Okay, let's break down the code requirements for running power to your outbuilding. Keep in mind that I am an AI and cannot provide official code interpretations. You should always consult your local electrical inspector for definitive answers specific to your jurisdiction, as they may have local amendments. However, I can give you a good overview based on the NEC (National Electrical Code).

General Compliance & Key Considerations



NEC Editions

The NEC is updated every three years. Make sure you know which edition your local jurisdiction is using (2020, 2023, etc.). Code requirements can change.

Local Amendments

Your city, county, or state may have adopted amendments to the NEC that are more restrictive or have specific requirements. This is the most important point.

Permitting

Most jurisdictions require a permit for this type of work. Obtain the necessary permits before starting. This will involve inspection, which will ensure compliance and safety.

Your Specific Questions & NEC Guidelines


Running Two 120V Circuits to the Outbuilding



Generally Acceptable

Yes, running two 120V circuits from your house panel to the outbuilding is generally code-compliant, assuming the circuits are sized appropriately for the loads in the outbuilding and you follow all the other code requirements.

Load Calculation

You must perform a load calculation for the outbuilding to ensure the two circuits are sufficient to handle the anticipated loads (lights, receptacles, tools, etc.). You need to consider both the general lighting load and any specific appliance loads.

Multi-wire Branch Circuits: You might consider using a multi-wire branch circuit to the outbuilding using a 3-wire (2 hots, one neutral) instead of running two separate 2-wire circuits. This is sometimes more efficient in terms of wire usage. If you decide to use a MWBC, it MUST be on a 2-pole breaker in the house panel that will disconnect both hots with one throw, to prevent a potential back-feed.2. 2" PVC Conduit, 18"+ Burial



Depth

18" is the minimum burial depth for PVC conduit containing residential branch circuits (120V/240V) per NEC table 300.5. So you're good there.

Conduit Fill

Make sure you're not exceeding the conduit fill capacity with your conductors. Using two #10 THHN/THWN conductors, plus one #10 Ground conductor will give you plenty of room in a 2" conduit.

Conduit Body

You must use approved fittings for the conduit system (e.g., couplings, elbows, etc.). Use expansion fittings if there are long, straight runs.

Sealing

Seal the ends of the conduit at both the house and the outbuilding to prevent water and debris from entering.3.

GFCI Protection



NEC 210.8(A)(2)

All 120V, 15A and 20A receptacles in a detached garage or outbuilding that has a floor and a roof (as yours does) must have GFCI protection.

GFCI Protection Methods



GFCI Breakers

You can use GFCI breakers in your house panel to protect the entire circuits. This is a common and easy method.

GFCI Receptacles

You can use GFCI receptacles at the first receptacle box on each circuit in the outbuilding. The "load" side of the GFCI receptacle will then protect all downstream receptacles on that circuit. Important: If you use GFCI receptacles, make sure you use the "load" terminals on the GFCI to protect the downstream receptacles.



Combination

You could use a GFCI breaker and GFCI receptacles, although this is typically not necessary.

Recommendations

GFCI breakers at the house panel can be convenient but can be more expensive. Using GFCI receptacles at the outbuilding is often the most cost-effective approach.4.

#10 Copper THHN/THWN Conductors



Acceptable, Potentially Overkill

#10 copper is generally acceptable for 20 amp circuits.

Ampacity

#10 copper THHN/THWN has an ampacity of around 30 amps (check NEC Table 310.16 and derating factors).

Voltage Drop

At 80 feet, voltage drop shouldn't be a significant issue with #10 for 20 amp circuits.

#12 Copper Option

For two 20 amp circuits, #12 copper is generally accepted, but since you stated that you are an electrician, using the #10 copper is just fine.

Grounding Conductor

A separate insulated equipment grounding conductor (EGC) must be run with the circuit conductors. A #10 copper EGC would be appropriate.5.

Other Important Considerations



Disconnecting Means

You may need a disconnecting means in the outbuilding, depending on the specifics of the installation and your local codes. NEC 225.31 and 225.32 discuss disconnecting means for outbuildings. If your outbuilding has only one branch circuit, a disconnect may not be required. If there are multiple branch circuits, a disconnect is generally required. A simple 2-pole breaker in a small subpanel within the outbuilding would satisfy this requirement.

Grounding Electrode System

The outbuilding may require a grounding electrode system (ground rod(s) and grounding electrode conductor). Check NEC Article 250.32. If there are no other circuits in the outbuilding beyond the branch circuit you're running, you likely don't need a grounding electrode system at the outbuilding, provided you have a properly sized EGC run with the circuit conductors from the house panel.

Subpanel (Optional)

Consider installing a small subpanel in the outbuilding. This provides more flexibility for future expansion. If you do, follow all the proper grounding and bonding requirements for subpanels (separate neutral and ground bars, etc.).

Overcurrent Protection

Be sure to use the correct size circuit breakers (or fuses) at the house panel to protect the #10 conductors (20 amp max if using #12).

Wiring Method in the Outbuilding

Choose an appropriate wiring method inside the outbuilding (e.g., NM cable, EMT conduit, etc.) based on the environment and local codes.

Summary of Recommendations


Consult Local Electrical Inspector

This is absolutely critical. They have the final say.2.

Perform a Load Calculation

Determine the power needs of your outbuilding.3.

Pull the Required Permits

Don't skip this step.4.

Use #10 THHN/THWN copper conductors in the 2" PVC conduit. (or #12 for the 20A circuits)5.

Run a separate #10 copper equipment grounding conductor (EGC) with the circuit conductors.6.

Provide GFCI protection for all 120V, 15A and 20A receptacles in the outbuilding. GFCI breakers at the house panel or GFCI receptacles at the first outlet in the outbuilding on each circuit are good options.7.

Ensure proper grounding and bonding practices are followed throughout the installation.8.

Install a disconnecting means in the outbuilding if required by code. (Most likely).9.

Seal the conduit at both ends.10.

Consider a subpanel in the outbuilding for future flexibility.11.

Have the installation inspected before using it.

Disclaimer: This information is for general guidance only and is not a substitute for professional advice from a qualified electrician or electrical inspector. Electrical work can be dangerous, and you should only perform it if you are qualified and competent to do so. Incorrect wiring can cause fire, shock, and other hazards. Flag for review