Please help! I just installed 2 new 3 way switches and a new light. Both switches can turn the light on and off. However if both switches are in the up position, the breaker trips. I've checked and rechecked the wires. They are correct per my Black & Decker Complete Guild to Home Wiring, and the first few pictures on google that came up. What could be the problem?

 

Welcome to the forums! You need to determine "line" and "load". The line will be the incoming hot black wire, and the load will be the black wire going to the light fixture(s). The other two wires are travelers and are placed on the brass screws at any combination. The line and load must be on the black or andonized screw. If the switches are tripping the breaker, pull them away from the box to make sure you don't have a ground wire touching something it shouldn't. It happens.

 

Given the large number of ways to wire a 3-way circuit we would need a lot more info if Larry's suggestion doesn't work.

 

Even if the switch wiring was mixed up.... you wouldn't trip the breaker.
That tells me something is probably hitting ground like Larry mentioned.

 

All the switches are still pulled out, so I don't think I have a short.....

So here's more on the setup....

It's a double box that already has one 3 way switch that controls other lights. The other switch that was in the box was not connected to anything.

So I have the black power line going to both switches, to the common lug.
All 3 white wires are wire nutted together as is the ground wires.
The new 14/3 wire black and red are lugged to the travel terminals.
The white leaving this box goes to the white wire on the new light.
The black wire leaving this box goes to the light box and is hooked to the white wire from the other switch. (Marked as hot)
The red wire leaving this box is hooked to the other switches red wire in the light box.
The ground wires are all wire nutted together in the light box.
From the other switch box, the ground is hooked to switch.
The red and white (marked hot) are hooked to the traveler lugs.
The black is hooked to the common.

Again to me the oddest thing is that both new switches can control the light, only when both switches are up does the breaker trip.

 

Your description doesn't sound correct. Black of power in should be connected to the common. That sounds correct but at the other switch black power out 2-conductor cable should be connected to common. That doesn't sound like what you did?

 

This makes perfect sense. Power to common. Red and black as travelers. Neutral carried thru.

Now at the other end you have red and white as travelers. How is that possible ?

At the second location.... red and black need to be travelers and the white gets carried thru as neutral.

 

Sorry didnt mention, light is in the middle of the two switches.

Sorry I copied that from the Internet..... Not,trying to break any rules, just don't know,how else to show what I did.

 

It's fine as long as you give credit, which is subliminally posted. I still say you have an exposed wire somewhere touching the metal box or a ground.

 

If you did it that way it is correct and should work (though technically it no longer meets code which requires a neutral even if not needed at both switches when cable is used).

As Larry suggested sounds like something shorting. Have you pulled the light loose? Have you triple checked you didn't swap any wires?

 

As long as the neutral wire goes directly to the light..... all the rest of the wiring is hot.
So that means mixing up the wiring on the switches cannot cause a short.

The light works fine with switches in the one position. That says light is good.

At this point I think I'd check the travelers for a short to ground. It sounds like one may have an issue.

If it trips with the switches out of the box and not connected to ground..... it's a wiring short.
If it only trips with the switches in place or grounded then it could be a bad switch.