The apprentice with a question about the physics or characteristics of electricity

[JONATHAN20]

Now im going to assume that everyone here has been juiced with 120 before. Comes with the territory i guess. Now imagine this scenario you working on a plug and you forget its live and grab it. Bang. Sh**. Same situation lets say you put one finger on the brass screw and one finger on the silver screw. again you'll get a buzz. Nothing fatal nothing agonizing.(theres no reason you would ever do this but im just speaking hypath.) Now lets say your in your standard residential panel and you put 1 finger on one of the hot lugs and one finger on the nuetral lug(again not that i would ever attempt) would you get the same wack that you would from a plug doing the same thing? Im assuming so right? Sorry if its a stupid question just something that poppin into my head at work today?

[peter d]

Now imagine this scenario you working on a plug and you forget its live and grab it.

You mean working on a receptacle? ;)

[JONATHAN20]

yes a receptacle funny man

[realolman]

It might be a little less at the receptacle because of the conductor's resistance..

You'll have to let me know, because I ain't tryin' it.

[peter d]

yes a receptacle funny man

Not trying to be funny, but as an apprentice you should learn the correct terminology and not just trade slang.

[JONATHAN20]

i do know all the proper terminology there just no need to be so formal all the time its kinda like saying breaker instead of overcurrent protection. anyways.

[peter d]

i do know all the proper terminology there just no need to be so formal all the time its kinda like saying breaker instead of overcurrent protection. anyways.

Actually here on the forum most of us use formal terminology. It's a lot less confusing that way.

Even something simple like saying "breaker" is not as cut and dry as you think. Many times in commercial and industrial work fuse protection is involved, so to just say "breaker" rather than OCPD would be incorrect in those situations.

[Rewire]

Now im going to assume that everyone here has been juiced with 120 before. Comes with the territory i guess. Now imagine this scenario you working on a plug and you forget its live and grab it. Bang. Sh**. Same situation lets say you put one finger on the brass screw and one finger on the silver screw. again you'll get a buzz. Nothing fatal nothing agonizing.(theres no reason you would ever do this but im just speaking hypath.) Now lets say your in your standard residential panel and you put 1 finger on one of the hot lugs and one finger on the nuetral lug(again not that i would ever attempt) would you get the same wack that you would from a plug doing the same thing? Im assuming so right? Sorry if its a stupid question just something that poppin into my head at work today?
Short answer ,yes

[nafis]

you mean receptacl out let

[electricalperson]

Now im going to assume that everyone here has been juiced with 120 before. Comes with the territory i guess. Now imagine this scenario you working on a plug and you forget its live and grab it. Bang. Sh**. Same situation lets say you put one finger on the brass screw and one finger on the silver screw. again you'll get a buzz. Nothing fatal nothing agonizing.(theres no reason you would ever do this but im just speaking hypath.) Now lets say your in your standard residential panel and you put 1 finger on one of the hot lugs and one finger on the nuetral lug(again not that i would ever attempt) would you get the same wack that you would from a plug doing the same thing? Im assuming so right? Sorry if its a stupid question just something that poppin into my head at work today?
i know a guy that tested a panel with his fingers to see if it was missing a phase. guess thats the old fashioned way of testing voltage before they invented meters :-?

[charlie b]

I knew an old Navy man who said he used to test fuses with his fingers. But he also said that, as a safety precaution, he used the backs of his fingers. He reasoned that if the fuse was bad, and therefore had 120 volts across it, the electrical kick going through his fingers would cause them to curl up, which would pull them away from the source. I hoped he was kidding, but I am not certain.

[charlie b]

First, in answer to your specific question, I believe you would not be able to distinguish the feeling of a shock that came from touching a receptacle's connections and the feeling of a shock that came from touching the bus bars in the panel. True, there would be some amount of voltage drop along the branch circuit, perhaps even as much as 5%. So instead of a 120 volt shock, you might only get a 114 volt shock. I repeat, you would not be able to discern the difference.

Secondly, and most importantly, I disagree absolutely with your presumption that your scenarios do not risk a fatal shock. You can, indeed, without question, be killed by contact with an energized receptacle. If you have been nailed, and have lived to tell the tale, consider yourself lucky. But do you know what lucky circumstances had to exist, for the shock not to have been fatal?

[iwire]

Adding to Charlie's point.

