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View Full Version : Amps kill you, Volts don't?


tim314
07-13-2004, 03:06 AM
I often hear people say (regarding electrocutions), it's not the volts that kill you, it's the amps. This doesn't really make sense to me. If current and voltage are related by Ohms law ( V = IR ), then shouldn't you automatically end up with more current flowing through you when you're exposed to a larger voltage? (assuming your body provides a constant resistance.) Why would being exposed to high voltage be any less dangerous than being exposed to a large amount of current?

Larry Borgia
07-13-2004, 03:24 AM
If I may venture a WAG:

It's the actual current that flow through you that kills you, not the potential difference. Amps measure the current, volts the potential difference, so that's what gives rise to the saying.

For example, you could move between a pair of capacitors with a large potential difference (measured in Volts) but if you were moving through a non-conducting medium you'd be OK. If the capacitors were dropped in a conducting medium (like a swimming pool) a current would flow (measured in amps) and you would be cooked.

hopefully this will do till someone who really knows what they're talking about comes along.

Ponster
07-13-2004, 03:39 AM
Both amps and volts will kill you if they are large enough.

Considering that the body has a fixed resistance, 40,000 volts at 0.001 amps will not kill you whereas 200 volts at 1 amp will.


This is why, IMHO, we consider amps to be more important than current.


If someone tells you that he was exposed to a live wire and amazingly wasn't harmed you should ask how many amps the wire was carrying and not how many volts.

Small Clanger
07-13-2004, 05:52 AM
In utterly non-technical terms, the voltage is the amount of ooph available. The amount of current that flows depends on the resistance between the points you apply the voltage to. The resistance is simply how hard it is for electricity to get from one point to another.

What kills you (in the usual senario) is the amount of current flowing across your heart, which interferes with the heart's own electrical system which works with relatively tiny currents. If you get a shock between two fingers (don't try this) you'll probably be OK as the current misses your heart. You'll still get burnt fingers. If you get a shock between your hands or between your left hand and feet you are in trouble.

Other things to consider:

If you get a shock from a build up of static electricity the voltage will be pretty high (in the region of 10,000 volts) but it won't kill you* because there isn't enough charge there to generate a decent current.

The source resistance. You could have a whacking great voltage between terminals but it might not be able to supply more than a certain amount of current. The mains supply is not like that. If you jam a crowbar across a mains socket it will try to keep the voltage between the terminals at 230/120 volts (it's AC but that doesn't matter here). Depending on the resistance of your crowbar - which will be very low - the current it will try to supply will be enormous, hundreds of Amps. What happens of course is that a fuse blows (or breaker throws). If you stick your spare crowbar across the fuse then most likely your wiring will catch fire (that's why the fuse is there). In principle the mains has negligible source resistance, that's why it is so dangerous. In practice it's usually limited to 13 Amps, but that is way more than is needed to kill you.

Back to the OP. It is the current that kills you but you need to apply enough Volts to the right place. A car battery can supply hundreds of Amps but at only 12 Volts it can't overcome your (dry) skin's resistance sufficiently to kill you. If you have wet or sweaty hands this may not be the case. I don't recommend experimenting.

*Unless it's lightning. Don't play with lightning.

glee
07-13-2004, 07:04 AM
Other things to consider:

If you get a shock from a build up of static electricity the voltage will be pretty high (in the region of 10,000 volts) but it won't kill you* because there isn't enough charge there to generate a decent current.


*Unless it's lightning. Don't play with lightning.

When I was a pupil, we played around with a Van der Graaf generator (holding hands to form a chain to the metal doorknob, so the next person entering would get a shock - and so would we all).
I understand this is a lot of (static electricity) volts, but it just made our hair stand on end.

Is that correct?

Small Clanger
07-13-2004, 07:19 AM
glee, have a look here Van der Graaf generators (http://amasci.com/emotor/vdg.html) Goto the safety page for reassurance (and warnings).

Apparently a human chain is not such a good idea, with enough people charged to a high voltage you can store a heck of a lot of energy. And it all gets discharged though the last sap in the chain. From one hand to the other (v.bad see previous post or read the link). You really don't want your heart in the circuit.

