What exactly is the difference between a 110v and a 220v labeled power outlet?

As far as I can see, the outlet is just a piece of plastic with some metal connecting to the power cables. Both types of outlets seem to be identically built.

Does it pose a problem to mount a 110v power outlet on a 220v power cable?

To clarify, the plugged in devices are using 220v as the power system provides, the question is really just about the power outlet itself.


migrated from physics.stackexchange.com Nov 14 '16 at 15:54

This question came from our site for active researchers, academics and students of physics.

  • \$\begingroup\$ Would Electrical Engineering be a better home for this question? \$\endgroup\$ – Qmechanic Nov 11 '16 at 13:51
  • \$\begingroup\$ I suggested DIY, but I just have to discourage the idea of wiring a 110V outlet with 220V. \$\endgroup\$ – Mike Nov 11 '16 at 13:55
  • \$\begingroup\$ It is not the plug or the wire, it is the device, which requires the specified voltage... Two plugs looking equal doesn't say anything - the circuits of their devices might be different. \$\endgroup\$ – Steeven Nov 11 '16 at 16:47
  • \$\begingroup\$ @Steeven Two plugs or outlets looking equal are not necessarily equal - subtle differences in their inner design can have impact. \$\endgroup\$ – sharptooth Feb 1 at 16:02

Get the right outlet, so the device-frying dunderhead isn't you!

The difference between a 110V (NEMA 1 or NEMA 5) and a 220V (NEMA 6) outlet is in the arrangement of the contacts. Most 110V outlets can survive 220V across them (and are sometimes expected to in normal operation i.e. when the two outlets are on opposite legs of a multi-wire or "Edison" branch circuit), and certainly a 220V outlet will survive having a paltry 110V across it, but they are configured differently to keep dunderheads from plugging the wrong thing into the wrong outlet and having it fry due to the wrong voltage -- this was obviously a much bigger deal in the days before universal input power supplies, of course, but there is still plenty of stuff around that'd emit magic smoke if fed grossly wrong mains voltages.


Yes, the outlet connector is just plastic and metal. And it is quite likely that most any outlet made for 110V could handle 220V. And yes, you could connect 220V to an outlet designed for 110V (and vice-versa).

HOWEVER, the problem comes from the people who are USING the outlet. If an outlet has two flat slots for a 110V standard but it is wired to 220V, then when a user comes along and plugs in a 110V gadget, it will blow up (or burn up) from double over-voltage.

So mechanically, electrically, it is probably no hazard to connect a 110V outlet to 220V. But for practical purposes in the Real World, it is a REALLY REALLY TERRIBLE IDEA. And it is likely illegal as well.

Conversely, it is also not a good idea to connect a 220V outlet to 110V. Because many devices don't tolerate 50% UNDER voltage very well, either.

It is not clear WHY you are even asking this question, but I would recommend that you not pursue this line of thinking as it can only lead to disaster.


It's definitely a bad idea to wire a 110V outlet with 220V. In particular, 220V is usually accomplished in the US using two hot wires, a neutral, and a ground. But 110V outlets only have a connection for one hot; you really don't want to be putting that extra hot on the neutral or ground connections of a 110V outlet because very bad things will happen. But even if you somehow have a single wire with 220V to ground, if you were to wire that up, the device could melt, short circuit, burn, and just generally be a major safety hazard.

(This depends a bit on what country you're in. I'm guessing North America, since that's the main market with this combination of voltages.)

The correct outlets look very different depending on the voltage. In particular, the most common 220V outlets (NEMA 6-15) have horizontal pins where normal 15A/110V outlets (NEMA 5-15) have vertical pins.

Maybe you're mistaking a 20A outlet for a 220V outlet? It would be safe to put a 20A outlet on a 15A circuit, but you'd get circuit breaker trips if your device tries to use 20A. But, again, it's not safe to put a 15A outlet on a 20A circuit because the outlet (and presumably anything you plug in) isn't designed to handle the current.

In any case, you may get more useful discussion on the diy stackexchange.

  • 1
    \$\begingroup\$ Holy crap, that's a lot of different sockets... \$\endgroup\$ – marcelm Nov 14 '16 at 16:41

Obviously the difference is that the two are designed for different voltages. As voltage increases better insulation is needed.

In an outlet you have two kinds of insulation. One is a number of air gaps between various parts. Another is a number of parts made of non-conductive materials - plastic or ceramics. Both must be designed for higher voltages.

Distance between the outer surface of the outlet and the closest contact parts and stripped wires and screws or other parts holding those wires must be larger. Distance between any parts which are not electrically connected must also be larger. This also implies that the smallest possible outlet must also be larger. Outlet parts made of non-conductive materials must be made thicker to account for higher voltage.

It's unlikely that you actually face a situation where these differences cause problems in any reasonable scenario but possibility still exists. If anything goes wrong because of those differences it'll be your fault just because you used a part with the wrong voltage rating.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy