I just moved into a very old apartment. There is only one plug in the dining room and it is very strange. It takes four same-sized vertical prongs, similar to a 50 amp outlet except the bottom is also vertical.

Picture of weird outlet

Some regular 3 prong plugs will fit in and our landlord insists that she has used it this way before with no issues. The problem is we want to plug in our mini fridge there and it doesn't fit (the ground prong is too wide). I tried using a 2-3 prong adapter but the ground part of the adapter ends up at the top or bottom and not by the screw, and I am just not comfortable plugging a fridge into a non-grounded outlet.

Does anyone know how we can convert this type of outlet to the traditional 3 prong grounded outlet so I can plug in my fridge? Sadly since we are renting we can't do any electrical work to accomplish this goal.

  • The screw may not be grounded anyway. Commented Jun 30, 2014 at 12:07

2 Answers 2


This is an obsolete socket type called a parallel and tandem socket, and is designed to accept either standard parallel plugs without a ground or older tandem style plugs (again without a ground):

enter image description here

None of the connections is a ground - it consists of 2 pairs of hot and neutrals, one oriented vertically, the other horizontally. If there is a ground wire to the box (which I doubt), this can be replaced with a standard 3 prong outlet. If not, you'd have to find a way to get a ground into the box.

  • 5
    If getting a ground to the box is not easily doable, the next best thing is to replace it with a GFCI
    – Steven
    Commented Jun 30, 2014 at 0:05

I would quietly take it out and replace it with a new standard electrical outlet which might set you back $1—and probably leave it when I move away. If there is serious enforcement of not changing wiring, then go ahead and put the original back when you move.

There probably is no ground connection and adding one will be difficult (i.e. expensive). Running it without a ground connection is not considered safe by modern standards, but it is how it used to be done, though some care was often taken to bond the neutral to the case.

  • 2
    The problem with using neutral in place of ground is if the you get a bad neutral connection, you end up with the device's case hot! That's why it's no longer allowed.
    – DoxyLover
    Commented Jun 30, 2014 at 18:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.