Crafter_Man
07-13-2004, 09:03 AM
I often hear people say (regarding electrocutions), it's not the volts that kill you, it's the amps. This doesn't really make sense to me.When it comes right down to it, there needs to be a certain amount of current that flows through you in order for you to be electrocuted. In other words, the relationship between “getting zapped” and “electricity” is primarily defined in terms of current, not voltage. Anything over 0.01 A is “risky territory.”

So let’s say you’re grounded and you touch a live wire. Or you touch both terminals of a battery. Or whatever. So how much current is flowing through you?

1. If the power source approximates an ideal voltage source, then the current following through your body is IB = VS/ RB, where VS is the voltage of the ideal voltage source, and RB is your body resistance.

2. If the power source approximates an ideal current source, then the current following through your body is IB = IS, where IS is the ideal current source.

3. If the power source is modeled as an ideal voltage source in series with a resistor (“source resistance”), then the current following through your body is IB = VS/( RS + RB), where VS is the ideal voltage source, RS is the source resistance, and RB is your body resistance.

4. If the power source is modeled as an ideal current source in parallel with a resistor (“source resistance”), then the current following through your body is IB = (IS RS)/( RS + RB), where IS is the ideal current source, RS is the source resistance, and RB is your body resistance.


If current and voltage are related by Ohms law ( V = IR ), then shouldn't you automatically end up with more current flowing through you when you're exposed to a larger voltage? (assuming your body provides a constant resistance.)Yes. But you should also realize that the voltage across your body depends on more than just the voltage of the voltage source. It also depends on the source resistance and your body resistance. The source resistance and your body resistance act as a “voltage divider.” At any rate, the “severity” of the electrocution is primarily defined in terms of current, not voltage. See my previous comments on how to calculate the current.

Crafter_Man
07-13-2004, 09:14 AM
whereas 200 volts at 1 amp will [kill you].As long as the power source can source at least 0.1 A, the maximum current capability does not matter. As an example, a car battery is capable of sourcing 500 A. But this does not matter, since it can only source this much current into a very low resistance load.

If someone tells you that he was exposed to a live wire and amazingly wasn't harmed you should ask how many amps the wire was carrying and not how many volts.This is incorrect. Again, as long as the power source can source at least 0.1 A, the maximum current capability does not matter. A 240 V / 200 A circuit is no more lethal than a 240 V / 1 A circuit. A 120 VAC outlet is no more lethal that the “hot” service wire going into your house from the pole. A car battery that can produce 500 A is no more lethal than two 6V lantern batteries in series.

If someone tells you that he was exposed to a live wire and amazingly wasn't harmed, you should ask him the following: A) Was he grounded? B) What was the voltage?

MMI
07-13-2004, 09:49 AM
My recollection (from my double E for dummies course (okay, Electrical Engineering for non Electrical Engineers)) is that "lethal" amperage is about .1 amps. Less is annoying to damaging and more may have nasty to very nasty effects, but may not kill you.

The human body has a variable, not a fixed resistance. Dry you probably have a resistance of 5000 ohms. Wet, about 1000 ohms. So:

water + you + 110 volt source = death (110V/1000 ohms = .11 amps)

Without water, the amperage is just .022 amps, so pain, damage, but not necessarily fatal. Crank the voltage to 500 and you are back to .1 amps. Wear some mack-diggety insulation (rubber sneakers need not apply) and you can probably shift the voltage required by quite a lot.

Trigonal Planar
07-13-2004, 10:13 AM
My one EE prof used to say "its not volts or amps that kills you - its resistance".

glee
07-13-2004, 10:34 AM
glee, have a look here Van der Graaf generators (http://amasci.com/emotor/vdg.html) Goto the safety page for reassurance (and warnings).

Apparently a human chain is not such a good idea, with enough people charged to a high voltage you can store a heck of a lot of energy. And it all gets discharged though the last sap in the chain. From one hand to the other (v.bad see previous post or read the link). You really don't want your heart in the circuit.

