Switch and electrical outlet

[Lerxst]

Trying to figure out why this outlet and switch were wired this way. One of the blacks to the switch is the hot. The other black is unswitched and goes to an outlet. The red wire is switched and goes to the outlet pictured.

I was able to figure out and successfully replace the switch (although I'm still unsure where the hot is coming from), but I don't understand 2 whites at the outlet.

 

[Reach4]

With a voltmeter, check to see if either of the two whites has line voltage on it with respect to the bare wire.

 

[Sponsor]

 

[Lerxst]

With a voltmeter, check to see if either of the two whites has line voltage on it with respect to the bare wire.

Not sure what you mean by "with respect to the bare wire."

I plugged one of those outlet testers into the outlet and lights indicate it's correct.

 

[Reach4]

Not sure what you mean by "with respect to the bare wire."

That means to put one meter probe on the bare wire, and the other on the copper or screw of each white wire. So instead of "with respect to", I should have said between each white and the bare wire. I am suspecting that at some point not shown in either of the two photos, somebody connected one of the whites (probably the one farthest from the other wires) to an always-hot wire without marking the white wire appropriately.

On a different but related note, if there is no screw, those are "backstab" switches and receptacles. I would be tempted to replace them, but it is not necessary. For reading on the topic, I suggest searching for backstab wires in your favorite search engine.

 

[Jadnashua]

It appears that the two black wires at the switch are connected to the same contact. If so, that connection is being used as a feed-through to that other outlet providing power there. The power to the one receptacle with the red wire on it is being switched by the wall switch. Many people like one half to be constant on, and the other to be switched, and if the two black wires are also in that box, it would be easy to make that happen. So, what you have is one receptacle that is switched by the wall switch, and a second (and maybe more) that get their power because those two black wires are tied together in a daisy chain.

 

[ActionDave]

It's a switched outlet. You can turn on a lamp when you come into the room, the other half of the plug stays hot all the time so you can plug something in that you don't want turned off with the switch.

 

[hj]

The two white wires are feeding through to another receptacle

 

[Jadnashua]

BOth halves of that receptacle are switched. If you want one part to be constantly on, break the tab on the side where the red wire is attached to separate them, and then add a jumper from the blacks in the back of the electrical box to the now separated half.

 

[hj]

IF there are black wires in the rear of the receptacle box, they are very short or neatly coiled because I cannot see any.

 

[Jadnashua]

With two whites and a red, it would be tough to not have the black wires in there somewhere!

 

[Lerxst]

Turns out the black wires were tucked neatly in the back of the box and covered with 50 years of dust making them nearly impossible to see. I was able to split the receptacle and have one outlet switched and the other always on.

Thanks for all the tips!