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#### brian john

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First as apprentices you should be using proper terminology

You either have a phase to neutral short
Or a phase to phase short.

Where was your instructor in all this? When I taught classes I checked and tested everything prior to energizing.

#### brian john

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I did ohm the circuits out and didn't find any shorts before we energized them. Also, I am trying to do research to learn what the proper terms are and trying to understand what happen. I do not think that he hooked the neutral wire up to the light switch but i believe that he hooked both hot wires up to the switch. If you know where I might learn more about phase to neutral shorts and phase to phase shorts I would greatly appreciate it.
Then you obviously over looked a step in your testing.

In addition, there were no sparks just hearing the wires vibrate then the breaker tripped.
That is what we call a bolted fault.

As far as my teacher, lets just say that I wish he had better teaching skills too.
He is still culpable in this error in energizing a circuit.

#### brian john

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Phase to neutral is exactly like phase to ground. There is no resistive load between the hot and neutral
There is a "resistive load but the resistance is very low, near "0"

thus nothing to limit the current so the current is infinite and trips the breaker as it passes 15 amps with the magnetic feature on the breaker.
That also is not true the current is limited by the impedance of the supply therefore no infinite and the instantaneous trip current (he magnetic portion of a molded case circuit breaker) typically on a 15 amp circuit breaker is 150 amps )10 times the rating of the CB.

Troy Google NEMA circuit breakers, they have a decent manual on circuit breakers, explaining how CB's work. It will be very helpful for you.

http://www.nema.org/pages/default.aspx

#### brian john

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Yes if you want to call the minuscule amount of impedance that is in the conductor, then yes there is a small load on the circuit.

Theoretically it is infinite the current would surge till the breaker trips or the supply fuse blew from the supply side. If neither of these existed it would keep drawing current till the conductor heated up and burned itself up.
The MINUSCULE amount of impedance in a conductor is not minuscule it is all part of the circuit and is considered in any arc flash analysis and coordination study.

It is NOT theoretical, the current is limited by the impedance of the supply source and the impedance in the supply side distribution system. We are talking actual facts and how electrical circuits work, now you can make excuses for errors in your post or you can learn.

Your choice, I tried to point you in a direction for you to broaden your knowledge, take it or leave it.

#### brian john

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Being rude will never get me to listen to you.
Rude? Pointing out you are posting inaccurate information? You do not have to listen you can be wrong the rest of you career. Just seems a dumb way to live.

#### brian john

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All the ballast are good. We know it was how he wired the switch just trying to understand what happened and why.
And this was explained by several posters somewhere in your set up there was a wiring error, somehow in your testing the circuit you over looked this wiring error.

#### brian john

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Yes we know that there were errors made, in my testing of the circuit and in wiring of the switch (which we can fix for future events), what I am trying to understand if what happen because of it. What made the wires vibrate and why did it take so long for the breaker to trip. Just trying to increase my knowledge and so if I trouble shoot something in my future career I have a proper understanding of the events.
When you have a instantaneous high current occurrence in a circuit and the conductors are not tightly bound such as in NM or MC there is a strong magnetic field and the two conductors move away from each other very fast and this results in the conductors slapping the side of the conduit.

This will happen when energizing motor, transformers or any high current loads especially a fault.

I can post a video of this next week when I get into the office, if you like.

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