If I understand this correctly, you wired the circuit but when you turn on the breaker it instantly trips? I'd think you have a bad breaker (unlikely), short to ground somewhere or you wired something incorrectly? In the panel, assuming you used NM cable, the red and black wires would go to the breaker, the white wire to the neutral bar, and the bare copper wire to the ground bar. Any chance you nailed through the cable when you installed the staples? How about in the box you used for the receptacle? What happens if you disconnect the wires from the receptacle, cap them off, and turn the breaker on (that would eliminate a defective receptacle?

As an aside, it sounds like you might have a bit too much going through a 50 amp sub-panel. If I counted right, you have two 240 volt circuits and five 20/15 amp circuits. What are these for? It's kind of like the old joke about money, "how can I be out of money, I still have checks left?" Just because there are spaces in the box, doesn't mean you can fill them. ;-(

If none of this helps, you might want to post a few pictures of the panel and the junction box for the dryer receptacle.

We agree as to how the circuit is wired. 3 of the 20s are dedicated for 2 bathroom ceiling heaters and a bed room heater. None of which are being used yet this year. The other 20 is a GFCI for the laundry room / utility outlets and lighting. The 2 15s are the circuits for two bedrooms one of which is a guest room.

I removed all the breakers and placed the 30 at the top of the box. It stays on but as soon as I reinsert another breaker, it trips.

Everything works fine without the 30. I will take a picture. Thanks for your help.

It is illegal to put laundry room (15/20A 125V) receptacles and lighting on the same circuit. The laundry room requires a 20A circuit for receptacles with NO OTHER OUTLETS on it.

The laundry room outlets and lights are on a separate 20 amp GFCI circuit. The dryer is on its own circuit. The other circuits in the box feed areas in other parts of the house. Either way, this does not help solve the problem. It is easy enough for me to move the laundry room lights to a different circuit. I'm wondering if it has to do with load balancing. My other option is to run #8 or #6, depending on the distance, from the original dryer circuit at the main box.

AGAIN, you may not put lighting or other outlets on the laundry area receptacle circuits. It's against code.

Load "balancing" is not the issue (especially with no load to be balanced). I suspect you've screwed up something with the installation. Is this a GFCI by any chance? Almost certainly a wiring fault (neutral-ground touching or the load netural misconnected, or the GFCI neutral misconnected).

Excellent point, greg.

I'm not sure. It is a square d 2 pole 30 amp. The box is a square d. It fits in the box and the knives all match. If I leave only that breaker in and remove the rest there is no problem. In either case, there is no load as I have yet plug in the dryer.

Divide and conquer. Are there wires attached to the breakers? Try removing them from the breaker terminals but leave the breakers in position.

SquareD makes at least three different kinds of panels. QO and Homline are distinct units (the breakers are not interchangeable).

Electrical power is always going to take the least resistance to ground if properly grounded. In this case it appears that the grounding is doing its job and tripping the circuit breaker as it is designed to do so. Shut the breaker off unhook the wires from the breaker and ohm out each 120 volt hot wire to ground. The leg which shows fault to ground is the guilty one for the tripping. If all else fails send me a conference call or book a date and time and I can diagnose it with your help on the other end.

Thanks to all for your responses. I work on this probject as time avails.