Can a 3way switch short?

Hasn't this died down yet?

I too have a piece of paper that says how wonderful I am -- BSEE from University of Washington. The funny thing is, I think I forgot more while at the U than I learned. I wired my first light switch when I was 6 years old...

As JW was busy quoting the NEC, I was Googling for dictionary definitions and reading Wikipedia, etc. After filtering out all the fluff, the one "definition" that stood out said something like "a short bypasses part of a circuit".

I don't agree that a short is always unintentional -- if you intentionally set a crescent wrench on a car battery that would be a short in my book (don't do that BTW).

I roomed in a house once that you needed to turn off three breakers to kill anything and everything. Wonder if it's still there.

Murphy625 said:

I'm not sure what you're asking with that question... But, the fact is that two 15 amp breakers feeding a single conductor would theoretically be capable of delivering 30 amps. IE: 15 x 2 = 30. The 14ga wire would eventually melt and catch fire if that happened.

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You said:

Murphy625 said:

If two different conductors from two different circuit breakers originating from the same phase leg come into contact with each other (lets say via a break in the insulation of both wires running next to each other), what condition would you call that? In such a situation, that condition may go unnoticed for a very long time until special circumstances occurred between the two circuits.

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then somehow you ended up with just one wire.

I have been doing electrical work since 1966. I have done about everything one can think of from wiring single wide mobile home to water plants at 4160 volts and the one thing I have never seen is what you are describing.

Yes I know that industrial maintenance men get to see everything but in most cases it is because they install the mess.

Having done consulting in many plants around my area I too have seen some pretty sloppy work done in the industrial plants. It has been my experience that the reason behind this type of work is the lack of education and supervision. In other words if the boss don't know how can he guide.

Murphy625 said:

I'm not sure what you're asking with that question... But, the fact is that two 15 amp breakers feeding a single conductor would theoretically be capable of delivering 30 amps. IE: 15 x 2 = 30. The 14ga wire would eventually melt and catch fire if that happened.

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Since we are Nitpicking,

That would depend on the length of the wire.

jwelectric said:

You said:
then somehow you ended up with just one wire.

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Imagine 2 breakers feeding 2 wires.. somewhere down the line, the 2 wires contact each other.. Now you basically have a parallel circuit up to the point where the two wires contact.. Further down the line pass the point of contact, you have 2 individual wires again but they are both being feed by the same parallel circuit. Now, lets say one breaker was feeding a bedroom and the other was feeding a bathroom. The bedroom or the bathroom have now effectively become a 30 amp circuit being provided by a 14ga (15amp) wire. Did that clear up what I was trying to say?

I have been doing electrical work since 1966. I have done about everything one can think of from wiring single wide mobile home to water plants at 4160 volts and the one thing I have never seen is what you are describing.

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One of the other posters in this thread commented he had a house that had this problem happen.. but his breakers were on different phases so they popped immediately. That said, I'm sure there are lots of things you have seen that I have not.. I am not an electrician who pulls wire for a living. I've certainly done my share of it, but its not my normal daily job.

My daily job is to cruise forums and nik pick at folks like you! LOL

At my ripe old age all I do is sit around trying to remember those things I have forgotten.
Now let’s see, is it the base times the height or is it the base squared plus the height squared then we have to make a root square…………… no, no, no it is if you have a tree that has square roots then it won’t get very high and you will have to hide the pot in a noose. Yea that’s it and also if you try to borrow money at the bank and they won’t let you sine you have someone to cosine for you. Well let’s not get off on a tangent here.

I still feel sorry for poor ole Oscar because Oscar had a heap of apples and that is all anyone needs to know to find the sine or the cosine.

Lots of fine folks think that ½ equals one half but to the wise they will say that ½ is one divided by 2 or that ½ is the reciprocal of 2

Such nonsense that I once remembered while the young of today can only think about getting horizontal.

This is a little late, but I figured a way this could have happened:

- The hidden switch was the switch at the hot end of the travelers.
- It was left with the traveler that made the visible switch be up to be on connected. This is why it was not suspected to exist.
- The visible switch was used to turn the light on and off.
- The traveler that was never used was connected through the bulb to the neutral when the visible switch was off.
- Over time, the equipment ground wire in the box of the hidden switch came into contact with the unused traveler.
- Because that traveler was never connected to anything but the neutral through a light bulb, it caused no trouble.
- When the hidden switch was flipped, it caused a short to ground, blowing the breaker.

I also found such a hidden switch. It was behind a large china cupboard that I had thought was built in because the former owners left it behind.

quote; It might have been making contact with one of the traveler terminals, and that would be a short;

When the light is on, ONE of the travelers is hot, when the light is off the OTHER one is hot, so if either were touching a ground, it will blow the circuit breaker. You had something else going on. BUT, did you check for continuity between the terminals and the switch housing.