It is my understanding that the following photo contains a phone jack (old style 4 prong) to the left and a standard nema-15r outlet to the right.

Photo of what i thought was an old phone jack

Well, we had found some mold in our basement under some old wood paneling and when I removed the old Sheetrock I noticed Romex (that is live) going into the box. My question is, what would be the purpose of this? Obviously, i'm going to cut power at the breaker and remove this... but why would someone do this in the first place? Is this not a phone jack as I'd assumed?

enter image description here

  • Show us the other side. What happens in the box? My guess is that it was just used for a junction/passthrough.
    – isherwood
    Mar 17, 2018 at 16:25
  • I'm not messing with it this moment, but yeah it might be just a passthrough - just weird to me since there is another junction 12" away (in the bottom picture the source is on the right).
    – Robin
    Mar 17, 2018 at 16:45
  • I would be with the others who suspect that it was a horrible hack by someone who didn't have the wirenuts needed to make a legitimate splice in the box.
    – Hot Licks
    Mar 17, 2018 at 21:32

2 Answers 2


From your back side picture it is apparent that no small gauge low voltage wiring goes to the box with the four prong plug. So unlikely that the plug was used for wired phone service at any time in the near history.

It is almost sure that someone at one time wanted to power some ill conceived device with power through a four prong plug. If you open up that box you will undoubtedly find that some pins on that plug are wired into the power circuit that passes through that electrical box.

Sometimes it is just hard to understand some of the schemes that folks will dream up and cobble together, whether it is safe or not.

  • I think you might be right, pulling the jack out slightly there are wires connected to it... The new romex and the blue old construction box i put in to get an outlet in the garage for our deep freezer. Had i known they used the "phone box" as a junction it would have made my job a lot easier a few years ago... Now i just get to fix it rolls eyes
    – Robin
    Mar 17, 2018 at 16:56
  • 3
    eek... yeah, somebody jury rigged something, or they got a Princess phone and really didn't understand how the dial light worked. (6-8V). Or possibly there's a tiny Princess phone transformer crammed in there. Kill it with fire before it kills you with fire. Mar 17, 2018 at 19:42

Here's what happened

Originally the phone box was a power receptacle and the blue box wasn't there.

Look at the short run of old Romex between the phone box and the blue box. That run used to go all the way to the other steel box, but the cable had a problem. So the last guy cut a hole for access and installed the blue box as a splice point. (keep in mind the drywall was installed; he was reaching through.)

Why he moved the socket to the blue box and put a phone box in the old location - I have no idea. It is illegal to put a phone jack there.

Fix it the way they intended

They gave you enough length in the new Romex for the metal boxes to connect to each other - they just didn't have the access to complete the job. I would convert the "phone" box back to a receptacle box, and deprecate the blue old-work box, as the way it's mounted is a compromise and not particularly strong.

  • Open up the blue box and remove all wires from it, being careful to remove the newer Romex intact (the short old Romex can just be cut).
  • Open up the phone box, remove the phone socket, and finish removing the short old Romex and throw it away.
  • Into its hole goes the newer Romex.
  • Install a power receptacle where the phone jack had been.
  • On the blue box, fit a blank cover plate or convert it to comms use (cable TV, ethernet, phone etc.)

Now the two metal boxes are your receptacle boxes again. They are properly anchored to the joist, so if you are wrestling a stiff plug, there's no worries of tearing the box out of the drywall. Metal boxes don't burn or melt, and can be grounded.

If the wiring is not already grounded, now is the time to retrofit grounds to all the boxes (except the blue one obviously.) In 2014 they greatly relaxed the rules on retrofitting grounds.

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