Talk:Short circuit

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Too technical?[edit]

This article was listed on Wikipedia:Requests_for_page_expansion as being too technical, so I tried to make it a little more accessible. I replaced the following paragraph with a summary statement, but thought I would leave it here for reference.

Wire sizes specified in building and electrical codes are usually determined by their ability to carry the rated load without overheating (called the "ampacity"). Additional wire capacity may be used in the interests of efficiency. In the case of very long wire runs, the ability to carry the current to trigger the breaker must also be considered; it is possible to create a long wire run that will carry the normal working load and provide sufficient voltage at the load, but when overloaded will dissipate the excess current in heating the wire, while still below the wire's ampacity and the circuit breaker's limit current. This occurs when the voltage drop in a short circuit condition equals the supplied voltage and the resultant current flow is below that of the load limiting device. In this case the wire must be oversized to ensure that the circuit protection device operates. Such considerations apply to runs exceeding several hundreds of meters.

--Bcordes 13:56, Jun 23, 2004 (UTC)

Really?, If you want "technical", you should read some of the medical articles on Wikipedia, that talk in a language that only doctors and wannabe doctors understand. Having said that, this article uses only US references, as in, the rest of the world calls "ampacity", everyone else in the world calls current-carrying capacity. Trumpy (talk) —Preceding undated comment added 09:19, 25 September 2012 (UTC)

Fuses don't prevent short circuits[edit]

Picky detail: Short circuits are not prevented by fuses and such. The short circuit occurs and the circuit then opens because the fuse blows. The fuse prevents damage from a short circuit.. — Preceding unsigned comment added by 66.227.89.85 (talkcontribs) 22:04, September 27, 2004

And your point is? All fuses and circuit-breakers conform to a simple I²t curve, the higher the current, the quicker the protection will operate. Trumpy (talk) 09:30, 25 September 2012 (UTC)

definition[edit]

"charge is allowed to flow between a phase and the electrical earth or between two phases" - this doesn't seem very accurate to me - a short circuit can occur in lots of other combinations of conductors (phase to neutral, or any number of other possibilities in the case of more complex apparatus especially DC-powered systems). The "unintended path" definition sounds much better. Any objections to me rewording this? — Preceding unsigned comment added by Ali@gwc.org.uk (talkcontribs) 03:16, January 8, 2005

Does neutral not count as a phase? I know much less about AC than I do DC. I also agree that the "unintended path" definition is more general, if less "clinical". If you've got suggestions for a better formal definition, I'd love to hear/see them... Bcordes 16:57, Feb 7, 2005 (UTC)

I think too much emphasis is placed on a short being unintentional. There are many instances (such as illustrated in the final two paragraphs) in which a short is desired. One technical definition might be, “A short is when two nodes of a circuit are directly connected.” In many cases this is a fault and unintentional. Also, the term “resistance” is used in the definition. I feel a more accurate term would be impedance. An ideal inductor has no resistance, but it is not considered a short. In a DC case however, this inductor would act as a short. I also argue that in a transformer (or power outlet as in the article) there is already very low resistance between the phases; but there is a large impedance. I offer that impedance be the prominent term used in the article.Mak17f 19:07, 10 December 2005 (UTC)

I completed agree, and in bad form, I reworded the article to remove the emphasis.Rmcii 22:01, 12 March 2006 (UTC)

You guys don't have a clue about what you are discussing, let alone asking for advice on this sort of thing, I've been a registered electrician and HV technician for 25 years. No, neutral does not count as a phase, it is the earthed component in any electrical system. What a short circuit is defined as, is when two (or more)conductors touch together, that should not do so in normal use, creating a fault current, that operates the system protection, on all poles of that circuit, making it safe. If that is too hard for you folks to fathom, don't bother commenting.Trumpy (talk) 09:47, 25 September 2012 (UTC)

definition, intended audience[edit]

I think we should make this page more useful to students in an intro circuit analysis class. I think, in the class I'm taking at least, we use short circuit to mean a plain, zero-resistance wire. E.g.

  • An inductor at steady state is modeled as a short circuit, which to us, basically means a plain wire; a plain line on your circuit diagram.
  • When using Thevenin's Theorem, voltage sources are "shorted", i.e. removed and replace with a plain wire.

These are the only times I heard the term 'short circuit' in this course (I have to admit that I didn't go to class very often, which is why I'm sitting here reading circuits articles the night before the final (the textbook sux)). My only other experience with the term is from the movie about the robot that (who, to be P.C.) got struck by lightning and started to feel emotions and things.

I think where I'm going with this is that this article somehow needs to be sectioned for different audiences and uses: everyday use, and varying levels of technicalness and academicness. But I'm nowhere near qualified enough to decide how to do this, or even to know that this is the right thing to do. — Preceding unsigned comment added by TriniTriggs (talkcontribs) 20:15, December 13, 2005

Virtual short[edit]

I havent heard this term. Are there any refs?--Light current 00:14, 8 January 2007 (UTC)

It is a common term in connection with operational amplifiers, so should be easy to find. There is already a virtual ground article. The present section in this article has about nothing to do with the subject and should be redirected to virtual_ground or deleted. Meggar 00:46, 8 January 2007 (UTC)
No thats virtual earth or ground. We know what that means. Virtual S/C has no meaning IMO--Light current 00:48, 8 January 2007 (UTC)
You really must try to look things up. There are 926 Google matches to "virtual short" and "op amp" [1]. In any case there is nothing salvagable in that section, so to save a vast waste of time it should just be deleted. Meggar 01:00, 8 January 2007 (UTC)
OK its a relatively new term regarding op amps. Thats completely differnt from the electrical engineering notion of short circuits. A very low impedance is not the same as a 'dead short'--Light current 01:12, 8 January 2007 (UTC)

Remove: Also when a short circuit happens people die.[edit]

I think that this statement should be removed. Generally speaking, people can die from the resultant conditions of a short circuit (explosions, fires, etc), but this is not always the case.

Also, it is misleading readers into thinking that a person can cause a short circuit. In most cases if a person contacts two phases or a phase to earth/neutral, the resistance of their body is high enough to even prevent the tripping of over current divices such as fuses or circuit breakers.

It is also breaking a point ( it seams to be inserted in a paragraph about something else). I will remove in a week unless someone else see's fit to remove earlier Blaab 08:59, 25 October 2007 (UTC)

Wires vibrating loudly in their wall conduits[edit]

Clod amateur home electrician me made a loop of his home wires. When I closed the circuit breaker I knew something was wrong as all thru the house the wires were vibrating loudly in their conduits in the walls. One second was long enough for me to quickly open back up the circuit breaker.

So mention this rarely observed brief phenomenon that is certainly forgotten while extinguishing the probably ensuing total house fire. Jidanni (talk) 00:24, 28 February 2008 (UTC)

That is so retarded, I can't even reply once the tears have stopped running down my legs from laughter. Trumpy (talk) 10:06, 25 September 2012 (UTC)

Isc[edit]

I suggest a defintion for short circuit current (Isc). This is used in solar panels.--Linegen (talk) 14:23, 13 November 2008 (UTC)

impedance vs resistance?[edit]

In the opening summary, it says "A short circuit in an electrical circuit is one that allows a current to travel along a path along where essentially no (or a very low) electrical impedance is encountered." Should 'electrical impedence' be changed to 'resistance'? —Preceding unsigned comment added by 67.158.25.23 (talk) 21:49, 14 May 2010 (UTC)

No, Resistance is only valid with DC voltage. Impedance, capacitive reactance and inductive reactance are common with AC voltages and currents. Read your text-books before replying. Trumpy (talk) 09:56, 25 September 2012 (UTC)