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Is there a way to plug a 6-20p 208/220/250v plug into a 10-30r receptacle? I can't seem to find an adapter for this. I bought a 220v fahrenheat heater and want to be able to plug it into a range or dryer receptacle.

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  • This application considers both ends of the issue at hand. Ultimately, the circuit breaker is intended to protect the house wiring, FIRST and foremost. If the device needed it's own in-line fuse or protection, step-down could be integrated. Here, the appliance would draw less than the breaker's maximum current. All will be cool, no pun intended.
    – Dad Bear
    Commented Oct 17, 2017 at 14:57

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You will not find a legal or listed "adapter" for this.

A 6-20 is a straight 240V grounding 20A device. A 10-30 is a 120/240V non-grounding 30A device, where the grounding function is provided via the neutral. This is only allowed in older range and dryer circuits, so any adapter would not be legal to use on any other circuit.

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    ...and you'd have a 30A breaker on a 20A device...
    – Ecnerwal
    Commented Feb 28, 2015 at 22:40
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    @Ecnerwal -- the ampacity is not the problem. A 6-20R to 14-30P adapter is legal; the equivalent with a 10-30P isn't because of the missing equipment grounding conductor. Besides -- how is a 20A heater on a circuit protected by a 30A breaker any different from a 1A clock radio on a circuit protected by a 15A breaker, or a 10A fridge with a 5-15P plugged into a 5-20T receptacle? Commented Mar 1, 2015 at 1:10
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NEMA 10-30 is still in use. I just bought a 16A 240V EV charger and had an outlet installed by a licensed electrician. When you try to interchange with a live ground you may or may not get into trouble. If the power is coming from the main panel (not a sub-panel), ground and neutral buses are shorted together. But if someone tried to do this where the power came from a sub-panel, then there would be no path to earth grounding for the 6-20 load. So actually what you want to do is invalid since neutral cannot be grounded; see this page for more details.

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Yes, there are actually adapters available for this. A quick web search for "6-20r to 10-30p adapter" should give you a few good results. Good luck! :)

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    These adapters cannot be legally used anywhere UL-listed wiring devices are required, as they cannot have a legit listing due to them abusing neutral as a ground, or leaving ground floating. Commented Feb 2, 2018 at 4:15
  • Using ground as neutral is unsafe, largely because the ground is not intended to be a current carrying conductor and might not even be insulated. However, using neutral as ground is not inherently unsafe. How do you think electric dryers plugging into a 10-30 outlet managed for all these years? Yes, they used the neutral for ground. Sure, the 10-30 doesn't meet current codes for new construction - but if you already have one, using an adapter to plug in an appliance with a 6-20 plug is perfectly safe. I'm an electrical engineer so I probably know a little bit about this stuff.
    – John R
    Commented Sep 11, 2019 at 1:51
  • The answer to the question re: NEMA 10 is "not very safely", that's how. The fact they're still in service today is an epic short-sightedness on the part of appliance manufacturers... Commented Sep 11, 2019 at 2:19

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