Nothing fatal nothing agonizing


Jonathan, what voltage do you think kills the most people here in the USA?

[growler]

Jonathan, what voltage do you think kills the most people here in the USA?


You do mean in every state except Texas don't you.:D

[electricalperson]

johnathan dont ever think for one second that 120 volts cant kill you. why do you think there are so many codes for residential? take a look at the history behind the codes of GFCI's. buy the book overcurrents and undercurrents to find out. most of the gfci codes were put in because people were killed.

[Strahan]

Now im going to assume that everyone here has been juiced with 120 before. Comes with the territory i guess. Now imagine this scenario you working on a plug and you forget its live and grab it. Bang. Sh**. Same situation lets say you put one finger on the brass screw and one finger on the silver screw. again you'll get a buzz. Nothing fatal nothing agonizing.(theres no reason you would ever do this but im just speaking hypath.) Now lets say your in your standard residential panel and you put 1 finger on one of the hot lugs and one finger on the nuetral lug(again not that i would ever attempt) would you get the same wack that you would from a plug doing the same thing? Im assuming so right? Sorry if its a stupid question just something that poppin into my head at work today?

First thing you need to realize is that 120vac can and will kill under the right circumstances. 6ma of current is enough to send you to another life lots of serious effects before it reaches that point. With 120vac it doesn't take much to cause 6ma to flow. EC&M had a very good article on the myth of 120vac not being harmful about 1 year ago I'll try and find it.

[steelersman]

you mean receptacl out let
no he meant receptacle outlet. If you're going to try to correct someone then at least learn how to spell!!

[steelersman]

First thing you need to realize is that 120vac can and will kill under the right circumstances. 6ma of current is enough to send you to another life lots of serious effects before it reaches that point. With 120vac it doesn't take much to cause 6ma to flow. EC&M had a very good article on the myth of 120vac not being harmful about 1 year ago I'll try and find it.
But that current would need to travel accross your body not just between 2 fingers on the same hand.

[iwire]

But that current would need to travel accross your body not just between 2 fingers on the same hand.

So if your going to run electricity across two fingers make sure your floating in the air.

[ce2two]

remember u only die once ,now try that on 100 volts dc ,it doesn"t want to let go of u ......feels like a 277volt shock ??//////// it hurts?

[LarryFine]

First, in answer to your specific question, I believe you would not be able to distinguish the feeling of a shock that came from touching a receptacle's connections and the feeling of a shock that came from touching the bus bars in the panel. True, there would be some amount of voltage drop along the branch circuit, perhaps even as much as 5%. So instead of a 120 volt shock, you might only get a 114 volt shock. I repeat, you would not be able to discern the difference.
I don't believe the voltage drop would even be detectable with a human shock.

That's why my answer is, with the same contact, the same shock would result.

[electricalperson]

remember u only die once ,now try that on 100 volts dc ,it doesn"t want to let go of u ......feels like a 277volt shock ??//////// it hurts?
i think ac is more dangerous than DC. if you multiply 120 by 1.414 you get 169 volts. so that 120 volt ac shock is like getting shocked by 169 volts instead. if DC is more dangerous why is it not used in electric chairs?

[mkgrady]

i think ac is more dangerous than DC. if you multiply 120 by 1.414 you get 169 volts. so that 120 volt ac shock is like getting shocked by 169 volts instead. if DC is more dangerous why is it not used in electric chairs?

A/C is convenient. It's already there. To use DC would require additional equipment

[electricalperson]

A/C is convenient. It's already there. To use DC would require additional equipment
if we used DC we would need a lot more power plants or dc generators at the basement. AC is better since it can be transformed to higher voltages and sent long distances and all that good stuff but its also more dangerous

[ceb58]

Sorry if its a stupid question just something that poppin into my head at work today?

Not a stupid question, but you should really concentrate on work. Unless you are trying to come up with ways to amuse your self on the weekends:D

[djcrzysounds@yahoo.com]

ATTENTION ATTENTION.... I'm still an apprentice too, but the occasional whack from 120V, sometimes 240V and the odd 277V whack I got was enough to remind me to respect my occupation. However, I somehow always knew not to touch the bus bar inside a panelboard. I know the current could be higher then that of a receptacle. But I can honestly say I have never gotten whacked while working in a live panel(can someone loan me a piece of wood to knock on)

[frizbeedog]

ATTENTION ATTENTION.... I'm still an apprentice too, but the occasional whack from 120V, sometimes 240V and the odd 277V whack I got was enough to remind me to respect my occupation.

