Saunas and Home Sauna Kits FAQs
Interior lighting without the conduit made ready
Wiring your sauna without the conduit
Interior lighting could be wired by your electrician, who would use a tool called a fish tape, to feed wire through the inside of the panel. In some cases, you could certainly run your light wire up the outside wall in a conduit, and then bore a hole straight through the wall to the other side and place your light on the inside rather than the ceiling. See some sauna conduit photos here.
The other option is to remove the tongue'n'groove wood and run wiring through the wall, then replace them. The conduit is really for ease of installation, not to protect the wires from heat.
Some sauna bathers use a lantern, candles on the floor and some just prefer the flame of the wood-fired sauna heater. See some sauna lighting choices. Enjoy!