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How to Wire Your Sauna Heater

Follow these general guidelines and tips when wiring your Polar sauna heater

NOTE: When installing your sauna heater ALWAYS hire a licensed electrician,
so you know your installation was done according to your local electrical codes,
and ALWAYS check your POWER is OFF before starting any electrical work

We sell a DIY precut home sauna kits (sometimes callled "liner kits") if you're converting a room into a sauna.  If you have your own lumber then of course, use it up and cut and build your own. Indoor saunas require lowering the ceiling. If you prefer, not to lower your ceiling height. Then, consider the DIY prefab modular sauna kits. These kits use 6'8" wall panels, and are often placed in a larger room, basement, cabin or sometimes under an outside shelter. Also see how to measure and order a precut sauna. If we can be of more help, please email us or call us at 1.800.426.3929 or read on. Thanks!


How to Wire Your Sauna Heater —  Click on each pic to enlarge and read the caption

Conduit to sauna ceiling running 8-3 and 12-3 (or 12-4) wires 8-3 and 12-3 (or 12-4) wires coming sauna ceiling Wires to the sauna control panel plus thermostat wire Sauna control panel wired to run the heater and outside light Sauna PSC-9 control panel Polar HNVR 80 Sauna heater wires connections Sauna heater wires labeled at bottom Sauna wired and mounted on the wall (with humidifier insert)
Supplies You'll Need to Wire Your Sauna Heater:
  • Polar HNVR 80 sauna heater
  • PSC-9 control panel
  • 8-3 electrical wire
  • 12-3 (or 12-4) electrical wire
  • 12-5 electrical wire
  • 18-2 thermostat wire and thermostat (incl. with the PSC-9)
  • Two 40 amp breaker panels
  • One or two 20 amp breakers
  • 1½" Schedule 80 and 40 pipe conduit (if outdoors)
  • 1" Rubber wall conduit (optional)


Prior to building your sauna room, scan our planning your sauna pages and the sauna venting and framing article.

How to Wire Your Sauna Heater: Intro

Most sauna heaters (at least any with real power) require an 8-3 wire, and 12-3 wire to power the control panel light switch and any other lights and wall outlets.

The 8-3 wire (meaning 8 gauge with 3 wires: hot or load, neutral and a ground wire) runs from the control panel directly to the heater through the ceiling or through the wall.

In this case, we are controling the Polar HNVR 80 sauna heater thru a PSC-9 Control panel which requires power for the indoor (or outside) light.

Wire your room for a light, light switch, sauna heater wire conduit, and perhaps controls outside the room. If preparing for a gas sauna heater, then you're using gas pipe and you'll have to consider the thickness of the pipe and how many other appliances share the gas line. Consult your gas professional.

Run the 8-3 Wire: From the Control Panel Directly to the Sauna Heater

We plan our sauna kits so that all power is run to the celing first and then from there you can easily thread wires through rubber conduits pre-installed in the sauna panels to your heater, control panel, switches and outlets.

  • IF you are erecting a freestanding outdoor sauna, you will run your wire underground in Schedule 80 (ground-rated) electrical pipe conduit.
  • IF you are building an indoor sauna, then you can run your wire through your studs directly to the heater using the most direct route to your sauna heater.

In both cases, the 8-3 wire runs uninterrupted from a double 40 amp breaker in the control panel to the underside of the sauna heater. Always run your wire while NOT connected to your house's electrical control panel.

Each sauna heater comes with specific instructions for a variety of control panels. Simple sauna heaters have the control panel on the bottom front of the unit, e.g. the Polar HMR series. Generally there are 6 available connector poles to accommodate all wiring arrangements for 8-3 wire: two hot (or load) wires are connected to poles #2 and #4, neutral and ground. Next run your control panel wiring.

Wiring the Control Panel: Connecting to the Sauna Heater

I was a bit surprised by this warning tag in the box, "Warning: This Heater Does NOT Work" but quickly realized the manufacturer wants to get your attention regarding the PSC-9 control panel's functionality which basically requires that you turn the dial to about 3 o'clock and then back to 1 o'clock until you hear a click. This starts the heater immediately otherwise you're delaying the start time per the timer.

It's easiest to wire complete your wiring while the sauna heater is on it's back, so attach your heater to the wall just to measure the wire lengths needed. I found a milk crate to be the perfect height.

Quick steps:

  1. Once you've centered the heater on the wall you can measure the wire lengths needed.
  2. Run 12-5 wire from the control panel to the bottom of the sauna heater
  3. Connect the numbered wires #10, #11 and #12, neutral and ground in the sauna control box first, then make connects the heater's junction box
  4. Now remove the heater and lay it on a milk crate (or something of similar height) to make the connections on the underside of the heater

Start by removing the front and bottom covers of the sauna heater. While we have the sauna heater exposed notice there are two switches to reset fuses inside the sauna heater.

  • One protects the control panel from any electrical shorts. It's a narrow switch nearest the wiring box.
  • The other is a low round button which protects the heater from over-heating. It makes an audible click when reset. This sits under a small hole in the bottom cover, but large enough to insert a pen or a screwdriver and reset the heater

The gang box for the sauna heater is a tight area so you will want to measure your wire length well but keep a little extra. In the case of the PSC-9 Control Panel and many control panels, they get their power directly from the sauna heater. This control panel has both an ON/OFF switch, a timer with a 9 hr count down and a thermostat, so it requires a short length of 12-5 wire as well as the 18-2 thermostat wire.

Start by deciding where to put your control panel – typically near the door and outside the sauna and ideally near your sauna heater. The PSC-9 comes with a housing that acts as the gang box. We recommend using 1" rubber conduit to house your wire for its insulative qualities and it's easier to thread wire thru the sauna panels. Set the housing in the wall and run your 12-5 wire through rubber conduit in the interior wall or sauna panel between the heater and the control panel area.

If using the conduit, leave about 2' of rubber conduit coming out of the wall below the sauna heater. This will house only the 12 gauge wire not the 8 gauge wire. The wires in the control panel are nicely numbered $10, #11, #12, neutral and a ground wire, thus the need for 12-5. These match the receiving poles held by screws in the bottom of the Polar HNVR 80 sauna heater.

TIP: Water ladeled onto the sauna rocks for steam can fall to the bottom and some may get into the rubber conduit, so we recommend cutting a slot at the bottom of the bend to allow any excess water to escape.

The PSC-9 does have a switch to either control and indoor or outside light which is powered by a separate 20 amp circuit, as are any lights, switches and wall.

We recommend running all power through the ceiling, thus in our set-up the 12 gauge wire ran to a large junction box in the ceiling, then wires ran to the control panel light switch for the outdoor light, a switch for interior light, a switch to power the interior floor outlet and power to a salt lamp.

See How to Build Your Sauna: Mounting the Sauna Heater on the Wall

See our text and videos regarding mounting your sauna heater on our How to Build a Sauna | Converting a Room to a Sauna article.

And before you turn your heater on consider our array of sauna accessories: sauna wool hats, sauna heater humidifier, and much more.

ENJOY! There are some good sauna accessories to help you relax, such as head and leg rests, duckboard (flooring for the walkway), salt lamps, thermometers, hygrometers (to measure humidity), venik (to brush the body) ... enjoy!

Also read Home Sauna Room Advantages — Reviews the advantages of having a sauna in your home, such as cost, comfort, privacy, and convenience.

If we can be of more help, please email us or call us at 1.800.426.3929 or read on. Thanks!


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