1 to about 0.2 amp. Currents in this range can cause death by initiating fibrillation (uncontrollable twitching) of the heart, which stops the regular flow of blood to the rest of the body. Currents much larger than 0.1 amp do NOT result in fibrillation and instead stop the heart completely. If the duration of the current is short, the heart will usually start to beat by itself after the current is removed.

thats why they make gfci or gfi and arc fault breakers witch trip if and teeth wet hands water etc touches the wire. and does so before .o3amps. arc faults are now code in mass for all bedroom plugs there are other new safty neasures in place but i havent wired anything ac in years . remeber that volts dont kill amps do. and you have to be gounded to be zaped. if you jump grab a wire and not be touching the ground nothing happens. there are ways you can be in a puddle grabing a live wire and not get shocked. electricidy will always find the path of less resitions to the ground or earth

 

[tdg 10+ year member]

Cliff notes: electricity can kill. Leave the angry electrons inside the insulation.

 

[JimJ 5,000+ posts]

One hand rule.

Dead solder slingers tell no tales...

 

[DBfan187 5,000+ posts]

all are common sense

 

[Johnny Law.Lulz 5,000+ posts]

Still cool knowledge, we all knew that basic principle but the sepcifics are nice to know i guess.

 

[NoCoSPL 10+ year member]

A GFCI trips at .005 amps. Thats milli amps. A GFCI looks for a differece between the current between the hot and the neutral. 10 amps in and 10 amps out no trip. But as soon as it sees a differerence from input and the return current path in .005 amps or more you trip. Also Arc Fault circuit breakers don't protect people from shock, they prevent arcs within the receptacle. I have a chart for amperage flow in one of my books on how much it takes to stop your heart and how much it takes to cook your arm from the inside out like a microwave.

 

[MakeshiftAudio 10+ year member]

*Sigh.*

Is it sad, that from all of the electrical work I do, I see different numbers every single time from different people?

Voltage plays a large factor, and determines how much current will flow through a given resistance(such as the resistive value from arm to arm, arm to leg, etc etc).

Take something fairly common like neon sign transformers, which commonly operate from 4kV to 15kV from a current rating of 5mA to 60mA and some even 120mA. Generally, within the HV community the 12/60 (12kV 60mA) is considered a lethal combination, given that the arc burns through the skin, which is a large contributing factor of overall resistance.

You get the point, and you can use ohms law to calculate current flow: I=E/R

Though, when using AC, it would be safe to apply the peak voltage, so multiply the RMS value by 1.414 to get the peak. 170V for 120VAC RMS, and 340V for 240VAC RMS. So on and so forth.

Electricity is generally dangerous, but if you use the one hand rule as well as a jesus/chicken stick (essentially an insulating rod, made out of plastics etc) you're at least safer than you were. Many things can still go wrong, such as moisture+dust collecting on things, possibly creating a conductive path. HV is a scary world, then you mix radio frequency work into it making it a weird scary world.

The body resistance is fairly low, and cannot be measured while the person is living due to the heart and the neurological system interfering with the measurements.

 

[NoCoSPL 10+ year member]

*Sigh.*
Is it sad, that from all of the electrical work I do, I see different numbers every single time from different people?

Voltage plays a large factor, and determines how much current will flow through a given resistance(such as the resistive value from arm to arm, arm to leg, etc etc).

Take something fairly common like neon sign transformers, which commonly operate from 4kV to 15kV from a current rating of 5mA to 60mA and some even 120mA. Generally, within the HV community the 12/60 (12kV 60mA) is considered a lethal combination, given that the arc burns through the skin, which is a large contributing factor of overall resistance.

You get the point, and you can use ohms law to calculate current flow: I=E/R

Though, when using AC, it would be safe to apply the peak voltage, so multiply the RMS value by 1.414 to get the peak. 170V for 120VAC RMS, and 340V for 240VAC RMS. So on and so forth.

Electricity is generally dangerous, but if you use the one hand rule as well as a jesus/chicken stick (essentially an insulating rod, made out of plastics etc) you're at least safer than you were. Many things can still go wrong, such as moisture+dust collecting on things, possibly creating a conductive path. HV is a scary world, then you mix radio frequency work into it making it a weird scary world.

The body resistance is fairly low, and cannot be measured while the person is living due to the heart and the neurological system interfering with the measurements.

Body's resistance is fairly high. Until you break the skin, than low resistance in your blood

 

[Rich B 5,000+ posts]

 

[MakeshiftAudio 10+ year member]

Body's resistance is fairly high. Until you break the skin, than low resistance in your blood

Well, high and low is from a perspective.

To me, anything under 10k in this application is low. What is high to you? If you are going to blatantly oppose my statement, back it up.

You can not measure resistance of a living body, basing on how a multimeter/etc measures resistance. I have read(from other sources) numbers from 1.5kohms-30kohm depending on probe placement and surface area of contact. Specifically arm to chest measurements when grabbing a conductor. Any of those numbers do not work well when applying I=E/R.

 

[JimJ 5,000+ posts]

HV is a scary world, then you mix radio frequency work into it making it a weird scary world.

Scariest thing I've worked on is the 3.5kV B+ in the RF deck of an amplifier...any time you have a safety interlock on the cabinet, you know something's fun inside //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

I got bit by the 500V plate voltage in my monoblocks once, that's all it took to respect the power supply caps //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif That bleeder resistor isn't there for looks, lol.

 

[JuicyJeff 10+ year member]

Lol shocked myself on my computer power supply lol. 16 Amps. I was plugging it in and had the cap off and my hamd hit the circuit board and man did I get woken up haha

 

[MakeshiftAudio 10+ year member]

Reminds me of the time my tank capacitor bleed resistor lead came off. It's not that I got bit by it, but rather the "Crap..." moment when I noticed it after charging. Something like .1uF@22kV. 242J of pulse rated goodness. Had to get out the 10Mohm-resistor-on-a-stick.

What you got shocked by in the computer power supply was probably the doubled rectified mains, or mains itself. Highly unlikely you got shocked by the LV output. Lol.