Let's turn off some circuits before we knock ourselves sensless.

Try some LOTO.

:smile:

[TOOL_5150]

I know the current could be higher then that of a receptacle.

The current is the same. You would allready be dead by the time a 20A breaker tripped because you got between the phase and ground.

Yes, you can pull more current through a 100A main breaker vs. a 20A branch, but for the topic we are discussing, that point is moot.

In conclusion, yes, you can be killed from touching a 120v receptacle.


~Matt

[TOOL_5150]

Let's turn off some circuits before we knock ourselves sensless.

Try some LOTO.

:smile:


Thank you for taking care of that statement!

LOTO could very well save your life. :cool:

~Matt

[djcrzysounds@yahoo.com]

Let's turn off some circuits before we knock ourselves sensless.

Try some LOTO.

:smile:
I do now... lessons learned are a beautiful thing, however when doing the occasional residential device replacement and commercial troubleshooting, I have been known to leave the circuit on.

[bjp_ne_elec]

What I didn't see anyone even feedback or consider was even if it's your fingers reaching across the terminals of a receptacle, it also might have to do with if you've set up another ground path through your body. If your finger first touches the hot leg, before the second finger hit the neutral or ground, and you were grounded - say as you were either on a wet concrete floor or leaning up against a metal radiator - that current could pass through your body.

[iaov]

Always, always remember. This stuff can kill you. Someone is killed by 120 vts. every day in the USA. There are old electricians and there are bold electricians. There are no old bold electricians!!

[charlie b]

. . . (can someone loan me a piece of wood to knock on)
I usually use my forehead for that purpose.

[charlie b]

Let us please understand the nature of the danger here!But that current would need to travel accross your body not just between 2 fingers on the same hand. If your finger first touches the hot leg, before the second finger hit the neutral or ground, and you were grounded - say as you were either on a wet concrete floor or leaning up against a metal radiator - that current could pass through your body.
Bob said it correctly: So if you’re going to run electricity across two fingers make sure your floating in the air.
Keep in mind that current takes every available path, not just the shortest one (as in from finger to finger), and not just the path of least resistance. If your body is not “floating in the air,” as Bob put it, and if you touch a hot wire with one hand and the neutral wire with another part of the same hand, then in addition to current flowing through your hand, it will flow through your body to the floor below you, and from their into the building’s foundation, and through dirt to the ground rod, and up the GEC to the N-G bond point within the service panel. It may be a high resistance path, and the current flowing in that path might be small, but it takes only a small current to kill a person.

[weressl]

First, in answer to your specific question, I believe you would not be able to distinguish the feeling of a shock that came from touching a receptacle's connections and the feeling of a shock that came from touching the bus bars in the panel. True, there would be some amount of voltage drop along the branch circuit, perhaps even as much as 5%. So instead of a 120 volt shock, you might only get a 114 volt shock. I repeat, you would not be able to discern the difference.

Secondly, and most importantly, I disagree absolutely with your presumption that your scenarios do not risk a fatal shock. You can, indeed, without question, be killed by contact with an energized receptacle. If you have been nailed, and have lived to tell the tale, consider yourself lucky. But do you know what lucky circumstances had to exist, for the shock not to have been fatal?

The voltage difference would be even more insignificant. The voltage drop only exist under load. If the human body is the only load/resistance in the completed circuit then the actual load current of 10-100mA would hardly produce any voltage drop.

Resistance path would of course vary greatly.

Finger to finger to bonded casing.
Hand to hand to bonded casing.
Hand to feet to ground.

[weressl]

So if your going to run electricity across two fingers make sure your floating in the air.

Well the folks here been arguing that the earth has SUCH great resistance going back to the neutral bonding place to complete the circuit that it wouldn't matter.

Now all of a sudden it matters?

Can't have it both ways..........:smile:

[charlie b]

Well the folks here been arguing that the earth has SUCH great resistance going back to the neutral bonding place to complete the circuit that it wouldn't matter.
I trust that you aren't going along with them, that you aren't buying that argument? :wink:

[iwire]

Well the folks here been arguing that the earth has SUCH great resistance going back to the neutral bonding place to complete the circuit that it wouldn't matter.