Ta for that.
My school science teachers were not very hot on safety...

KP
07-13-2004, 10:57 AM
It's not just science teachers. This was a very common demonstration in science museums for many decades. At the Boston Museum of Scicnce, they used to do this every hour or two with groups ranging from a dozen to almost a hundred. AFAIK, there was never a serious injury. The practice didn't even end when they moved their biggest Van De Graf generator (20-30ft tall) into a specially constructed "Theater of Electricity" to allow higher voltage exhibitions (with Faraday cages protecting the operator and audience). They still periodically set up smaller Van de Graffs (typically 5-6 ft tall) as standing displays and did this demonstration. As far as I know they still haul out the "mini" (3 ft tall, under 100 kV) for school field trips and the school vacation crowds. I don't know if the still shock schoolkids en masse today, but they were still doing it 10-15 years ago.

(But of course, it takes a lot more to shock kids these days)

Loopydude
07-13-2004, 11:12 AM
I agree with the "it's the resistance that kills you" to a point. Unfortunately, our bodies use changing electrostatic potentials across cell membranes as a means of sending signals and regulating critical biomechanical processes. This is no more true than in the heart, the proper electrophysiologial function of which is critical to life. So it's not necessary to fry the individual to kill them; in fact you don't even have to burn them, just have sufficient current flow through the heart, and you be dead. That critical level isn't all that high, so if you're really unlucky, even modest current applied to the right place can cause fibrulation and, subsequently, death.

It's also possible to burn body parts clean off and not even lose consciousness, depending on where and how the current is applied.

My brother, who is an electrician, witnessed this latter unfortunate scenerio first-hand (not him, a co-worker). I won't go into the gory details, but lets just say I don't fool around with much wiring these days after hearing that story.

Crafter_Man
07-13-2004, 11:34 AM
water + you + 110 volt source = death (110V/1000 ohms = .11 amps)It’s actually worse than that, since instantaneous currents are lethal. In your example, the body would see instantaneous current magnitudes of 0.156 amps.

FlippyFly
07-13-2004, 11:49 AM
My understanding is as follows:

The combination of the voltage and the resistance determine whether or not you get a shock. At a high voltage (>500 Volts) you, as a person, will probably get a shock under normal cercumstances.

Once you get a shock, it's the current that matters. A small current is no problem (like a static spark) and a big current is a real problem (like an electric chair).

So basically, the voltage is either a yes or a no. Do you get shocked? Yes or no. Then, you look at the severity of the shock.

Low voltage will stop you from getting shocked in the first place, low current will minimize the damage if you do get shocked.

High voltage will cause you to take a shock, high current will kill you.

tim314
07-13-2004, 02:20 PM
My one EE prof used to say "its not volts or amps that kills you - its resistance".
If we want to be even more precise, it's really the lack of resistance that kills you, right? If your body had very high resistance, than having a certain potential difference placed across you would only generate a little current. But if your resistance is lower, the current produced by that potential difference is much greater.

The opposite of resistance is conductance, is that right? (I used to know these things, but it's been a while.) So I guess it's really the conductance that kills you?

Q.E.D.
07-13-2004, 02:39 PM
The opposite of resistance is conductance, is that right?
We say the inverse, not the opposite. But yes, it's conductabnce. The unit of conductance was once the mho (ohm spelled backwards--EEs have a sense of humor), but these days, you're more likely to hear seimens. Both represent the same quantity.

Chronos
07-13-2004, 02:49 PM
Considering that the body has a fixed resistance, 40,000 volts at 0.001 amps will not kill you whereas 200 volts at 1 amp will.This statement is nonsensical. In order to get 40,000 volts at 0.001 amps the body would have to have a resistance of 40 megaohms, but to get 200 volts at 1 amp, the body would need to have a resistance of only 200 ohms. Forty million is not equal to 200, so this is inconsistent with "Considering that the body has a fixed resistance".

