I am currently working on some "upgrades" to one of the rooms in my house. Something as simple as adding 1 light has turned into a rather large project. For whatever reason half the house seems to be wired together.

To sum it up, I've pulled and re-ran half of the wiring but never touched the source. The line from the Panel is 12-3. I haven't pulled the breakers to look to see how the 12-3 is attached, but I assume the 12-3 is coming off of two different twin breakers. When I flip one of the breakers on, everything works fine. As soon as I flip the other, it blows both. I assume the black is off of one breaker and the red is off the second breaker, but not sure.

I've attached a rough outline of the wiring path and the breaker that is tripping. Breaker #27 is the one that is currently on and working. Breaker #26 is the one that blows both 26 and 27 when it is flipped on. Any idea's on what may be happening?

 

Aren't those twin/tandem?

 

You are working with multiwire branch circuit. The three wire connects the panel to the junction box. At the junction box the circuit is split up. One circuit is red and white. The other circuit is white and black.

It is very important that the neutral/white connection be very solid. If your circuits lose the neutral connection you could get up to 240v on a 120v receptacle. This would cause damage to any connected devices.

Ray..... he means two and three wire.

 

To avoid confusion I have deleted my post.

 

So then basically at the junction box, I can take half of what's connected and put it on the red/white side, and the rest will go on the black/white side.

 

Yes.... that's how the circuiting works. Like I mentioned.... make sure you make a very good neutral splice. You do not want that to open.

 

Thanks for the help.

In its current state, live off of the one breaker, will this be ok until the morning, or do I need to head up there and change this now?

 

The two circuits can be run independent of each other.

What you need to locate tomorrow is where you've connected the red and black.
The circuit will be ok until tomorrow.

 

Well provided nothing comes loose, it looks like everything is ok. I found the black/red error and separated them. Getting the six #12 neutrals was a challenge though. Not much room for forgiveness on the wire lengths.

Thank you again for the help.