I found this receptacle installed and connected in an old work box with a regular receptacle plate in a U.S. house built in the early 1950s. It accepts up to four ungrounded, unpolarized plugs!

Does anyone know what these were called, and when and why they went out of production?

Ungrounded four-outlet plug from 1950s

  • 5
    A fire hazard would be my first guess at it's name. And why it stopped being produced. Commented Aug 13, 2018 at 21:11
  • Not just a fire hazard. But a huge shock hazard too. Commented Aug 13, 2018 at 21:53
  • 2
    please... Put a GFCI on it and don't worry another thought. Any modern NEMA 1 cord is now designed to interfere with superadjacent sockets like that, so you won't get more than 2 in it anyway. Largest I've seen is 5 in a row, in a Decora cover. Get some early 2-prong extension cords that are thin enough to 4-stack and use em for cell phone chargers etc. If NEMA 1 was that dangerous, they wouldn't make chainsaws that plug into it... Commented Aug 13, 2018 at 22:10
  • @Harper – Is "superadjacent" the common term for this? Was it popular at one time? (I actually did replace it with a GFCI, since this was the circuit's first stop, and no part of the circuit had a ground wire, but plenty of downstream receptacles have been retrofitted with grounded sockets, leaving open grounds.) It sounds like there's some interesting history around this, since (as you note) modern plugs seem to be overmolded ... specifically so they can't fit in this sort of socket?
    – feetwet
    Commented Aug 13, 2018 at 22:55
  • 2
    @TheEvilGreebo et. al.: Why is this inherently a fire hazard? Assuming it's on a 15A breaker and fed with at least 14-gauge copper?
    – feetwet
    Commented Aug 13, 2018 at 22:59

2 Answers 2


Ed didn't really seem to answer your question, other than the 'why' so I did some digging and found this a page that references the polarized version of the socket (see #5).

According to the page it is called:

4-plug socket


dates back to mid 1950s

Because the version in your picture probably when out of production just before the one linked (polarized one) came into production we can assume this is the end date of your particular yoke.

However, as Ed said, the last of the "4-plug socket" style yokes likely went out of production when the 3 prong grounding requirements came in.

As a side note: I've had experience trying to plug things into the Monolite Quintet socket, and found that even though it was designed for polarized plugs, one generally cannot plug two polarized plugs in next together at such a close proximity due to the fairly common skirt on the polarized plug. The "4-plug socket" seems to have similar spacing.


I have not seen those outlets in many years. I would believe the grounding requirement that came out after that time was the main reason you don't see them any longer although they were never common. The most I see now in line in a single yoke is 3 , there are 4 on a single yoke but these are in a square with the grounds at each edge and a space in the center.

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