Electrical – GFCI outlet hot when nothing’s plugged into it

electricalgfcireceptacle

Using a thermal camera (coolest thing in the world, by the way), I discovered that a GFCI outlet in my bathroom is hotter then the surrounding wall when nothing's plugged into it:

enter image description here

It's not boiling hot; just slightly warm to the touch. I never noticed it before I had a thermal camera. This is probably bad, but what does it mean? Should I replace it? Is my house about to burn down?

Update to answer several people's questions:

  • The GFCI is on an interior wall covered with cementboard.
  • The wiring is copper.
  • All other non-GFCI electrical receptacles–including those on exterior walls–are any different from the surrounding wall in terms of temperature. Here's one on an exterior wall: enter image description here
  • I don't believe there are any downstream connections.
  • The heat is emanating from the right side of the unit itself: enter image description here
  • The box is quite small; the sides of the GFCI are about 4mm away from the sides of the box. Not a lot of room for it to dissipate heat.

Best Answer

As mentioned in several places, GFCIs use a little bit of power even when nothing is plugged in or energized downstream.

The heat distribution sure looks like it is coming from the GFCI electronics, but it could also be heat seeping from the other side of the wall, especially if that room has higher air pressure than this one—like if the exhaust fan were running in this room and someone took a hot shower in the other room. Presumably there is another outlet on the other side of the wall close to this one.

You could try turning off this circuit for 15–30 minutes and see if it completely cools. That would also rule out whether there is anything downstream causing a current to flow through it.

Or you could measure its power consumption and see if it is more than 100 mW or so. If it is more than 1.0 watts, I'd replace it.

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