As mentioned in this video here, many country and lakeside saunas don’t have electricity.
In Finland and everywhere, many traditional saunas were built before electricity. Also, many saunas are built away from the main house, cabin, cottage. To the positive, this reality is what helps make the sauna building a true escape, a step back in time and towards simplicity.
There is a wind of change: solar and wind systems are becoming more affordable for the average bear.
Saunas that have been lit exclusively by candle or lantern may now, with the flick of a switch, be powered up like the LM in Apollo 13.
When building an outdoor sauna, spend the extra time and cash to wire the structure for lights and outlets.
A simple hot room light, a couple wall sconses in changing room, and an outdoor patio light is all is needed (the power of three). Oh, and put ’em all on dimmers. One can bring power into the structure by wiring an RV electrical plug (expensive) or a simple male plug tucked under the structure outside. The system can be tested and powered for sauna parties by running extension cord from nearest power source.
Run 12/2 wire from the outside plug under the bottom plate directly to a GFI outlet, then run power to lights and additional outlet(s). This keeps your entire system safe from power surges and accidents eg. when a drunken guest thinks your triple light switch is a sink.
When you step up to get the solar panel or wind turbine, your structure is wired and ready to go.