Now all of a sudden it matters?

Can't have it both ways..........:smile:

Gee I thought you where knowledgeable enough to know that the earth provides enough of a fault path to kill but still not enough to trip over current devices under 600 volts.

I will try to take it down a notch so even you to will be able to comprehend. :D

[weressl]

Gee I thought you where knowledgeable enough to know that the earth provides enough of a fault path to kill but still not enough to trip over current devices under 600 volts.

I will try to take it down a notch so even you to will be able to comprehend. :D

Nobody EVER proposed that there will be sufficient current to trip the OCP via earth alone. Based on the picture provided on the MH website to 'splain earth resistance's efect of voltage gradiation produce such high resistance that a source 50' away would not kill people in most cases. Interestingly resistances of varying length and distance always talkked about Ohm/foot, but I have never seen such associated with earth resistance in these aruments. Nevermind contact surface area which also a variable.

Follow-up question; will a GFCI trip is there is a human contact between the phase and the ground to a source 50' away?

Yeah, if you will take it down a notch even you may be able to comprehend your own words...8-)

[Rewire]

First, in answer to your specific question, I believe you would not be able to distinguish the feeling of a shock that came from touching a receptacle's connections and the feeling of a shock that came from touching the bus bars in the panel. True, there would be some amount of voltage drop along the branch circuit, perhaps even as much as 5%. So instead of a 120 volt shock, you might only get a 114 volt shock. I repeat, you would not be able to discern the difference.

Secondly, and most importantly, I disagree absolutely with your presumption that your scenarios do not risk a fatal shock. You can, indeed, without question, be killed by contact with an energized receptacle. If you have been nailed, and have lived to tell the tale, consider yourself lucky. But do you know what lucky circumstances had to exist, for the shock not to have been fatal?
its not the volts its the amps

[steelersman]

Always, always remember. This stuff can kill you. Someone is killed by 120 vts. every day in the USA. There are old electricians and there are bold electricians. There are no old bold electricians!!
If what some people have said about old guys that they used to know using their fingers to test panels and circuits and the like then that statement is wrong! :)

[steelersman]

its not the volts its the amps
wow that is (no offense intended) got to be one of the most ignorant replies to a post I've read since I've been here I think. It has nothing to do with what he wa saying and I would venture to say that 99% of the members here already know that.

[Rewire]

wow that is (no offense intended) got to be one of the most ignorant replies to a post I've read since I've been here I think. It has nothing to do with what he wa saying and I would venture to say that 99% of the members here already know that.
nothing like being "politely"told you are ignorant but you have only been here a short while and have not yet learned to use PMs to question someones intelligence I will let it pass,what I was pointing out was for the OP not for the oldtimers on the board and it was that "shock" is a product of amperage so saying 112V shock or 120V shock may confuse some who are not versed in electrical theory

[fireryan]

i think what the op is asking is what circumstances would need to be present to get killed from touching a 120v receptacle. I think

[MAK]

wow that is (no offense intended) got to be one of the most ignorant replies to a post I've read since I've been here I think.
I believe the term is ignant.:grin:

[steelersman]

nothing like being "politely"told you are ignorant but you have only been here a short while and have not yet learned to use PMs to question someones intelligence I will let it pass,what I was pointing out was for the OP not for the oldtimers on the board and it was that "shock" is a product of amperage so saying 112V shock or 120V shock may confuse some who are not versed in electrical theory
So if you were addressing the OP then perhaps you should have quoted his OP instead of Charlie's. And I've been using PM quite a bit FYI. :)

[LarryFine]

wow that is (no offense intended) got to be one of the most ignorant replies to a post I've read since I've been here I think.Gee, how could anybody find that comment offensive? :roll:

[fireryan]

im with you larry:wink: Is there something im missin:confused:

[adamants]

the only safe voltage is 0volts

[weressl]

Gee, how could anybody find that comment offensive? :roll:

Knowing what the word actually means helps to decide:

ig·no·rant http://www.merriam-webster.com/images/audio.gif (javascript:popWin('/cgi-bin/audio.pl?ignora05.wav=ignorant')) Pronunciation: \ˈig-n(ə-)rənt\ Function: adjective Date: 14th century 1 a: destitute of knowledge or education <an ignorant society> ; also : lacking knowledge or comprehension of the thing specified <parents ignorant of modern mathematics> b: resulting from or showing lack of knowledge or intelligence <ignorant errors>

So while we commonly interpret 'ignorant' as 'stupid', it merely reflects on plainly lacking knowledge of the subject.

