The NEMA 10-20R Crow's Foot Receptacle

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CoolWill

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Location
Alabama
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Electrical Contractor
I've seen them used for wall and window air conditioners. I've seen them on large electric space heaters. They are still sold in Ace Hardware and online. But I don't know how they were legal even in the time periods they were used. Even in the 1968 NEC, only dryers and ranges could be bonded to the neutral for grounding purposes. Window A/C units could be ungrounded if certain conditions were met, but it seems exceeding unlikely that any of the ones I've encountered met those conditions. The pic I attached is a screenshot of the 1968 NEC concerning grounding window A/C units. So where were these receptacles legal?Screenshot_20240512-082942~2.png
 
Yes and No.

Kind of nothing wrong with using the neutral terminal of those as an EGC, but keep in mind that it is not bonded to the yoke of the device so you can't depend on yoke contact with the box for continuity of the EGC.

Is it violation of not following listing/instructions - probably.

ADD: I have to admit there is a lot of 10-50 receptacles used around here that really should be 6-50. They are not using a neutral conductor so not too big of a deal, until someone comes up with something that does have a neutral and plugs into it, though that is also pretty rare other than for an electric range.
 
They are still used in Australia and New Zealand as the general daily outlet. The center pin is EGC. I suspect that is what was happening with air conditioners back in the day as well. I lived in a house that had one and actually used it for a time, not that many years ago. There was nothing 120V inside the AC. It had to have been EGC although I never investigated.
 
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