Electrical – Help with sauna heater wiring diagram


Hoping to get some help understanding this sauna heater wiring diagram. Pics at bottom.

Disclaimer that I have an electrician friend "helping" (not for free though!) me on the weekends so I can't go too far wrong, but I am doing the runs and prep work to help the project go faster — and also just have an inquisitive mind toward learning and understanding all of this. That is just to say, don't be afraid to answer for educational purposes.

The unit consists of a wall-mounted controller (outside of sauna) and the heater itself + temperature sensor, inside the sauna.

The controller is supplied with 240v and contains the relay and PCB/controls to turn on the unit. Upon turning on the unit, obviously the heater is energized.

It's a 9KW heater. I have 6/3 with ground on a 50 amp breaker running to the sauna location.

It also has an option to power a 120v light (inside the sauna) from the controller, which I will not be taking advantage of.

My questions:

  1. Will I be using the neutral from the 220 run at all? (remember I am not going to use the 120v light option)

  2. I am generally confused about the jumpers on NN / LL for the power input, but only on NN for the output to the heater.

Generally, looking for confirmation on what goes where 🙂 Would appreciate if you could help demystify for me!


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Here are all 3 wiring diagrams supplied in the manual. I assumed the top one was relevant for me but perhaps not.

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Best Answer

The bottom drawing is for European 3-phase "wye" power with 3 legs of 240V and a neutral in the middle. All connections are made hot-neutral.

The top drawing is for European single-phase (aka 3-phase "wye" where your house is only provisioned with one of the phases). It has one leg of 240V and neutral.

The middle drawing is made for North America/Japan/Philippines "240V with neutral in the middle" (note the 60Hz assumption which is correct everywhere but southern Japan). Both hots have to be switched, so they change out to a much stronger single relay that switches both legs.

Not shown: the drawing to wire this up 208V/240V "delta", which you might do in New York City, Brazil or anywhere with wild-leg delta service. That wires up just like #3 except the 6 heater terminals are rearranged G U V U W W to put the 3 heating elements in a triangle (delta).

The reason for so many terminals is so they have the maximum flexibility to support a wide variety of configurations. In fact there is nowhere in the world you can't wire this. You only need to hook up 2 wires (other than ground) and also assure the relay is 2-pole and the heater jumpering is correct.

Do not continue if you see a 3-pole relay, you may think "extra pole, who cares" but the 2-pole relay handles larger amperage!

Keep in mind yellow/green is always ground (as is green or bare) worldwide.