# Does it matter which way you plug stuff into the wall socket [closed]

I have a european socket and if you saw one you will know that you can plug stuff either way. But american sockets can only be plugged in only one way. So does it matter which way its plugged it because it works no matter what. I heard somewhere they use more power that way but i don't know if that's true

• If it mattered, I'd expect the plug to be designed so you couldn't plug it in the wrong way. Commented Oct 18, 2014 at 19:02
• possible duplicate of Why are some AC outlets and plugs polarized? Commented Oct 18, 2014 at 20:15

There are two ways to answer this.

No. Voltage is a relative measurement, and in any AC power system (American or European), one voltage oscillates above and then below the voltage of the other. Thus, from the perspective of the appliance, which has connections only to the two prongs of the outlet, it's impossible to tell one from the other, because the system is symmetrical.

simulate this circuit – Schematic created using CircuitLab

However, yes. There are things in the world besides those two prongs. For example, the Earth. In the US, an electrical outlet really looks something like this:

simulate this circuit

The connection between one half of the outlet and Earth is made near the electrical distribution panel:

Now consider, if someone should touch the half of the outlet connected to Earth, probably nothing bad will happen. However, if he should touch the other half of the outlet, he's likely to get shocked by completing the circuit through some accidental 2nd connection with Earth, or something else touching it (which is about everything).

So although flipping the plug around and inserting it backwards will probably be no problem with regard to the electrical operation of the appliance, it may create a safety hazard by exposing the "hot" half of the outlet, the half not connected to Earth, such that someone might touch it and be shocked.

National regulatory and licensing bodies have different requirements for an appliance to be certified as safe. In particular, the home's wiring can be backwards, or users can force plugs in backwards. Thus, things like double insulation have been developed to render appliances safe even in the presence of a fault like backwards home wiring.

• in that case i have to ask a question. When i push a test pen in one of the holes it light's up on the left side but doesn't on the right. Even if i plug in something and turn it on it still stays the same way (i torn down a wall socket to test this out). So basicly one is always powered and one isn't. I am afraid to touch them by hand tho Commented Oct 18, 2014 at 19:21
• @theraginggamer, see electronics.stackexchange.com/a/73137/17608 for some insight into how those devices work. They detect a changing voltage relative to their surroundings (Earth). They don't detect current. So, if you put it near the "neutral" half, there is no changing voltage relative to Earth, so it does not light up. Commented Oct 18, 2014 at 20:08
• @PhilFrost You in the US may have devices, which rely on proper orientation of live and neutral wires to be safe. However, european devices (which are usually connected to european wall outlets) do not. They have to work and be safe either way plugged in, even if they aren't doubly insulated. Commented Oct 18, 2014 at 20:27
• @theraginggamer: Yes you should be afraid to touch live wires, no matter what load is connected to them actually. And yes you should refrain from touching the apparent neutral wire, too. This is because your test pen may have fooled you. Those devices are rather error prone, because they rely on capacitive coupling to your surrounding, which may vary. Commented Oct 18, 2014 at 20:32

There is a pretty good answer here:

Why are some AC outlets and plugs polarized?