Okay, let's break this down and look at the relevant code sections and calculations. You're on the right track, but we need to ensure everything is compliant.

Summary of your plan



Exterior Subpanel

Supplying a sauna, lighting, and receptacle.

Sauna

10.5 kW, intended to be on a 50A breaker.

Lights/Receptacle

15A breaker.

Feeder

3/4" EMT with #6 THWN (2 hots, 1 neutral), #10 ground. Protected by a 60A breaker in the main panel.

Sauna Load Calculation

43.75A

Code Considerations and Analysis


Load Calculation for Sauna

You calculated the sauna load as 10,500W / 240V = 43.75A. This is correct.
2.

Feeder Conductor Ampacity

#6 THWN is typically rated for at least 55 amps in the 75°C column (check your specific THWN conductor's ampacity rating). Since you're using a 60A breaker, your #6 conductors could be overloaded. NEC 240.4(B) allows you to go to the next standard overcurrent device rating if the conductor ampacity does not correspond with the standard overcurrent device rating. In this instance, if your #6 conductors are rated at 55 amps, you can use a 60 amp breaker.
3.

Subpanel Size and Main Breaker

Your feeder is protected by a 60A breaker in the main panel. The sum of your connected loads is 43.75A (sauna) + 15A (lights/receptacle) = 58.75A. Your calculation is missing the 125% rule for continuous loads. It is unlikely that your general use receptacle would be considered a continuous load, and the LED lights will only draw a small amount of power. The sauna is likely considered a continuous load, therefore the feeder would need to be sized for 43.75 1.25 = 54.
68. 54.68 amps + 15amps (lights/receptacle) is 69.68 amps. Therefore you will need to upsize your feeder conductors.4.

Grounding Conductor

#10 AWG copper is adequate for grounding a 60A circuit (NEC 250.122).
5.

EMT Conduit Size

3/4" EMT is sufficient for the conductors you listed.6.

Subpanel Main Breaker/Lugs

The subpanel must have a main breaker or main lugs rated appropriately. If the panel uses a main breaker, it should be rated at least 60A.7.

Overcurrent Protection for Sauna

Your plan is to use a 50A breaker for the sauna. This appears acceptable, as your calculated sauna load is 43.75A. The breaker should be sized to protect the sauna equipment.
8.

Overcurrent Protection for Lights/Receptacle

A 15A breaker is appropriate for a general-use lighting and receptacle circuit using #14 AWG conductors (check conductor ampacity).

Recommendations



Upgrade Feeder Conductors

Consider using #4 THWN conductors. This should give you an ampacity of 70amps, which will satisfy the 125% rule for the sauna load.

Confirm THWN Ampacity

Double-check the ampacity of the specific THWN conductors you are using in the 75°C column.

Local Codes

Always check with your local electrical inspector or building department for any local amendments or specific requirements.

Continuous Load Assessment

Carefully consider if any loads on the 15A circuit could be considered continuous (operate for 3 hours or more at a time). If so, apply the 125% rule to that load as well.

Revised Plan Summary



Exterior Subpanel

Supplying a sauna, lighting, and receptacle.

Sauna

10.5 kW, intended to be on a 50A breaker.

Lights/Receptacle

15A breaker.

Feeder

3/4" EMT with #4 THWN (2 hots, 1 neutral), #10 ground. Protected by a 60A breaker in the main panel.

Sauna Load Calculation

43.75A

Disclaimer: I am an AI Chatbot. This information is for guidance only and should not be considered a substitute for the advice of a qualified electrician. Electrical work can be dangerous and should only be performed by qualified professionals. Always consult with a licensed electrician for your specific situation. Flag for review