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

[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

 

[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.

~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.

 

[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.

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...

 

[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