12-2 NM cable as switch.
- Thread starter masterjohn
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peter d
Senior Member
- Location
- New England
Re: Peter
Re: Peter
If you make accidental contact with either one it will kill or severly injure you if the conditions are right. Either voltage system is perfectly capable of pushing a fatal amount of current through your body.
I certainly hope by stressing one over the other you are not luring people into a false sense of security when working on 120/208 volt systems.
Re: Peter
Gmack said:
If you make accidental contact with either one it will kill or severly injure you if the conditions are right. Either voltage system is perfectly capable of pushing a fatal amount of current through your body.
I certainly hope by stressing one over the other you are not luring people into a false sense of security when working on 120/208 volt systems.
peter d
Senior Member
- Location
- New England
Re: Peter
Re: Peter
No matter what notion you have on voltage levels, it will always be the current that kills you.
I've been using the GFCI example. It will trip above a 5 milliamp leakage. Anything above 5 milliamps is dangerous and potentially fatal. Notice the GFCI doesn't have anything to do with sensing voltage but CURRENT.
Also notice that such a small amount of current is deadly.
Re: Peter
Gmack said:
No matter what notion you have on voltage levels, it will always be the current that kills you.
I've been using the GFCI example. It will trip above a 5 milliamp leakage. Anything above 5 milliamps is dangerous and potentially fatal. Notice the GFCI doesn't have anything to do with sensing voltage but CURRENT.
Also notice that such a small amount of current is deadly.
Peter
Peter
Peter, it would be safer to point out that higher voltages are far more dangerous and do far greater damage to the body once electrocution has occurred.
Case in point, last months maybe two/ EC mag/ECM. A worker got shocked while working on a 277v switch. It knocked him out and after the emergency room let him return home. He died ten days later of internal burns that were undetectable at the ER. No heart stoppage. JFYI.
Peter
Peter, it would be safer to point out that higher voltages are far more dangerous and do far greater damage to the body once electrocution has occurred.
Case in point, last months maybe two/ EC mag/ECM. A worker got shocked while working on a 277v switch. It knocked him out and after the emergency room let him return home. He died ten days later of internal burns that were undetectable at the ER. No heart stoppage. JFYI.
peter d
Senior Member
- Location
- New England
Re: Peter
Re: Peter
I agree. Read my earlier posts again, and you will see that I've been saying that higher voltage has the potential to push a lot of current through the body all along. This is basic ohms law we are talking about. When we complete a circuit, the voltage source will "push" the current through the circuit. If that happens to be a human body, it will get cooked. You don't disagree with that , do you?
Re: Peter
Gmack said:
I agree. Read my earlier posts again, and you will see that I've been saying that higher voltage has the potential to push a lot of current through the body all along. This is basic ohms law we are talking about. When we complete a circuit, the voltage source will "push" the current through the circuit. If that happens to be a human body, it will get cooked. You don't disagree with that , do you?
Gmack, here is the info from OSHA that may help you understand fatal current values.
http://www.osha.gov/SLTC/etools/construction/electrical_incidents/eleccurrent.html
Notice, fatal current can flow at very low voltages given the right conditions which could lower the bodies resistance.
It is basic ohms law.
Roger
http://www.osha.gov/SLTC/etools/construction/electrical_incidents/eleccurrent.html
Notice, fatal current can flow at very low voltages given the right conditions which could lower the bodies resistance.
It is basic ohms law.
Roger
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Gmack,
What general concept do you want to people to remember:
Amps kill regardless of the voltage. Therefore all voltages are unsafe.
or
Low voltage is safer than high voltage.
Can you use your choice to evaulate the relative safety of a circuit where there is a 23V difference between two conductors and current is flowing? Or how about a system that measures 300V between conductors and no current is flowing?
Teaching the correct facts is always better than teaching only half-truths. Half-truths have a habit of causing dangerous generalizations, like "current follows the path of least resistance".
What general concept do you want to people to remember:
Amps kill regardless of the voltage. Therefore all voltages are unsafe.
or
Low voltage is safer than high voltage.
Can you use your choice to evaulate the relative safety of a circuit where there is a 23V difference between two conductors and current is flowing? Or how about a system that measures 300V between conductors and no current is flowing?
Teaching the correct facts is always better than teaching only half-truths. Half-truths have a habit of causing dangerous generalizations, like "current follows the path of least resistance".
Roger / Jim
Roger / Jim
Give me a little time to answer you both.