And the skin's resistance can vary, but current through or voltage across the skin is not going to kill you (unless you manage to burn the skin entirely off). What matters is generally the heart, which does have a fairly constant resistance (it's always wet). So an increase in current through the heart is directly related to an increase in voltage across the heart. You cannot have a high voltage across the heart but a low current through it, nor vice versa, so it is meaningless to say that it's the current or the voltage that kills you. To say that it's not the volts that kill you, it's the amps is analogous to saying that it's not the milage that puts wear on your car, it's how far you drive.

The other main way to get killed by electricity, other than by throwing off the heart's pacemaker, is for the electricity to cook you. Here, it would be accurate to say that it's the watts (power) which kill you. Power can be expressed by the equations P = VI, P = V2/R, or P = I2R. So, if exposed to a constant voltage source, a low resistance element will cook faster than a high resistance element, but if exposed to a constant current source, a high resistance element will cook faster than a low resistance element. Practically, constant voltage sources are more common than constant current sources, so a lower resistance element would be at greater risk. So it would probably be more accurate to say that conductance kills, rather than resistance kills.

FlippyFly
07-13-2004, 03:17 PM
Well I am pretty confused now. Lets put it as simply as possible.

I have an electric chair, and I flip the switch but OOPS, the guy is still alive (I am NOT trying to start a debate about capital punishment. Go to IMHO for that). What do I need to do?

1 - increase the voltage
2 - increase the current
3 - doesn't matter (but they are different things)
4 - doesn't matter (they are dependant, increasing one will increase the other)

Goosemaster
07-13-2004, 03:58 PM
Well I am pretty confused now. Lets put it as simply as possible.

I have an electric chair, and I flip the switch but OOPS, the guy is still alive (I am NOT trying to start a debate about capital punishment. Go to IMHO for that). What do I need to do?

1 - increase the voltage
2 - increase the current
3 - doesn't matter (but they are different things)
4 - doesn't matter (they are dependant, increasing one will increase the other)


To my understanding, voltage is the propensity for electricity to want to travel and current is the quantity of the flow.

If you wanted to kill someone using "the chair," voltage would not be the key factor. High Voltage requirements are circumvented by using a wet sponge, specifically a sponge moistened with undestilled water, applied to the poor bastard's head in between hte skin and the elctrode. As many of the geniuses explained in massive detail, this circumvents the protective and resistance of human skin. Basically, the water creates a "path through iron gates," reducing the importance of having an energy delivery system that is high in voltage.

The current aspect of the delivery system is more relevant however in such a situation. The higher the current, the more energy going into the "system, or in this case, the axe murderer. You want as much energy flowing depending on the task. As people stated, if you want to distrupt his heart, the amount of amerpage isn't that high since it does not have to make its way through the skin. Then again, if you want to cook him ala 'green mile' use all the current you can pump out.

Keep in mind I am an EE student and I used to have a nasty habit of falling asleep in my Circuits class ;) so I might be totally RIGHT, or not...:D





Or you could just through a bucket of water at the guy.....make sure it isn;t a metal pail and that you are wearing gloves though, Mr. executioner ;)

engineer_comp_geek
07-13-2004, 04:26 PM
Well I am pretty confused now. Lets put it as simply as possible.

I have an electric chair, and I flip the switch but OOPS, the guy is still alive (I am NOT trying to start a debate about capital punishment. Go to IMHO for that). What do I need to do?

1 - increase the voltage
2 - increase the current
3 - doesn't matter (but they are different things)
4 - doesn't matter (they are dependant, increasing one will increase the other)

Electricity kills you in basically two ways. First of all, it can interrupt your heart's normal way of doing things. Once you get your heartbeat screwed up, it doesn't tend to fix itself, and eventually you die from lack of blood flow. However, this isn't how an electric chair kills you. An electric chair uses the second method, where basically it cooks you to death. The theory is that there's enough damage done to your brain in the first jolt that you don't feel the rest, otherwise it would be a fairly gruesome way to die (which is the stuff for a different forum, or at least a different thread).

