Sauna heater power connection: What you need to pay attention!

Are you planning to purchase a home sauna? That's a good idea! However, extensive preparations are required.

These things should be considered when connecting a sauna heater

Your decision has been made to purchase a home sauna. You already know in which premises you will install it. You have also decided on the materials you want! Surely you have also discussed where and when you will buy the indoor sauna.

Your choice has fallen on an e-sauna. A smart decision, because this sauna is powered by electric current, so it is a clean thing. You do not need a permit from your chimney sweep for this “smoke-free” heating. This would be required if you were to operate your sauna heater with wood fire. A fireplace needs a mandatory smoke flue and is subject to other ordinances regulated by law. Instead, you must hire an electrical installer to install a power connection.

Have a power connection installed by a professional only

Please don’t get the idea of tinkering with the connection yourself! We like to believe that you’re a handyman in your spare time, yet when it comes to heavy current, it’s amateur electricians, hands off!
But why?
Because there are numerous regulations and requirements that must be taken into account! With electricity, the fun for leisure – craftsmen is over. You can’t see it, you can’t hear it, and you can’t smell it. When you feel it, in many cases it is too late. In the case of an apartment fire caused by improper installation of the sauna heater, the insurance company may deny the claim.

Know that:

  • A power cable with the designation H0 V V-F 5 x 2.5 must be installed?
  • The special cables for power connection are made of silicone?
  • “Normal” cables can become porous and brittle due to the influence of heat and moisture?
  • A power connection supplies 400 volts to operate the powerful sauna heater? A standard household outlet is rated at 230 volts.
  • 230 volts are sufficient for lighting and other electrical accessories of the sauna (radio/web modules)
  • Improper connection of the sauna heater including its control unit can cause a fire?
  • Your insurance will not cover a fire damage if the electrical connection is installed in a “do-it-yourself/DIY” way”? In any case, you will have difficulties in reimbursing the insurance premium!
  • A water pipe can be under current in relatively rare constellation?
  • An FI circuit breaker must be connected upstream to prevent short circuits?


What is a residual current circuit breaker?

F = fault, I = induction, simplified voltage.
Most of you know that this switch is present in the fuse box, but how it works is unknown. Here is a brief description:

Current flows into the switch, through it and out again. As soon as irregularities occur, the switch cuts off the power. A deviant measurement of the current occurs when the “juice” flows through one of your body parts, for example. The reason for the detour of the current path is usually a defective device or insulation. It can likewise be an overload of the home power grid.

Based on the detour, the current takes longer to flow back to the switch and then out. This incident is measured by the RCD because the otherwise zero values are registered as a deviation. The RCD reacts by interrupting the power supply. The RCD needs less than half a second for this life-saving measure.

Is it necessary to apply for a power connection?

Most household cook stoves with ovens also need heavy current. This is not simply plugging into the socket, but requires cable connections that are firmly clamped together. Three phases of 230 volts each are used, which are individually fused accordingly. Thus, it would be quite possible to connect the sauna heater to this connection. However, it is not advisable because of the fuse protection. The electrician who installs your connection also knows this. He will therefore refrain from doing so.

Interventions in the house electrics must always be agreed with the landlord. However, the landlord may not deny you a power connection without a good reason. Everyone needs to cook, so the power current for the stove/oven is usually available. Proceed in the same way with your electricity provider and register the power connection. Extract from the lease the agreements that are often disputed to be on the safe side.

The installation of a power connection by the possibly local electricity provider is usually considerably more expensive than that of a professional of your choice.


Sit down with your electrician of choice well in advance! This is ideally at a time before you set up the sauna!

Why is it important to appoint the electrician in advance?

The electrician will tell you specifically how he plans to proceed! He will list the materials needed if you want to do the purchasing yourself. You may save a few euros by doing so. Nevertheless, let the installer bring his own materials. He knows better than anyone else what is absolutely needed and what quality of material is required. You save yourself the tiresome walking.

He will discuss with you whether the supply lines are to be laid under plaster (in the case of longer cable runs), or superficially through a cable conduit. The cable is suitably routed through the ceiling of the sauna cabin to the socket for the power current. Therefore, the location of the socket for the power current will be in the upper part of the wall. Make sure that there is sufficient distance from the cabin wall to prevent heat accumulation.

The installation method is mainly based on the visual effect. If the walls of the sauna cover the power supply line, a cable conduit or channel that is not visible through the sauna paneling is sufficient.

Is it possible to make subsequent changes to the power supply?

Theoretically, you can do anything. But it does not make sense in this case, because subsequent work will be very time-consuming and unnecessarily expensive. This is true for almost all repairs or corrections to be made later.

What power does my sauna heater need?

Take the volume of the cabin from the construction manual of your sauna. Divide this by a factor of 1.5, and you will have the approximate power requirement.
Example: assumed 6 cubic meters of sauna volume divided by 1.5 = 3. Accordingly, you will need approximately 3 KW of heating power. Up to this size, the system can be called a “mini-sauna”, which can be operated with a standard household 230-volt socket. Higher heating capacities from about 3 KW need power current.

However, other values must be added, such as the location of the sauna (indoor or outdoor), as well as the insulation of the cabin. The power consumption depends mainly on the heating power to be provided by the sauna heater.

Keep in mind in all your considerations:

The sauna heater is the heart of the sauna

Without power no heater, without heater no heat, without heat no sauna.
On the subject of heat, we note the following:

  • If you use a heater that is too weak, the desired heat of 90° to 100° (194 to 212 °F)cannot be achieved.
  • You do not save any electricity with the small heater, because the heater is constantly busy to compensate for the decreasing temperature. Thus, it operates continuously and consumes a lot of electricity.
  • Therefore, it is important to consult a professional. The expert will calculate the standard values and create the optimal tuning in terms of heating power and power consumption.


Necessary heating power of a sauna heater

The size of the sauna room to be heated is also important. Not every heater is suitable for every room size. For your orientation, here is a small list of which heating power is suitable for which room size:

  • 4.5 kW for sauna cabins from 4 to 6 m³.
  • 6 kW for sauna cabins from 6 to 8 m³
  • 8 kW for sauna cabins from 7 to 13 m³
  • 9 kW for sauna cabins from 9 to 14 m³

For a reasonable sauna operation, the achievable temperature should be at least 80 °C (176 °F) , optimal temperature ranges are between 85 °C and 100 °C (185 to 212 °F) .


The perfectly adjusted heater of your sauna needs the most energy for heating up. After that, it maintains the achieved temperature for the entire period of use. You have had the power connection installed by a professional? Everything is set up and connected? Everything works as you want it to? Then nothing can stop you from enjoying your sauna!


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