[Besoeker]

Do you? All I've seen you do this entire thread is try to make everybody think you're smart and to attack Rancid. Neither of which have anything to do with the topic.

Really???

Let me remind you of what he accused me of:

You're a fairly new member to pofo. Some advice; being combative and being a general dick

I have not once responded in kind. Not once.

So try to work out who is attacking whom here before you make such invalid accusations.

[Besoeker]

So which is more deadly? Unlimited Volta or unlimited Ampere?

As it happens, there is a similar discussion going on in an electrical forum on whether it is the current or voltage that is lethal.
The simple fact is that you can't divorce one from the other. Anything above 0.1A can be lethal. But without enough voltage being present to make that current flow it doesn't matter how much current is available.

A 12V car battery is an example of a unit that may supply 1,000 Amps but the 12 Volts isn't anywhere nearly enough to deliver that fatal current. By way of comparison, the electric chair was around 2,000V.

[Rancid]

A 12V car battery is an example of a unit that may supply 1,000 Amps but the 12 Volts isn't anywhere nearly enough to deliver that fatal current. By way of comparison, the electric chair was around 2,000V.

I'm going to guess you don't really understand the other basic electronics formula of Q = CV.......

Short answer:

A relatively high and sustainable current flow, would imply that the necessary "high" voltage and charge capacity is present.


Long Answer:

A 12V car battery could theoretically deliver 1000Amps if the resistance is small enough. The question then becomes, how long could it sustain such a high current. With current technology, it wouldn't be long. Again, to my original point, voltage doesn't matter unless there's a large charge capacity behind it. That is, Q = CV. The C needs to be big enough for the V to become sustainable enough to generate and sustain a significant current (and thus be potentially lethal). Though, in terms of potential to kill, it all depends on where that current actually flows too (like I originally said). It's going to be near impossible to kill someone by touching a 12V battery against their external skin, since that's generally higher resistance, and the flow of current would likely not go through a sensitive organ, like the heart. However, a 12V car battery could possibly kill you if you can directly connect it to your heart, where the resistance will be MUCH smaller, and you can be sure the current will flow through the heart. It's the same reason why a 1000V - 5000V static discharge from when your rub your socks on a rug doesn't kill. Again, it all depends on the what and where..

Still, the point stands. It's much more about current than voltage. Yes, voltage and current are related (duh), but the point is, the voltage and the capacity of the charge behind it has to be significant enough to generate and sustain the current flow. This is why I say, at the end, it's about "high" current. Though, perhaps I should amend that to say "high" and sustainable current.

A relatively high and sustainable current flow, would imply that the necessary "high" voltage and charge capacity is present. Hence, I can easily justify that it's all about current. Current is really a catch-all term here. Get it now?

However, this isn't really the point of the thread. Can we get off this now, or do you want to keep looking like a fool? I'm sure that any further discussion, will just take this in circles since you clearly don't entirely understand voltage/current/capacitance.

[Besoeker]

A 12V car battery is an example of a unit that may supply 1,000 Amps but the 12 Volts isn't anywhere nearly enough to deliver that fatal current. By way of comparison, the electric chair was around 2,000V.

I'm going to guess you don't really understand the other basic electronics formula of Q = CV.......

You guess incorrectly. Give it up.

[Rancid]

Ok, I will give it up.

You are right in all your glory and wisdom.

[Besoeker]

A 12V car battery could theoretically deliver 1000Amps if the resistance is small enough. The question then becomes, how long could it sustain such a high current.

No it doesn't. You quite simply wrong about that. It's a total irrelevance.

Again, to my original point, voltage doesn't matter unless there's a large charge capacity behind it.

Wrong on that one too. The voltage does matter. That's why a 12V battery, no matter how big, is unlkely to be lethal unless you short it out and set fire to yourself. But that's not electrocution.

That is, Q = CV. The C needs to be big enough for the V to become sustainable enough to generate and sustain a significant current

I have designed a lot of stuff in my career. Some of that was high current rectifier systems designed to produce up to 70,000A continuously. 24/7. Mostly these were low voltage hexaphase* systems for anodising plants. Usually these have been in the 30-40V range. No risk of fatal electrocution from that.

*Diagram for a hexaphase system:



And one water cooled limb:



Ready to give it up yet?

[Rancid]

A lot of engineers and people that have worked around electricity are often not very knowledgeable in the very area they work in. Just saying "I've done XXXX" doesn't always translate to deep understanding.

Anyway, my point was, that although voltage is a factor, in the end, it's about current.