Directly relevant to this thread, what you need to do is basically increase the cooking power of your chair. The first thing you would want to do is make sure that your chair has good connections everywhere. A bad connection won't allow as much current to pass through it. A bad connection will result from things like corroded copper in one of the wires or connections, or a dried out or synthetic sponge where the connection to the body is made. A wire that is too thin would also count as a bad connection, since it will lose all of the power in heating up the wire and not enough current will get transferred to the victim. All of this is number 2 on your list, increasing the current, but we're not changing the voltage yet.

The next thing to do would be to change the voltage (number 1 on your list). If we increase the voltage, all other things being equal, the current will also increase.

Note here that we're kinda focusing on the current delivered into the load, so that's why electricians have the saying "its the volts that jolts but the mills that kills" (meaning milliamps, or current). But really it's the power transferred to the load that matters (power is voltage multiplied by current, for those of you that slept through your circuits classes ;) ). By focusing on the current delivered to the load, you focus on the actual power being delivered, not the power lost through bad connections, thin wire, etc.

We're kinda focusing on an electric chair here, but the principle is the same for other things as well. There are many things besides the source voltage that determine how much current actually flows. It's not the source voltage that gets you. It's how much actual current you get to flow, which translates into how much power is actually delivered to the load, that causes the real damage.

Ezstrete
07-13-2004, 05:42 PM
Electricity kills you in basically two ways. First of all, it can interrupt your heart's normal way of doing things. Once you get your heartbeat screwed up, it doesn't tend to fix itself, and eventually you die from lack of blood flow. However, this isn't how an electric chair kills you. An electric chair uses the second method, where basically it cooks you to death. The theory is that there's enough damage done to your brain in the first jolt that you don't feel the rest, otherwise it would be a fairly gruesome way to die (which is the stuff for a different forum, or at least a different thread).

Directly relevant to this thread, what you need to do is basically increase the cooking power of your chair. The first thing you would want to do is make sure that your chair has good connections everywhere. A bad connection won't allow as much current to pass through it. A bad connection will result from things like corroded copper in one of the wires or connections, or a dried out or synthetic sponge where the connection to the body is made. A wire that is too thin would also count as a bad connection, since it will lose all of the power in heating up the wire and not enough current will get transferred to the victim. All of this is number 2 on your list, increasing the current, but we're not changing the voltage yet.

The next thing to do would be to change the voltage (number 1 on your list). If we increase the voltage, all other things being equal, the current will also increase.

Note here that we're kinda focusing on the current delivered into the load, so that's why electricians have the saying "its the volts that jolts but the mills that kills" (meaning milliamps, or current). But really it's the power transferred to the load that matters (power is voltage multiplied by current, for those of you that slept through your circuits classes ;) ). By focusing on the current delivered to the load, you focus on the actual power being delivered, not the power lost through bad connections, thin wire, etc.

We're kinda focusing on an electric chair here, but the principle is the same for other things as well. There are many things besides the source voltage that determine how much current actually flows. It's not the source voltage that gets you. It's how much actual current you get to flow, which translates into how much power is actually delivered to the load, that causes the real damage.

Aw come on guys!

Amps? Volts, Resistance?

How about simple power?

Power is watts--- resistance times applied voltage.

The proper combination of your resistance and an applied voltage and you've had it.

That's why,sometimes, the results are horrific-----the body resistance is an unknown------------------the voltage applied is an over voltage--result is a smoky mess.

PHEW

Rick
07-13-2004, 06:26 PM
Something that is being overlooked here, is where the voltage is being applied, and where the ground point is. For example on one model car I used to work on when I would lean in to adjust the fuel injection, my elbow would be gounded, and my forearm would somtimes brush the low tension terminal of the ignition coil. (about 100-300V A/C) This would make me jump, but put me in no danger as the current path went from forearm to elbow.
If I am dinking with the park plug wires I might get a 35,000 Volt shock, but again since my arm was grounded, the only damage was from my elbow hitting something sharp at Mach 4 as I flinched.
The worst shock I ever got, should have killed me. I was very very lucky. I was changing a 110V socket behind my stove. I had the stove pulled out and was standing behind it, leaning back against it. (ground). Now usually when I do this work, I work hot (power on), but this time, my wife ragged on me, so I turned off the breaker. Since I knew the power was off (BAD assumption) I did not hesitate to grab the wire. Hot was dead, no problem. The neutral was shared with another circuit that was still hot. When I grabed the one neutral wire, the current went up along my arm, across my back and out through the stove. :eek: I danced the funky chicken for a few seconds, before I broke the connection. I think what saved me was the fact that it was a very hot day, and I was sweating buckets. I believe that the current traveled along my moist skin, and to ground. some current still traveled through me, since I could feel the shock, but I think my sweat acted as a voltage divider, and saved my ass.
yes I was a :wally for not knowing about shared neutrals.