I take issue with the 'most ignorant', as there are numerous posts have been posted with far more lack of knowledge than the one in question.:D

I think the OP's use of language and expression did not help though, however the substance was interesting and it showed that the 'apprentice' is really trying to understand. He was thinking and his thgoughts had merit showing a progress of deepening understanding of the subject. Not unlike Einstein who did not come to the theory of relativity in HS, bot had taken a lot of thinking until he got there.

[Rewire]

So if you were addressing the OP then perhaps you should have quoted his OP instead of Charlie's. And I've been using PM quite a bit FYI. :)
perhaps you should have put some thought into the tone of your post ,this is a very polite board and I have noticed that I seldom see someone being caracterized as "ignorant" in what the post I know that name calling and mud slinnging our common place on many boards but this board has always held to a higher standard by the very people who choose to be a part of it that is one of the reasons I enjoy it as much as I do

[iwire]

perhaps you should have put some thought into the tone of your post ,this is a very polite board

Well said.

[steelersman]

perhaps you should have put some thought into the tone of your post ,this is a very polite board and I have noticed that I seldom see someone being caracterized as "ignorant" in what the post I know that name calling and mud slinnging our common place on many boards but this board has always held to a higher standard by the very people who choose to be a part of it that is one of the reasons I enjoy it as much as I do
That doesn't change the fact that you didn't address the OP but instead chose to address Charlie's statement instead making your post seem quite pointless. Sorry but I'm just calling it like I see it.

[roger]

That doesn't change the fact that you didn't address the OP but instead chose to address Charlie's statement instead making your post seem quite pointless. I think you're the only one that seems to have a problem with Rewire and Charlie's conversation.

Sorry but I'm just calling it like I see it.

So you have been here a couple of months now and you have never seen a thread where two, three, four, or more individuals will enter into a discussion that drifts away from the OP?

You better hang on to your hat because not only does it happen, it happens on a regular basis.

Roger

[MF Dagger]

You better hang on to your hat because not only does it happen, it happens on a regular basis.


Wanna go ride bikes?

[roger]

Wanna go ride bikes?

Depends, what kind of bike do you have?

Roger

[steelersman]

I think you're the only one that seems to have a problem with Rewire and Charlie's conversation.



So you have been here a couple of months now and you have never seen a thread where two, three, four, or more individuals will enter into a discussion that drifts away from the OP?

You better hang on to your hat because not only does it happen, it happens on a regular basis.

Roger
I know that they often drift off topic and I have no problem with that at all, as I have often been part of that myself. But if you're going to reply to something then just reply to the right quote.

[roger]

What makes you think he wasn't replying to the right quote? He quoted Charlie and replied to it.

Roger

[steelersman]

ok fair enough.

[fireryan]

maybe we should quit arguing and get beack to the topic. what are the circumstances that could cause contact with a 120v receptacle to be fatal? Anyone????????????????????????

[steelersman]

maybe we should quit arguing and get beack to the topic. what are the circumstances that could cause contact with a 120v receptacle to be fatal? Anyone????????????????????????
perhaps your body being wet and having a lower than average resistance.

[roger]

maybe we should quit arguing and get beack to the topic.

Who's arguing?

what are the circumstances that could cause contact with a 120v receptacle to be fatal? Anyone????????????????????????

Hmmm, could possibly be someone working on a live receptacle don't you think?

If you are asking what the numbers would have be, click HERE (http://www.osha.gov/SLTC/etools/construction/electrical_incidents/eleccurrent.html)

Roger

[charlie b]

What are the circumstances that could cause contact with a 120v receptacle to be fatal?
Ohm’s Law is all you need. Depending on a person’s physical state (e.g., age, gender, height, weight, percent body fat) and whether they are tired and sweaty at the time of the contact, their body resistance (taken from their hand, in contact with the receptacle, to their foot, in contact with the floor) could be as low as 250 ohms. Add another 50 ohms for the floor and the dirt that is in the path between the person’s foot and the building’s service ground rod, you get 300 ohms. Divide 120 volts by 300 ohms, and you get 0.4 amps. Looking at the link that Roger just provided, we see that that is definitely enough current to kill the person.

Q.E.D.