I found this presentation:
http://www.publicpower.org/files/PDFs/M ... odyrev.pdf

These guys are saying that it's more about current than anything else. They list the primary factors as amount of current, where the current flows, and the time the current flows. All their charts are listed in terms of current too.

I think you need to email those guys and tell them how irresponsible they are for spreading such misinformation.


In practical terms, you're going to need some higher voltage, yes, since electrocution will likely happen from skin contact. Sure, but still, the current flow, location, of the flow, and time will determine the severity of the injury. You cannot pinpoint a voltage value that would kill, you can do that with current.

[Besoeker]

A lot of engineers and people that have worked around electricity are often not very knowledgeable in the very area they work in. Just saying "I've done XXXX" doesn't always translate to deep understanding.

To actually be qualified as a professional engineer, you need to have a pretty good understanding of the physics and the mathematics. At least in this country you do.

Anyway, my point was, that although voltage is a factor, in the end, it's about current.

No voltage, no current. You should understand that if you are what you claim to be.

I found this presentation:
http://www.publicpower.org/files/PDFs/M ... odyrev.pdf

These guys are saying that it's more about current than anything else. They list the primary factors as amount of current, where the current flows, and the time the current flows. All their charts are listed in terms of current too.

Yet, the very first chart on page 6 shows current on one axis and voltage on the other. Did you miss that?

In practical terms, you're going to need some higher voltage, yes, since electrocution will likely happen from skin contact. Sure, but still, the current flow, location, of the flow, and time will determine the severity of the injury. You cannot pinpoint a voltage value that would kill, you can do that with current.

Actually, yes I can. It is generally considered that 70Vac is the lowest voltage that might cause a fatal electrocution. And, yes, it depends on conditions.

I routinely had to sit through mandatory electrical safety awarness courses, industrial site inductions, and had to carry a site safety passport issued by a third party training organisatiion. It was mandatory and has to be renewed at no less than two year intervals. In our case, it was Eastern Training Services Ltd. who provided the training.

Same story from all of them about fatal electrocution voltages.

What can I say? Maybe get educated on the matter if you want to discuss it further?

[Besoeker]

@ Rancid

I have given you actual pictutes on what I have been involved in for over four decades. I have been retired for four months. In my 70th year it was time to let go, I guess. I still do a bit of consulting but this is my branch manager now.



All 33kg (70lb) of muscle and fur......best viewed full screen.
He is a good boy and very athletic. In two strides he can be up to 40mph.
And loves children - one for breakfast, one for dinner............

[Saeko]

No voltage, no current. You should understand that if you are what you claim to be.

That is completely false. Current can definitely flow through vacuum where the voltage difference between any two points is zero.

Somehow I don't think that you are what you claim to be.

[Rancid]

No voltage, no current. You should understand that if you are what you claim to be.

I do understand that. I never made a claim to the contrary.

The issue is, you're still not understanding my claim/point. It's a nuanced point. This is illustrated by the presentation I posted.

The amount of current, the location of the flow of current, and the time duration of this flow of current ultimately determines the lethality of a shock. The voltage required for a lethal shock will be different depending on these factors (a long with a few other factors of course, but those 3 are the main factors).

Example:
If you complete a circuit by grabbing one electrode with your right hand, and the other with your left hand. The voltage required will be pretty damn high to get a significant amount of current to flow through your heart. In addition, that source, if not an ideal source (which it won't be), needs to have a large charge capacity to sustain a high current through your body. On the other hand, if we attach tiny electrodes directly to your heart, the voltage required to get a lethal current will be much much smaller. Also, the charge capacity of that source doesn't need to be as large as in the previous case.

Overall, it's harder to say how many volts are high enough to kill you compared to how many amps are required to kill you. That is why I'm saying it's better to speak in terms of current. Once you are talking in terms of current, there are fewer factors to have to consider (like, amount of current, location of flow, and the duration of flow). It makes quantifying the dangers of electricity easier. That's why you always see people quote the number of milliamps it takes to stop the heart, not the number of volts you have to put across it.

Perhaps my point is nuanced to the point where it doesn't matter in the discussion of general electrical safety (volts or amps, if you're not careful, you're dead either way, sure). Sure, I'll buy that. However, I've not said anything that is not true from a physics standpoint.

[Besoeker]

Example:
If you complete a circuit by grabbing one electrode with your right hand, and the other with your left hand. The voltage required will be pretty damn high to get a significant amount of current to flow through your heart.

