Talk:High voltage

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Electric field[edit]

While we would probably agree that 33kV/cm is just a ballpark figure, we should be somewhat careful to what we attribute the potential discrepancies. Namely, the contents of air, pressure, humidity, etc. can change this value significantly. However, we should not think of this number as potential between two nodes divided by the distance. That is of no significance. The actual, meaningful, value is the limit of that: dV/dl which is the local electric field and has the same units [kV/m]. It is true that for a given charge (related to the potential) smaller radius will exhibit higher fields due to higher charge density at the surface. However, the wording present in the article, I believe, is somewhat confusing and misleading and obscures the actual relevant breakdown mechanism.

Yes, with sharp points the field at the point is high, even at low volts/distance. But for large radius spheres, radius somewhat larger than the spacing, it won't be so far off. The number I remember is 10kV/cm, which might be closer for not so small radius objects. (Where the field could be 33kV/cm.) Gah4 (talk) 04:46, 5 September 2017 (UTC)


some people seems to have problems with the claim that ppl routinely survive taser shocks. well, it's a valid claim -- as far as i know, stairs are not considered lethal contraptions, and more people have died from falling off stairs than from being tased.

Well, people routinely survive being hit by a baseball bat, falling down a flight of stairs (did it two or three times when I was a kid), being hit by a car... The fact that less people die from tasing means nothing in regard to its safety. Actually, I would assume that much more people have a mishap of falling down a flight of stairs (per unit time, per unit area) than those that get tased (per unit time, per unit area). Sad fact is that many 'engineers' have no professional dignity not to produce arms (no matter who asks them to), not to produce poorly devised, poorly designed products for propagating political agendas or just being mean to others (bad measurement equipment -- e.g. police-grad /that is non-military grade/ speed radars, teasers, ... ). —Preceding unsigned comment added by (talk) 00:22, 3 December 2009 (UTC)

It is okay this?[edit]

"The largest-scale sparks are those produced naturally by lightning. An average bolt of negative lightning carries a current of 30-to-50 kilo amperes, transfers a charge of 5 coulombs, and dissipates 500 megajoules of energy (enough to light a 100 watt light bulb for 2 months)."

But 30 kA is not about 30,000 Coulomb in 1 (one) second? How it can be just ONLY 5 Coulomb? —Preceding unsigned comment added by (talk) 14:23, 10 April 2009 (UTC)

Yes, 30kA is about 30,000 Coulomb in one second. If 5 coulomb is transferred, then the lightning arc connects for 160 µs. The article is perfectly correct. (talk) 23:40, 24 November 2009 (UTC)

Why are citations missing in this 'lightning' section? Lightning is actually pretty poorly understood phenomenon and there is not that much theoretical modeling of it. Where do these claims come from. —Preceding unsigned comment added by (talk) 00:24, 3 December 2009 (UTC)

In digital electronics, a high voltage is the one that represents a logic 1[edit]

As user: Wtshymanski goes to an edit war rather than discusses, I start this topic. The article High pressure does not state that these are high pressures, but what is means in engineering and science. Although High pressure area also exists, nobody adds references like "in meteorology, the high pressure is blah-blah-blah" to the "High pressure" article, because a high pressure in meteorology has different connotations and effects. And here, we have virtually the same. There is little sense in such references to digital electronics, because the rôle of high voltage level has nothing to do with high (i.e. dangerous, or problematic) electrical tension, just a coincidence of terms. Is there reliable sources supporting claims that digital electronics' "high" is the same "high voltage" we have the article about? If there aren't, then I remove Wtshymanski's phrase again. Incnis Mrsi (talk) 17:41, 21 August 2011 (UTC)