Crafter_Man
07-13-2004, 07:19 PM
Tim314: 1st paragraph is correct.

Chronos: 100% correct.

Flippyfly: If the power source can be approximated as an ideal voltage source (which is likely), then increasing the voltage will make the chair more effective.

Goosemaster: Sorry, but your entire post is incorrect. EE student? Better hit the books! ;) (I’m just jabbing ya. I was once an EE student…)

Ezstrete: Power is not “resistance times applied voltage.” It is V2/R.

Rick: The neutral must have been broken, since you cannot get a jolt from a neutral that is tied to ground at the breaker box.


I don’t mean to toot my horn here, but everything you need to know can be found in my first post.

engineer_comp_geek
07-13-2004, 09:26 PM
How about simple power?


You apparently didn't read the last two paragraphs of what you quoted.


Power is watts--- resistance times applied voltage.


Erm, current times voltage, not resistance times voltage. Or, current squared times resistance, or voltage squared divided by resistance. Take your pick.

Rick
07-14-2004, 01:31 AM
Rick: The neutral must have been broken, since you cannot get a jolt from a neutral that is tied to ground at the breaker box.
2 neutral wires one back to the box, one that ran up to the light fixture. The light was on when I started and boy did I light up when I touched that wire. :eek:

casdave
07-14-2004, 06:10 AM
Although we tend to look at current, and sometimes power, when the heart is affected it can be useful to look at the amount of energy delivered at a certain rate. This can allow for more accurate dispensing of energy.

When you watch almost any hospital show on tv, such as ER, one very common scenario is that of a patient having a cardiac arrest and perhaps needing defibrillation.

The device used to carry out this task is moreorless a large charge storage device, and a means of delivery which can be controlled.

You often hear mention of the amount of energy to be delivered, in Joules.

The number of Joules per second is Watts, however the energy on defib machines is delivered in periods much shorter than one second and the machine is fully discharged.

Averaged out over a period of time, the number of Watts may appear to be less.

In such a case the amount of current delivered is misleading, a large current delivered over a very short timespan can stop the heart, but delivered over a longer period will cook internal organs.

Similarly, a large amount of energy delivered over a very long period of time may well not even be noticeable.

Crafter_Man
07-14-2004, 09:09 AM
2 neutral wires one back to the box, one that ran up to the light fixture. The light was on when I started and boy did I light up when I touched that wire. :eek:Yep, and this is what I meant by a “broken neutral.”

As you learned, you can get zapped by a neutral if the conditions are “right.” The conditions are as follows:

1. The neutral must be going directly to a load (lamp, appliance, whatever).
2. The other side of the load must be hot. (This also means that, if the load is controlled by an external wall switch, the switch must also be “on.”)
3. The load must be “on.”
4. The neutral cannot be connected at the breaker box. This is what I mean by a “broken neutral.”
5. You are grounded.

If all five of these conditions are met, you can get zapped by touching the neutral.

Ezstrete
07-14-2004, 11:17 AM
[QUOTE=Crafter_Man]Tim314: 1st paragraph is correct.

Chronos: 100% correct.

Flippyfly: If the power source can be approximated as an ideal voltage source (which is likely), then increasing the voltage will make the chair more effective.

Goosemaster: Sorry, but your entire post is incorrect. EE student? Better hit the books! ;) (I’m just jabbing ya. I was once an EE student…)

Ezstrete: Power is not “resistance times applied voltage.” It is V2/R.

