Am going to run a new circuit about 115' underground to middle of front yard for xmas decorations and such. Will have 2 recepticals. What size wire and breaker will I need , and does it need to be in conduit?

Since the xmas lights will probably be on for 3 hours or more, the circuit needs to be derated by 80%, so a 20 amp circuit should have no more than 16 amps or 1920 watts of load.

One two wire circuit, 120 volts drawing 16 amps at 115 feet will need #8 copper wire, to keep the voltage drop below the recommended 3% for a branch circuit results in 2.8%Vd at the end of the circuit.

If you run 1- 20 amp circuit, using a 20 amp GFI breaker, to protect the entire circuit, (a GFI outlet will not be sufficient for this situation), you can:

1.Use #8 UF 2 wire with ground cable, can be 12 " deep.

2. Use a 3/4" PVC conduit, with 2-#8 THHN/THWN and 1-#10 THHN/THWN green for the ground (or XHHW for both), 12 inches.

3. Use metal rigid conduit with the wire from option #2, you can go 6 inches deep.

If you need more than one 20 amp circuit, options #1 & 2 do not apply. UF cable then goes to 24" deep, and PVC conduit goes to 18" deep.

Any buried cable or conduit should have a warning tape several inches above it.

Thous metal conduit is the most expensive raceway to purchase and install, sure allows someone to save back pain by digging a shallow trench.

And may be best to check with any local codes due to local soil conditions.