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I have a 14.85 amp portable air dryer with a 20 amp plug - vertical/horizontal prong. Can i replace this plug to standard 15 amp both vertical prongs, and use safely on a 15 amp circuit? Assuming it will be used continuously for no more than 10 minutes?

I know about the 80% rule over 3 hours. But don't want to throw it out if it's reasonably safe.

Thanks for all the help. Not going to change it. I should have clarified that this is a animal blow dryer (dog). 10 kg. quite expensive.

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    Aside from the obvious fire hazard, odds are that the startup amps will trip the breaker every time you turn on the device.
    – MonkeyZeus
    Apr 14, 2020 at 12:35
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    I would maybe make an adapter cord and try it. If you can use it for a week without signs of trouble (tripped breaker, dryer sounding funny, etc) then it's probably OK to change the plug. (But it's extremely odd that such an ordinary household appliance came with a 20A plug, if it was intended to be marketed in the US.)
    – Hot Licks
    Apr 14, 2020 at 16:28
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    @MonkeyZeus That's more of a best case scenario. If the circuit is 20A with 15A plugs, the breaker will allow the device to pull 20A through that 15A plug.
    – JimmyJames
    Apr 14, 2020 at 16:29
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    @HotLicks Flames and/or visits from your local fire department should also be noted in such an experiment.
    – JimmyJames
    Apr 14, 2020 at 16:32
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    No. Never do this on anything with a plug. They select the plug size on purpose, and they're made to prevent you from putting them into holes they don't belong in. If you chop the plug off and put your own, you are wilfully insisting on doing what engineers have desperately tried to idiot-proof you into not doing. So don't.
    – J...
    Apr 14, 2020 at 16:33

3 Answers 3

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Of course you can't. The 20A plug was put there for a reason. Believe me, the manufacturer would much rather have put a 15A plug on there to make it more widely usable - they didn't use a 20A plug to annoy you... It's because they can't use a 15A.

The 80% rule also applies to portable appliances. No portable appliance using a NEMA 15A plug can draw more than 1500 watts (which is presumptive that the working voltage is 125V).

As George points out, modern bathroom receptacle circuits are supposed to be 20A. There's an exception in Code that allows you to put any common-as-dirt 15A duplex receptacle on 20A circuits; that's just so you only have to carry 1 receptacle on the truck instead of two (x 4 colors x normal/Decora; 8 is enough!) It also allows builders to use the 50 cent outlets instead of the $5 ones.

If your bathroom circuit is 20A breakered and wired with 12 AWG copper or 10 AWG aluminum wire, then you are at liberty to fit a 20A T-slot receptacle there.

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  • This is an excellent answer. I'd just add that changing the receptacle is going to take less time and be easier than changing the appliance cord and/or plug as well.
    – nexus_2006
    Apr 14, 2020 at 16:16
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    Great answer but "they didn't to annoy you" is awkward wording, though. I know what you mean but it sounds a bit like you are saying this was meant to annoy the OP.
    – JimmyJames
    Apr 14, 2020 at 16:36
  • @JimmyJames agreed, fixed.
    – Harper - Reinstate Monica
    Apr 14, 2020 at 18:05
  • "10 AWG aluminum " - Note that if you have aluminum wiring that you will need to use an aluminum rated outlet or make a copper pigtail using the correct copper-to-aluminum connectors. The aluminum-wiring tag covers this extensively and frequently, diy.stackexchange.com/questions/tagged/aluminum-wiring
    – Freiheit
    Apr 14, 2020 at 20:45
  • Also check the rating on the breaker?
    – spuck
    Apr 14, 2020 at 22:35
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I wouldn't do it. That hair dryer had that plug on it for a reason. Not only that, many 15 amp outlets/circuits use the horrible "back stab" outlets that do a lousy job handling that much current.

If you are using this in a bathroom that's relative modern, it should have a 20 amp circuit. If so and there are 15 amp outlets there now, you could swap in a true 20 amps outlet (GFCI if not protected in the panel) and you could use your hair dryer as is.

But don't change the plug. IMHO

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please DO NOT never go smaller for sure. best to use as the manufacturer states. and Im just guessing they would state its broke. get a new one! I personally would never advise tampering with electricity without having a good sense of how it all works. For thats very dangerous my friend.

Wondering why you just dont replace it for they are not expensive. And this is coming from me who is broker than most. :( But Im willing to help in getting you a working one thats safe to use if you would like. Please don't put yourself or others in a unsafe position. I had a dear friend die from getting electrocuted with using tore extension cord!! so let me know if you would like my further help.

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  • This clearly would not be dangerous . It would mean that the fuse would blow sooner in the event of a fault that caused it to draw more current (i.e. greater protection from fire etc. If anything, the risk of electric shock would be lower, but an ordinary fuse might not blow quickly enough to prevent that anyway.). It would just risk the fuse blowing when the appliance was (otherwise) working correctly.
    – John B. Lambe
    Apr 15, 2020 at 18:25

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