I disagree. It's important to show that "high voltage" is a term relative to its context, and it's extremely useful to show that sometimes "high" is several hundred millivolts. No-one claims this is dangerous. --Wtshymanski (talk)
This is even less a "high voltage in the context" than an anticyclone is a "high pressure" in the context of meteorology. The "voltage" may mean either the potential difference between two conductors (or even an absolute value of it, as in "high voltage") or the potential of a conductor relatively to the ground (as in "logical 1"). I could say that it is likely a linguistic confusion and an original synthesis based on it. Which languages (but English) have terms similar to "high voltage" for the digital "logical 1"? Incnis Mrsi (talk) 14:52, 22 August 2011 (UTC)
What is the relevance of other languages? Google Books gives hundreds of hits for the exact term "logic high voltage". --Wtshymanski (talk) 15:05, 22 August 2011 (UTC)
Just to disprove that it is the same "high voltage". Google gives millions of hits for the exact term "sea lion", so consider opening the lion article and adding a reference to lions in the maritime context. Incnis Mrsi (talk) 09:22, 23 August 2011 (UTC)
Not relevant. This article is about voltage. --Wtshymanski (talk)
I've reworded, hopefully it's now clearer. Andy Dingley (talk) 18:31, 23 August 2011 (UTC)
I find it unusual, to say the least, to describe "logic high" as "high voltage". Obviously the term "high" is relative - if my signal level is in microvolts, I may well describe 0.5V as "high", but that would be in a very clear context. In the context of a logic board, logic one is not high voltage, it's <=Vdd; I would expect high voltage to mean significantly above Vdd, such as may be used for a line-driver. I don't think any mention of digital levels belongs on this page. GyroMagician (talk) 19:29, 24 August 2011 (UTC)
──────────────────────────────────────────────────────────────────────────────────────────────────── WHere do you want to set the cutoff? 66,000 volts? 1000 volts? 240 Volts? 120 Volts? 48 Volts? 12 Volts? ....--Wtshymanski (talk) 19:45, 24 August 2011 (UTC)
There is no need to do anything of the sort, you're just putting this hurdle forwards to be awkward. "Logic high" might yet need to appear in an article on high voltage, but only to distinguish it for obviously not being a high voltage by any absolute measure.
"High voltage" is well defined and easily referenced, but it varies by context and so several values for the "cutoff" should rightly appear in this article, per section. For safety purposes, local wiring regulations generally define 50V as the cutoff for "hazard". For electronic design and protection from unwanted arcing effects, 500V or 1kV are considered the limit - above this unwanted things can happen. For relying on the useful effects of HT to make a device work, it could be a few kV. All of these voltages are different, but they're different for a reason, they have citable references, and they rely on a voltage (even the 50V) that is still an absolute high voltage. There is no contradiction here. Yet logic high is quite outside this - no-one (except you) credibly claims that the voltage indicating a logic 1 (in logic terms) is also a high value (in voltage terms). Andy Dingley (talk) 21:55, 24 August 2011 (UTC)
I was quite happy to have every possible definition of high voltage give a context and a number, but on Wikipedia we know there is only ONE RIGHT ANSWER and I'm curious to see what it is. Right, 50 volts is high voltage. Never mind that you can completely destroy a diode junction with only one volt, or kill a cell with a stray potential of one volt. --Wtshymanski (talk) 01:32, 25 August 2011 (UTC)
I think everyone here agrees that "high voltage" is a relative term, and that in a specific context any voltage &gt0 could be considered high. But the term is also used more generally, as this page describes. In *common usage* high voltage has several different definitions. Logic 1 is not *commonly* described as high voltage - I think you're the only person using it that way. Remember, this is Wikipedia, not Wtshymanskipedia (or GyroMagicianopedia) - what we write has to be backed up by verifiable, reliable sources. Logic 1 == high voltage needs a source. GyroMagician (talk) 06:51, 25 August 2011 (UTC)
I calls 'em as I sees 'em. "Logic high voltage" seems be a phrase much used by the mumbltey authors of books turned up by Google, so I'm not entirely insane. --Wtshymanski (talk) 14:15, 25 August 2011 (UTC)
Isn't that the point: logic high voltage != high voltage ? GyroMagician (talk) 19:14, 25 August 2011 (UTC)

It seems we still do not agree here. What is your argument for including "logic high" in a page about "high voltage"? I would define high voltage as any potential needing some special consideration. In the case of a logic system, high (e.g. TTL>2V) is merely the name of a logic state (a.k.a. true or 1). There is no special consideration needed for logic high, and no safety standards or restrictions related to it's level. I really don't understand why you think it belongs here. GyroMagician (talk) 07:32, 11 October 2011 (UTC)

Suggest merge[edit]

Someone recreated Extra high tension. It should be merged back here again as it's no more than a definition which was already included in this article. --Wtshymanski (talk) 07:30, 3 January 2012 (UTC)

Recent insistence on making a change, now twice reverted.[edit]

The text, going all the way back to near the beginning of the article's history, says:

Electrical transmission and distribution lines for electric power always use voltages significantly higher than 50 volts, so contact with or close approach to the line conductors presents a danger of electrocution.