As I posted earlier, most people in the field consider 70Vac to be the minimun level that might result a fatality. In USA domestic supplies are generally 120-0-120V and in the Eurozone 230V nominal is the norm.
Industrial on your side of the pond is commonly 480V, 3-phase. Here in UK it is, for the most part 400V 3-phase. The domestic 230V is usually derived from one phase of that to neutral. It's enough to be potentially fatal and has caused actual fatalities. With no C involved so that is another of your irrelevances.

Pretty damn high? Your words. It isn't even high enough to be termed medium voltage.

[Besoeker]

That is completely false. Current can definitely flow through vacuum where the voltage difference between any two points is zero.

If true, it is astonishing that ABB make vacuum contactors. Wouldn't they be pointless?

Do you like my branch manager?

[Saeko]

If true, it is astonishing that ABB make vacuum contactors. Wouldn't they be pointless?

Who cares? Just because "vacuum contactor" has the word "vacuum" in it, doesn't make it at all relevant. Note that if you are disputing my claim, you are effectively saying that charged particles can't travel through vacuum.

[Besoeker]

Who cares? Just because "vacuum contactor" has the word "vacuum" in it, doesn't make it at all relevant.

It very much is. The vacuum contactors made by ABB and others is technology used to break current more effectively than air break contactors particularly on medium voltage applications. If you dispute that, take it up with ABB.

Isn't my branch manager an elegant beast?

[Saeko]

It very much is. The vacuum contactors made by ABB and others is technology used to break current more effectively than air break contactors particularly on medium voltage applications. If you dispute that, take it up with ABB.

Isn't my branch manager an elegant beast?

So charged particles can't travel through vacuum. Ok.

[Besoeker]

It very much is. The vacuum contactors made by ABB and others is technology used to break current more effectively than air break contactors particularly on medium voltage applications. If you dispute that, take it up with ABB.

Isn't my branch manager an elegant beast?

So charged particles can't travel through vacuum. Ok.

So challenge ABB about why they make vacuum contactors. And how they break the current path.

In the meantime, here's a little sampler for you to be getting on with.

https://library.e.abb.com/public/8f79cbf685d54f3b4825780f002c763e/VSC%20Product%20Introduction-en.pdf

And here is the manager looking regal:



I should sue him for dereliction of duty. He was supposed to be looking after the two little grand girls - not posing for the camera........vain beast!

[Rancid]

With no C involved so that is another of your irrelevances.

The only reason C is irrelevant, is because you are limiting the conversation to mains power. Where in practical terms, C is fucking huge. That is, a sustained current draw with no significant spiking will normally not cause a significant droop on the line. However, if you expand the discussion outside of power lines, say we talk about something that is a bit lower power, like electronics say, a TV, computer, or home appliance after mains voltage has been stepped down and possibly converted to DC, it most certainly is a factor.

I would never touch a 1F capacitor charged to say 30-40V. I could easily touch a .000000000001F charged to the same voltage, and likely not even feel it.

[Besoeker]

C is irrelevant because you are limiting the conversation to mains power.

And you appear to be excluding it.

Isn't my dog a handsome fellow in his smart Tux?

[Rancid]

And you appear to be excluding it.

In a sentence, you are covering a special case, while I'm covering the general case.

Many of the factors I'm talking about become irrelevant because it's a high power line. It's not actually excluded in this discussion, it's just that power lines are basically a special case that simplifies much of what I'm talking about. It's actually easier to understand things for this reason. It's also easier to attempt to quantify the dangers of power line via voltage. However, this cannot be done as easily in lower power scenarios (which is the world I largely live in). My point is, there is more to the story when you look at stuff beyond high power transmission lines.

The capacity of mains power supply is so large, it's simply not as interesting to talk about. Also, it's pretty obvious to even the layperson that power transmission lines shouldn't be touched. 120VAC @ potentially 20Amps (assuming you live in the US, and touch your outlet, and have a breaker) is pretty bad news no matter how you describe it (voltage or current).

Again, a very simple example of my point:

A 1F capacitor charged to say 30-40V is dangerous. While a .000000000000001F charged to the same voltage, is not dangerous (you may not even feel zap). It's the same reason you don't drop dead when you rub your feet on the carpet and charge yourself up to 5000V then discharge on a doorknob. This is exactly why we GENERALLY cannot speak of the lethality of electrity in terms of voltage. This is why it's actually easier/better to describe the lethality of electricity in terms of current. You can make more technically correct generalizations with current, rather than voltage.