This looks like an outlet with only one receptacle, but why?

It's mounted about 7' up, in a basement-level room in a school building. It is stamped 15A/125V, but I've never seen something like this before.

My question is, is it indeed a standard (US) 120vac outlet, can I plug regular things into it, and why does it look so strange/why does it only have one receptacle? Also, what's that little hooky thing for at the top?

enter image description here

1 Answer 1


It's for a plug in clock. You hang the clock on the little hook, and the receptacle is backset so the plug does not interfere with the clock sitting flush against the wall.

  • 4
    It’s a regular outlet that will handle 15amps. There’s just one because it’s specifically made for a clock, but it’s electrically the same as any other outlet.
    – JPhi1618
    Commented Oct 7, 2021 at 2:28
  • 24
    And it may be (or have been) on a dedicated clock circuit. For those not old enough to remember before quartz clocks (much less cell phones), clocks in a school need to be kept synchronous so all the classes end at the same time to give kids time to move to the next. A dedicated clock circuit, with appropriate clocks, does this with current pulses on the clock circuit to reset the hands of all the clocks on the circuit to the same position. You would hear a loud buzzing noise, and the minute/hour hands would move. Usually done first thing in the morning.
    – Jon Custer
    Commented Oct 7, 2021 at 13:46
  • 1
    If it's in the US, @DarrelHoffman, and it appears to be, a 15A circuit is the smallest we generally go. I think there may be some 10A breakers, but they're pretty rare and would only be used for very specific items, and probably don't have a NEMA 5-15 outlet. Also, see Jon Custer's comment - could have been a lot of clocks on this one 15A circuit. A whole school full might have drawn a solid 6-10A! :)
    – FreeMan
    Commented Oct 7, 2021 at 18:16
  • 5
    @JonCuster makes a good point. If this outlet was fed by a clock synchronizer intended for schools, you may not be able to use it for other things. It would be interesting if you provide an update! For comparison the same kind of outlet is found above the kitchen sink in a lot of US homes built between about 1930 and 1980.
    – jay613
    Commented Oct 7, 2021 at 19:03
  • 14
    Some local codes used to specify (or perhaps still do) that in residential kitchens, a clock outlet would share the circuit with the fridge, so you could tell by how late the clock was, how long your fridge had been without power.
    – CCTO
    Commented Oct 7, 2021 at 19:08

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