"Electrical distribution lines" is a very broad term. In the United States, transformers on power poles reduce higher voltages via a center-tap transformer so that three lines (plus a ground line) reach the customer from the street. Schematically the terminals would be H----G----J. A 240 volt appliance such as an oven will be wired to use the potential difference of 240 volts that exists between H and J. !20 volt outlets will be wired either to H and G or to J and G, either of which yield a potential difference of 120 volts. (H is a black wire, G is a white wire, and J is another black wire.)

The passage quoted has to be understood in context with other information—the voltage that is sufficient to break down the insulating properties of human skin. Humans with dry skin can safely handle, e.g., the 12 volt current present in a car battery. Coming in contact with a source of AC or DC potential of 80 volts (one hand on each contact) will drive electrons through the body and cause an unpleasant shock. 50 volts is the point at which a significant number of people will begin to experience an unpleasant shock.

Contact with either of the "hot" lines with one hand and the "cold" line coming from the power pole will subject a person to 120 volts. If hands are wet the shock may be deadly. One hand on each of the black (hot) lines will yield a 240 volt shock, which is deadly.

The recent ISP editor wanted to change the article to mention 50 kilovolts. That voltage is much higher than would normally be present even on the wires between telephone poles, and would not merely present a "danger" of electroduction. It would produce a certainty of electrocution.P0M (talk) 00:57, 12 September 2013 (UTC)


"Voltages greater than 50 V applied across dry unbroken human skin can cause heart fibrillation if they produce electric currents in body tissues that happen to pass through the chest area."

This statement seems assumed that voltage can cause fibrillation. It is known that milliamperes can cause ventricular fibrillation, but what about voltage? While voltage may affect the minimum amount of milliamps required to cause fibrillation, it does not directly cause fibrillation. If the statement was intended to show the effects of voltage on the heart, the statement should be revised to clarify the relationship of voltage AND current on the heart. Later in the article, it gives examples of millions of volts touching someone and doing virtually no harm, yet this number of "50 volts" apparently causes heart fibrillation. Please reword this to represent facts and add a citation.

-- (talk) 16:06, 8 November 2013 (UTC)

Good observation. The basic physics involved is that a high voltage static charge can be applied to a human body without damage if the transfer rate of electrons to the body is not high. That's what happens when somebody stands on a demonstration device that charges the individual by charging the apparatus on which they stand. The electrons stay on the surface because they repel each other. (Charged hairs also repel each other so a "fright wig" is produced.)
When high voltage current passes through a conductor, the electrons all flow over the surface of the conductor due to their mutual repulsion. At lower voltages the electrons can disperse throughout a conductor.
Lightning strikes are of extremely high voltage, but they do not pass safely over the surface of a human body.
The physics is more than should be in the article, so the article needs to be rewritten to make it clear than heart problems will occur when voltage is sufficient to break down skin insulation, and safe high-voltage contacts are generally low amperage and static. P0M (talk) 18:17, 8 November 2013 (UTC)
I just tweaked parts of the article pertaining to the potential misunderstanding mentioned above. Take a look.P0M (talk) 19:43, 8 November 2013 (UTC)

HV-Circuit in automotive[edit]

I would appreciate a short explanation about the HV-Circuit in cars. E.G. Does a HV-Ciruit exist in Hybrid-Cars only? What is the purpose of this circuit? — Preceding unsigned comment added by (talk) 08:50, 17 March 2016 (UTC)

Hybrid and electric cars normally use somewhat higher voltage, to reduce loss in the wiring. Also, charging systems often use higher than 120V (normal US power line voltage) to enough power for a fast charge. Gah4 (talk) 04:52, 5 September 2017 (UTC)