Does a sauna need a dedicated circuit?

An electric sauna heater should be the only thing on its circuit. Not because a code sentence says the word “sauna,” but because a 6kW heater at 240V draws 25 amps for hours at a time, the NEC sizes continuous loads at 125% of that draw, and 31.3 amps of a 35-amp circuit leaves nothing for anything else to share.

The code’s word for it is “individual”

Worth clearing up first, because it changes what you ask for. The NEC contains no formal definition of a “dedicated branch circuit.”It is the trade’s phrase, not the code’s. What the code defines, in Article 100, is an individual branch circuit: “a branch circuit that supplies only one utilization equipment.”

NEC 210.22 then sets the limit on it — an individual branch circuit “shall be permitted to supply any load for which it is rated, but in no case shall the load exceed the branch-circuit ampere rating.” So the requirement is not a special sauna rule. It is the ordinary consequence of a load that is large, continuous, and sized at 125%.

The arithmetic that settles it

Two facts do all the work. First, a sauna heater is a continuous load: Article 100 defines that as a load whose maximum current continues for three hours or more, and NEC 424.3(B) confirms fixed electric space-heating equipment is treated as one. Second, NEC 210.19(A)(1)(a) requires branch-circuit conductors to carry “not less than the noncontinuous load plus 125 percent of the continuous load.”

Multiply the draw by 1.25and round up to a standard breaker (NEC 240.6(A)) and you get the table below. Every figure is computed from rated kW at 240V — none of it is copied from a manufacturer, because almost none of them publish it.

Read the second column again. The smallest traditional heater on that list already draws more than a typical general-purpose circuit is rated for, and it does it for the whole session. There is no version of this where the heater politely shares.

Infrared draws less. It still wants its own circuit.

Infrared cabins are the low-draw end of this category, and they are the reason people ask whether the dedicated-circuit rule really applies. The Albott unit we compare is the only listing in our entire registry that publishes its own amperage: 2,850W at 240V and 20A. Twenty amps is a third of a big traditional heater — and it is still continuous, so 125% of it is 25A, and it still fills a circuit.

The distinction that actually matters is not dedicated-versus-shared. It is that infrared and traditional saunas are different machines, and they differ most visibly in the panel.

The question to ask before you buy, not after

“Does my panel have room?” is not the same question as “does my panel have two empty slots?” An 8kW heater wants a 50A breaker. On a 100A service that is half the nameplate capacity, and whether it genuinely fits depends on a load calculation across everything else in the house — the NEC Article 220 calculation your electrician runs, not a slot count.

This is the cheapest possible order of operations: price the circuit before you pick the heater. A 4.5kW heater that fits your existing service is a better sauna than a 9kW heater that needs a service upgrade you had not budgeted for. Our heater size calculator runs the volume-to-kW arithmetic and prints the circuit alongside it, so you can see the electrical consequence of the room you are planning.

What we are not telling you

We do not publish wire gauge, and we are not going to start here. Ampacity depends on conductor material, insulation temperature rating, ambient temperature, bundling and run length. A gauge table we cannot verify against primary code text for your installation is a safety claim we have no business making.

We are also deliberately not giving you a confident yes or no on GFCI. NEC 210.8(F) (2023) requires GFCI protection for outdoor outlets on single-phase branch circuits rated 150V-or-less to ground and 50A-or-less — which a 240V sauna circuit can fall inside — but the exceptions, and whether a hardwired heater is an “outlet” for this purpose, are genuinely debated among licensed electricians. That one goes to your AHJ.

We are not electricians, and this is not an electrical design service. Everything above is arithmetic on published ratings plus the code text we cite below. The installation is a licensed trade, and in most jurisdictions a new 240V circuit needs a permit.