How To Prevent Short Circuit With A Simple Wire From One Outlet Prong To The Other

Discussion in 'Circuit Help' started by shannon, Jan 5, 2017.

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1. shannon

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hello .... I am new ... I am not an electrician, but a hobbyist ...

For the sake of discussion, I want to take a copper wire and run it from one prong of my 110 outlet to the other prong (I will not really do this in real life!!). This would of course blow a fuse (and if the wire is not insulated would be a very serious shock hazard!!).

My question: is there some type of common "device" that I can place in the simple circuit to prevent a short circuit?

thanks, Shannon

shannon, Jan 5, 2017

2. Gryd3VIP Member

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A fuse

Gryd3, Jan 5, 2017

3. Alec_tVIP Member

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A resistor would be one possibility. Or a lamp, or a motor, or .......
But mains voltage can KILL you. If you have to ask such a question you should NOT be messing with mains sockets.

Alec_t, Jan 5, 2017
4. MinderVIP Member

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What is the reason for using such a device in B?
M.

Minder, Jan 5, 2017
5. shannon

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I respect what you are saying ...

regarding putting a resistor in the circuit: how do I know how "big" of a resistor I need to prevent the short circuit? Or better yet: does there exist a "smart resistor device" that would adjust depending on the load?? So, for instance, if the load is 0 (as in my scenario A), the device would supply maximum necessary resistance to prevent short circuiting, but if the load were greater (such as placing a common room lamp on the circuit) the device would decrease the resistance to none.

thanks for your time ...

shannon, Jan 5, 2017
6. shannon

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simply to prevent short circuiting ... thanks, Shannon

shannon, Jan 5, 2017
7. Alec_tVIP Member

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A resistor having any finite resistance will prevent a short circuit which, by definition, has ~zero resistance.
What you are looking for, I think, is a current limiter.

Alec_t, Jan 5, 2017
8. shannon

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your comment of "any finite resistance will prevent..." leads me to ask a converse question please: Will a short circuit ONLY occur IF there is 0 resistance?

shannon, Jan 5, 2017
9. garublador

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Right now you're sort of talking semantics with no real context. A short circuit means you have a "low" resistance between two nodes. What exactly "low" means will depend on your circuit.

garublador, Jan 5, 2017
10. Alec_tVIP Member

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Colloquially, a 'short circuit' is just a current path able to cause damage or blow a fuse. Theoretically, it is a current path of zero resistance. So what do you understand by the term 'short circuit' ?

Alec_t, Jan 5, 2017
11. hevans1944HopVIP Member

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Both your SCENARIO A and SCENARIO B show "light weight copper wire" connecting to the convenience outlet. There are devices that show a small resistance that abruptly increases with increasing current: polyfuses. But it would help if we knew what you want to DO with that "light weight copper wire" and exactly what kind of wire is it? Are you perhaps planning to string some fine insulated "magnet wire" around your house? Is your fire insurance paid up?

hevans1944, Jan 5, 2017
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Well obviously the fuse suggestion would work, or if you want a reset-able device then use a reset-able breaker.
M.

Minder, Jan 5, 2017
13. Gryd3VIP Member

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Let's give you some background and terms that may help.

Short Circuit is a 0Ω or *very low* resistance path from one point to another.
To prevent a short circuit, you either need to break this path with a device like a breaker or fuse or introduce a higher resistance into the circuit.
A 'load' is anything that can be powered... a light-bulb, motor, resistor, speaker, etc... One of the properties of a load is resistance, so you could technically power something to reduce/eliminate a short circuit.

If you want a safety device, a fuse or breaker.
If you want something to experiment logically with... *anything*.

Now that I've covered this... there is another problem. There was previous mention about how low something can go to be considered a short-circuit.
If you have an outlet capable of providing 15Amps, then a typical short circuit will pull 100s of Amps and immediately blow the breaker (which is further up-steam from the plug)
That is a short-circuit of course... but what if you plug in a huge power tool that tries to pull 30Amps?
The breaker further up will still blow.

This is where they grey area comes from.
Both situations cause a blown breaker and is difficult to judge if it's merely a 'surge' or a 'short-circuit' that caused the breaker to blow.

So... talking about this we now need to amend an earlier suggestion. Simply adding *any* load to the circuit will not help *if* the load tries to pull too much current. What is defined as *too much* will entirely depend on the circuit you are connecting it to. It could be as little as a fraction of an amp requiring many thousand Ω, or it could be higher than 10Amps requiring very few Ω.

Gryd3, Jan 5, 2017
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14. BobKVIP Member

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In diagram B, one device you can put there to prevent a short is an air gap. Simply seperate the in and out wires by a cm or so and there will be no short circuit.

The question is, what do you expect this loop of wire to do? Do you expect current to flow through it? If so, how much?

Why so mysterious?

And, by the way any lamp or other thing that you plug into your outlet is a loop of wire with a device in series that prevents a short circuit. So, if that is all you want, just plug in a lamp.

Bob

BobK, Jan 5, 2017
15. (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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An open circuit or half a brain.

(*steve*), Jan 5, 2017
16. Tha fios agaibhVIP Member

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It depends on the load you want to protect.

Short circuit protection is already incorporated into your homes circuit breakers in the electrical panel. This usually limits current to 15 or 20 amps, but a supplemental fuse can also be added to your load (whatever is plugged in), that would limit the current draw even more during the short circuit event. For example; A supplemental 1/2 amp fuse would limit the current to about 1/2 an amp, if it shorted beyond the fuse.

Tha fios agaibh, Jan 5, 2017
17. davennModerator

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This a really bad thread
thought experiment or not

some one mite read it and be stupid enough to actually try it

it is closed for further comments pending possible deletion

davenn, Jan 6, 2017
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