Rick: The neutral must have been broken, since you cannot get a jolt from a neutral that is tied to ground at the breaker box.

Nitpicking is another form of avoidance.

"Them what can't "is fated to become editors-or horn blowers.

Amps-volts----without them in combinatiion that chair would just be another park bench.

That's WATT I said.

More power to all!

EZ


I don’t mean to toot my horn here, but everything you need to know can be found in my first post.[/QUO

beltbuckle
07-14-2004, 11:30 AM
I once took a shock using worm prods - long electrodes with a wooden handle on top you plug in to a 110v AC source and stick into the ground because it irritates the worms and they come up to the top of the earth for harvesting. We used to sell worms.

I was a kid and these things are inherently dangerous. I was moving one around in the ground and my hand slipped off the handle on to the electrode. I attempted to pull it off with my other hand, but then my other hand became paralyzed from the current as well. There I sat, concious but paralyzed, for about 10 seconds, when my grandpa noticed me from the window inside the house. He ran outside and knocked me off the worm prod and unplugged them.

So I took the brunt of a 110 V/ 20 A circuit for about 15 seconds, all the way through my body (except my head), as the current went in through my arms and out through my feet into the ground. And I took no real damage, just a bit shaken up after it all. The current must have traveled lose to my skin and avoided my heart.

Small Clanger
07-14-2004, 12:02 PM
If we're gonna hijack this thread with my shocking electric shock experience stories. Here's mine.

I was 16 or so playing guitar in my room, electric guitar. Guitar in right hand (earthed strings good solid contact there). Go to pick up switched on amplifier with left hand. No back on amplifier - index finger contacts with live terminal in the power switch.

240 Volts across the chest.

I was thrown across the room by the shock but was unfortunately still connected to the National Grid. I couldn't shout for help as my voice didn't work, paralysed I supposed. I remember thinking "I-am-going-to-die" My legs did work and I managed to kick the amp away. I don't really know how long I was wired up for, probably a few seconds.

I should have died. I was in shock (natch) for the rest of the day and had chest pains for weeks, it felt like my lungs had come loose. I still have a scar on my index finger where the switch terminals burned into it.
I stuck to the accoustic for a while after that.

Needless to say I am now always extremely flipping careful when dealing with mains voltages.

Crafter_Man
07-14-2004, 12:33 PM
Ezstrete: Huh?

Beltbuckle: Were the electrodes connected to an isolation transformer? If not, they should have been. It is still possible to get zapped with isolation transformer, but it does offer more protection.

beltbuckle
07-14-2004, 12:52 PM
Beltbuckle: Were the electrodes connected to an isolation transformer? If not, they should have been. It is still possible to get zapped with isolation transformer, but it does offer more protection.[/QUOTE]

No, of course not. These worm prods were built by my grandpa and just hardwired to the outlet, no switch or transformer. We wouldn't want to make them safer, now would we?

casdave
07-14-2004, 12:57 PM
Small Clanger

Its pretty common for musos to unhook the mains earth from their amplifiers and other mains driven stuff as it usuallly kills hum loops. Some of this stuff is classed as double insulated and allegedly does not need and earth wire, however, the secondary insulation on electrical musical merchandise is often little more than a compressed cardboard cover over the mains transformer and of course it all helps keep costs down.

The risks are obvious but your amp should have blown the fuse when the insulation broke down. I wonder if your amp had been prviously owned or it it had been modified ?

Its also why power breakers(Residual current devices) are 'A Very Good Thing'

Small Clanger
07-14-2004, 01:07 PM
I wonder if your amp had been prviously owned or it it had been modified ?modified in that the back cover had been removed. There was no insulation over the mains switch terminals where my hand went.

Its also why power breakers(Residual current devices) are 'A Very Good Thing'Yup. I later life I ran a PA company that started out doing rock band gigs. All our gear was on RCDs and we supplied RCD equipped muti-socket boards for the bands' backline. I wasn't gonna see anyone fried on my watch.

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