Brushed brass steam shower valve and hand shower on white tile

November 3, 2026 Steam Shower Experts

Steam Generator Electrical Requirements: Amps, Wire and Breaker by Model

Short answer: every residential Mr. Steam and Kohler steam generator we sell runs on 240 volts and needs its own dedicated circuit. Small units draw about 13 to 27 amps; the largest home steam room units draw up to 125 amps. None of them plug into a normal 120V outlet. Your electrician sizes the breaker and wire from the generator's amps, and the tables below give those numbers for each model.

Is there a 120V steam shower generator?

Not among the residential generators we carry. Mr. Steam lists its residential generators at 240V single phase (208V and three-phase versions exist for some models), and Kohler's Invigoration generators are 240V only. A 120V circuit can't supply the 3 to 30 kilowatts these units need to heat water into steam fast enough for a shower. If a listing says "plug-in steam shower", it is usually a small portable unit or a cabin with its own built-in generator; check that cabin's spec sheet for its circuit.

Mr. Steam generators: amps and wire by model (240V, single phase)

Room size is the total adjusted volume after Mr. Steam's material and ceiling adjustments. Use our sizing calculator to get that number first.

Series	Model	kW	Adjusted room size	Amps at 240V	Min. copper wire	Typical breaker*
Steam@Home	SAH3000	3	60–75 cu ft (tile)	13 A	12 AWG	20 A
Steam@Home	SAH4500	4.5	76–110 cu ft	19 A	8 AWG	25 A
Steam@Home	SAH6000	6	111–150 cu ft	25 A	8 AWG	35 A
MS	MS90R	5	up to 71 cu ft	21 A	10 AWG	30 A
MS	MS150R	6	72–107 cu ft	25 A	8 AWG	35 A
MS	MS225R	7.5	108–161 cu ft	32 A	8 AWG	40 A
MS	MS400R	9	162–257 cu ft	38 A	8 AWG	50 A
Super	MSSuper1R	10	258–339 cu ft	42 A	8 AWG	60 A
Super	MSSuper2R	12	340–411 cu ft	50 A	6 AWG	70 A
Super	MSSuper3R	15	412–482 cu ft	63 A	4 AWG	80 A
MAX	MX4R	20	483–678 cu ft	84 A	2 AWG	110 A
MAX	MX5R	24	679–822 cu ft	100 A	1 AWG	125 A
MAX	MX6R	30	823–964 cu ft	125 A	2/0 AWG	175 A

*Mr. Steam's documents give amps and minimum wire size and say to install a separate circuit breaker between the supply and the unit. They do not print a breaker size. The breaker column is the typical circuit size used in distributor data; your electrician confirms it under your local code. At 208V the amps are higher (for example, Mr. Steam lists the MS90R at 24 A at 208V).

Kohler Invigoration generators: dedicated circuit by model (240V)

Model	kW	Max shower size	Rated amps	Dedicated circuit (Kohler)
K-32324-NA	5	84 cu ft	27 A	240V, 40 A
K-32325-NA	7	112 cu ft	36 A	240V, 50 A
K-32326-NA	9	240 cu ft	45 A	240V, 60 A
K-32327-NA	11	317 cu ft	46 A	240V, 60 A
K-32328-NA	13	447 cu ft	59 A	240V, 80 A
K-32329-NA	15	500 cu ft	68 A	240V, 90 A

Kohler prints the dedicated circuit in its installation instructions, so this column comes straight from the maker.

What your electrician needs to know

The exact model and voltage. Amps change with kW and with 208V vs 240V.
A dedicated circuit. The generator shares its circuit with nothing else.
Panel capacity. A 9 kW generator adds about 38 A of load; a MAX adds 84 to 125 A. Older 100 A panels may need a load calculation or an upgrade.
Distance from the panel. Long runs can need heavier wire than the minimum in the table.
Where the generator goes. Usually a vanity, closet, attic or basement near the shower, within the maker's maximum steam-line length. See our installation guide.
Permits. Many towns require an electrical permit for a new 240V circuit.

Does a steam generator need a GFCI breaker?

Follow the maker's installation instructions and your local code, and let your licensed electrician decide. Check the installation manual for your exact model before you buy a breaker.

How much power does a steam shower use?

The generator only draws full power while it is making steam. As a rough example, a 9 kW unit running for a 20-minute session uses up to about 3 kWh. At the October 2026 US average residential price of about 18 cents per kWh (EIA), that is roughly 50 cents a session at most. Your rate and session length will change this.

Quick answers

Can I run a steam generator on a 30 amp circuit?

Only the smallest models fit: Mr. Steam's MS90R (21 A, typically a 30 A circuit) and Steam@Home SAH3000 (13 A). Larger models need a bigger dedicated circuit.

Do I need a licensed electrician?

Yes. Both Mr. Steam and Kohler call for installation by qualified trades, and a new 240V circuit usually needs a permit.

Which generator size do I need?

That depends on your shower's volume and wall materials, not just its floor area. Use the sizing calculator, then match the model to the tables above.

Sources

Mr. Steam installation, operation and maintenance manual, MS90R–MS400R and MSSUPER1R–3R, PUR 100597A Rev 8.25.
Mr. Steam installation, operation and maintenance manual, MAX MX4R–MX6R, PUR 100598A Rev 8.25.
Mr. Steam installation, operation and maintenance manual, Steam@Home, PUR 100622 Rev 5.25; spec sheet TS0106 Rev 5.25.
Mr. Steam technical spec sheets TS0041 Rev 6.25 (MS) and TS0080 Rev 5.25 (MAX).
Kohler installation instructions, Steam Generator 5–11 kW, 1601844-2-B, and 13–15 kW, 1601845-2.
US Energy Information Administration, Short-Term Energy Outlook, October 2026, Table 7c.

How we write our guides: every number comes from the manufacturer's current manuals and spec sheets listed above. Updated November 2026.

Filed in: buying guide, electrical, steam showers

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