But let us consider state sponsored electrocutions/executions. I mean all the data we are throwing around here suggest that a 9volt battery could do it. The "art" of electrocution was was done by trial and error.
Today they use 2000v nominal/aprox. Im sure that if they could zap'em with a 9volt and stop the heart, they would save on the electric bill.
Just a thought.
Roger / Jim
Give me a little time to answer you both.
But let us consider state sponsored electrocutions/executions. I mean all the data we are throwing around here suggest that a 9volt battery could do it. The "art" of electrocution was was done by trial and error.
Today they use 2000v nominal/aprox. Im sure that if they could zap'em with a 9volt and stop the heart, they would save on the electric bill.
Just a thought.
chicar
Senior Member
- Location
- Lancaster,Pa
You guys still on this thread? How about this; All of it kills,voltage amps,arcing and heat. So teach our future electricians;
Respect the trade
Bring your workface to work everyday.
The N.E.C.
To go beyond the N.E.C. [marking ungrounded conductors]
and last but not least;
Respect your elders. Stay safe,
Peace
Respect the trade
Bring your workface to work everyday.
The N.E.C.
To go beyond the N.E.C. [marking ungrounded conductors]
and last but not least;
Respect your elders. Stay safe,
Peace
Roger
Roger
I scanned that site. Iam not qualified to know/comment how they calculated their data. Medically.
But in our world I think Iam qualified to know/comment on the hazards of higher voltages in the field.
That site you provided does have a similar component to our world though. It speaks of being "hung up" at lower voltages far under what is common in our field, resulting in death.
However in our world with the "lower" voltages utilized in construction, this "being hung up" doesn't show much effect on heart stoppage.
I think we are talking apples to oranges here. With some cross over.
UNTIL! we start going up the ladder to higher construction voltages. Then much more violent damage occurs to a man with some exceptions.
Remember, at higher "AC/construction voltages terrible things happen to the body/flesh of the person electrocuted, other than a heart stoppage that causes death or severe injury .IMO Starting at 277/480 and up.
Roger
I scanned that site. Iam not qualified to know/comment how they calculated their data. Medically.
But in our world I think Iam qualified to know/comment on the hazards of higher voltages in the field.
That site you provided does have a similar component to our world though. It speaks of being "hung up" at lower voltages far under what is common in our field, resulting in death.
However in our world with the "lower" voltages utilized in construction, this "being hung up" doesn't show much effect on heart stoppage.
I think we are talking apples to oranges here. With some cross over.
UNTIL! we start going up the ladder to higher construction voltages. Then much more violent damage occurs to a man with some exceptions.
Remember, at higher "AC/construction voltages terrible things happen to the body/flesh of the person electrocuted, other than a heart stoppage that causes death or severe injury .IMO Starting at 277/480 and up.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: Roger / Jim
Re: Roger / Jim
And more so if the executions always proceeded as predicted. While all executions I've researched (just now) are successful, success in this context has a pretty wide margin.
I agree with Jim, preaching more respect for high voltage simply opens the door for disrespect and injury from lower voltages.
Re: Roger / Jim
That would be a valid statement, if the voltage for said "appliance" was not always close to 2000V. Source.Gmack said:
And more so if the executions always proceeded as predicted. While all executions I've researched (just now) are successful, success in this context has a pretty wide margin.
I agree with Jim, preaching more respect for high voltage simply opens the door for disrespect and injury from lower voltages.
- Location
- Illinois
- Occupation
- retired electrician
Gmack,
Don
Also remember that for the most part work on energized equipment operating above 50 volts is prohibited.
Don
Jim
Jim
Jim, want I want to convey to apprentices is that starting at 277/480 things get real dangerous.
It is not an amp kills issue from class anymore. With allot of misguided medical data at voltages and currents non consistent with the real world construction/utilized voltages.
Now that shouldn't have to be said by me. It should be taught and reinforced from day one, by any "teacher" raising apprentices. School or in the field.
As you are PE, I am curious that you would ask.
As to your multiple choice question.
The answer is simple. In an electricians world.
Low voltage is safer.
Jim
Jim, want I want to convey to apprentices is that starting at 277/480 things get real dangerous.
It is not an amp kills issue from class anymore. With allot of misguided medical data at voltages and currents non consistent with the real world construction/utilized voltages.
Now that shouldn't have to be said by me. It should be taught and reinforced from day one, by any "teacher" raising apprentices. School or in the field.
