Am installing a sauna and manufacturer says it needs 20 amp dedicated circuit or the warranty is voided.

My question is that since I already have 20 amp shared circuit, so long as I don’t plug anything else in that circuit is this okay ? The manufacturer says that is not okay but I’m doubtful about what they say. Seems to me they may not trust people when they say they won’t plug anything else into the circuit.

  • Does this sauna plug in or does it have to be hard wired? If it releases a lot of water to the surroundings, I would have it outside and not in the garage. Since I am not a professional electrician I can offer an opinion that if I wanted to I would use it on an existing non-dedicated circuit, but I would do some tests to verify the quality of the circuit. The circuit would have to be wired in 12 awg copper. You could check all the connections and insure they are made properly. Before or after that you could test the voltage drop under load at the receptacle you want to use. Aug 24 '20 at 15:47
  • If this is a good quality product, you will probably never have to make a warranty claim. But of course the mfgr probably knows that many people will not install a dedicated circuit and they can refuse warranty claims on that basis. Aug 24 '20 at 15:56

Code requires us to follow the MFG instructions per NEC 110.3.B .

Could there be issues using a circuit with multiple receptacles?

Possibly; additional splices or receptacles wired to code might create issues with devices that draw the maximum allowed amount if 1 screw or wirenut is not completely secure. This can create a high resistance connection where it may start arcing. Arcing can damage sensitive electronic components, so even without having anything else plugged in the multiple receptacles could be an issue, even if rare.

Because the instructions state it requires a dedicated circuit, a licensed electrician could not advise you otherwise.

  • Thanks for the info, I do have spare 20 amp line marked as spare in the electric pane but would have to run Romex to the sauna through attic then drop it down. The electrician is quoting me 800 to do it. Though since electric box is in garage if I put sauna in garage may be cheaper for him to run cable just in garage.
    – steviekm3
    Aug 24 '20 at 14:39
  • Sometimes the overall length doesn’t change the cost much. If you have good attic access. I know I charge more in the summer if I have to go in a attic. Depending on if your garage is finished or not (drywall walls and ceiling) there may not be a cost difference From where you would like to put it and your garage. the materials for a 20 amp circuit are not that high the difference being 20 or 30 less feet of Romex in most homes.
    – Ed Beal
    Aug 24 '20 at 14:51
  • Where would you like to install this sauna? Aug 24 '20 at 15:29
  • Well I was originally looking to put it outside, to do that setup will cost 800 from electrician but also I apparently have to buy cover for sauna from manufacturer which is 650. So now am think just put in garage to not need cover. The spare circuit runs from panel to attic to a what looks like sealed off junction box. Maybe I just take that apart and pull cable out and drop it down through garage. Box is right above garage in attic.
    – steviekm3
    Aug 24 '20 at 16:03
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    I know in my jurisdiction indoor tubs are required to have exhaust fans controlled by a humidistat.
    – Ed Beal
    Aug 24 '20 at 16:55

If you are serious about not plugging anything else into the existing 20 A circuit, you could disconnect the other receptacles, connect the wires with wire nuts, and put blank covers on the boxes. If there are no light switches on the circuit, then this would be a dedicated circuit.

EDIT But the only code approved, professional way to power this sauna would be to install a new dedicated circuit for the sauna. You might get more estimates. If you did convert the circuit to "dedicated" you might have to replace the duplex receptacle with a single.

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    Jim that would have the splice issue still yes it would be dedicated. Next if those receptacles are in rooms or locations that requires them removal would be a direct code violation.
    – Ed Beal
    Aug 24 '20 at 16:54
  • The poster says in a comment that he has a cable in the attic connected to a 20 A breaker. It should not cost anywhere near $800 to take this to an outside dedicated receptacle where he wants to install the sauna. His wording to just pull it down into the garage suggests he should have it done professionally rather than DIYin' the job. Aug 24 '20 at 22:47
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    Jim as you know $ are off topic but I won’t change a light switch for under 150.00 and thats when I have the time to do it. The permit Cost materials and time all add up this might be able to be done in an hour or it could take 3-4 hours you have no way to judge a cost on a job that you haven’t looked at.
    – Ed Beal
    Aug 24 '20 at 22:49

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