So I sometimes hear that the outlet has a smaller hole for hot and larger for cold so its harder to stick your finger in hot. But if it is an AC wave, shouldn't they both be the same, because they get 50% of pos. and neg? What exactly does Hot and Cold mean on an AC outlet and does it have something to do with ground? (ex: you touch hot and it goes through your body to ground and gives you a shock)
Electronic – What does hot and cold mean on an AC outlet
outlet
Related Solutions
The normal (if a bit optimistic) values you'd be looking for are 120V Hot->Neutral, 120V Hot->GND, and 0V Neutral->GND. It sounds like you pretty much get that already.
I'd be strongly inclined to believe the fault is not in the socket itself, but rather either in a connected appliance or in the wiring itself. The wiring TO the socket could be at fault, especially in a socket that had been habitually overloaded (and heated up as a result).
You might start by unplugging everything in your apartment and testing again. If that clears the fault, plug half of them back in, see if it reoccurs, then step-wise in that binary fashion narrow it down to a single appliance.
If that doesn't clear the fault, I would head to the breaker box and take measurements with your circuit's breaker in the OFF position. But this is probably where you should start looking for someone like an electrician, because this gets you into the (more) dangerous zone, likely having to remove the cover plate from the breaker box. But a measurement here would show whether the fault is inside or outside your apartment.
If you don't mind using a power cord, I highly recommend using a PCB-mount IEC connector instead. These are very common and readily available.
If you absolutely must have a device that plugs directly into the wall, I recommend building your Wifi extender into an enclosure with an integrated mains plug:
Individual PCB-mount mains contacts do exist, but are fairly uncommon and difficult to source. I recommend using one of the above options instead.
EDIT: It looks like Heyco (a company owned by PennEngineering) makes PCB-mount mains blades:
https://www.heyco.com/Power_Components/pdf/PCB-Contacts.pdf
Best Answer
In the USA
One thing that the other answers did not cover, the line coming in to your house is actually 3 lines from a transformer with a center tap. That center tap is the "cold" and the two ends are both "hot", to get 120 you go from the center to one of the ends and to get 240 you go from end to end
In your breaker box it alternates which end is available each line, that is why 240 breakers are two wide, it is connecting the two ends together instead of the middle and the end.
In Europe
Similar principles apply with the following major differences