As you are PE, I am curious that you would ask.
As to your multiple choice question.
The answer is simple. In an electricians world.
Low voltage is safer.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: Roger
Re: Roger
Consider Ohms law:
E = I x R, solving for amps: I = E / R
Meet Stan.
Stan is about to have a very bad day.
Stan is perfectly dry. His skin's resistance is around 10000 ohms. I have tied him to a chair, and connected a neutral to his big toe. I have connected an ungrounded conductor to his thumb. As I energize the circuit, I look at my calculator...
I = 120V / 10000
I = .012 amps
Stan just had a little episode, but I have paddles. He's feeling better now. I hope he's ready for round two...
I = 277V / 10000
I = .028 amps
Stan just stopped breathing. Fortunately, Stan is a paramedic who was coming home from work when I flagged him down, so I'm able to get him going again. Good thing, because he's gonna play utility guy for a minute. Unfortunately, all this excitements starting him to sweat a bit...
I = 7200V / 5000
I = 1.44 amps
As the voltage goes up, so do the amps. Therefore, higher voltage allows more current to flow through the same resistor. More current kills more effectively. Just ask Stan. 8)
Re: Roger
Where did OSHA draw a voltage distinction in being "hung up" or unable to voluntarily release from the shock? They said that it can even occur at lower voltages, making even lower voltages equally unsafe!Gmack said:
What does this mean? That being unable to let go of a source of shock is unrelated to heart stoppage?
You're right, heart stoppage is an acceptable, insignificant injury. Why have we been wasting so much time GFCI protecting 120V circuits? Whiners. :lol:
Consider Ohms law:
E = I x R, solving for amps: I = E / R
Meet Stan.
Stan is about to have a very bad day.
Stan is perfectly dry. His skin's resistance is around 10000 ohms. I have tied him to a chair, and connected a neutral to his big toe. I have connected an ungrounded conductor to his thumb. As I energize the circuit, I look at my calculator...
I = 120V / 10000
I = .012 amps
Stan just had a little episode, but I have paddles. He's feeling better now. I hope he's ready for round two...
I = 277V / 10000
I = .028 amps
Stan just stopped breathing. Fortunately, Stan is a paramedic who was coming home from work when I flagged him down, so I'm able to get him going again. Good thing, because he's gonna play utility guy for a minute. Unfortunately, all this excitements starting him to sweat a bit...
I = 7200V / 5000
I = 1.44 amps
As the voltage goes up, so do the amps. Therefore, higher voltage allows more current to flow through the same resistor. More current kills more effectively. Just ask Stan. 8)
- Location
- Massachusetts
Re: Jim
Re: Jim
:roll:
Guys its a lost cause gmack knows it all and we are not going to teach him anything. :roll:
Gmack you have no idea the of the collective knowledge here at this forum. :lol:
Re: Jim
Gmack said:
:roll:
Guys its a lost cause gmack knows it all and we are not going to teach him anything. :roll:
Gmack you have no idea the of the collective knowledge here at this forum. :lol:
peter d
Senior Member
- Location
- New England
Re: Jim
Re: Jim
That is really bad instruction. Having some kind of benchmark for the danger point really has no place in the electrical industry. As the OSHA website shows (did you actually look at it?), small amounts of current from low voltage sources can kill. The danger starts long before a 277/480 volt system.
An apprentice could be injured working on a phone system, lured into the false belief that it's safe because it's "low voltage." Trust me, I learned this the hard way once.
Re: Jim
Gmack said:
That is really bad instruction. Having some kind of benchmark for the danger point really has no place in the electrical industry. As the OSHA website shows (did you actually look at it?), small amounts of current from low voltage sources can kill. The danger starts long before a 277/480 volt system.
An apprentice could be injured working on a phone system, lured into the false belief that it's safe because it's "low voltage." Trust me, I learned this the hard way once.
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: Roger
Re: Roger
George, have you been watching Hostel again?
Re: Roger
georgestolz said:
George, have you been watching Hostel again?
peter d
Senior Member
- Location
- New England
Re: George
Re: George
Well, I guess that settles it then. :lol:
Re: George
Gmack said:
Well, I guess that settles it then. :lol:
- Location
- Illinois
- Occupation
- retired electrician
Gmack,
Don
What really needs to be taught is that it is NEVER safe to work on energized equipment and in the rare cases where it is permitted, the proper selection and use of PPE must be taught.
Don
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