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I received a new Insignia Voice Speaker for work. It has a 2-prong cord, but all of my office outlets are 3-prong. I'm not finding a converter for this arrangement. Is it safe to plug the cord in as is?enter image description here

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    Aren't 99% of the outlets you've encountered in your life 3-prong? And aren't most of the cords you plug into them 2-prong? Why the concern?
    – isherwood
    Jan 17, 2018 at 14:13
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    Assuming this person has not been in the US for very long, I'd like to point out that if a plug physically fits into an outlet, its ok to do so. If you have to force it or bend it or do something else drastic, you're being dangerous.
    – JPhi1618
    Jan 17, 2018 at 14:35
  • Note that some two prong plugs are polarized: one prong is slightly bigger than the other. You have to orient them (Big prong in big slot, smaller prong in smaller slot). Dec 25, 2022 at 15:15

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As already pointed out, yes you can. But maybe understanding the why will help:

From this article, "https://electronics.howstuffworks.com/everyday-tech/question110.htm"

"The idea behind grounding is to protect the people who use metal-encased appliances from electric shock. The casing is connected directly to the ground prong."

So, chances are the device you are using would not electrocute you if a wire became loose inside and touched the casing. That is why there is not a need for the ground prong.

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Yes it is safe to plug a two prong electrical device into a standard 3 prong outlet.

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That 2-prong plug is a NEMA 1-15 type.

The universal-in-US NEMA 5-15 socket (Mr. Horrified) is specifically designed to accept both NEMA 5-15 and 1-15 plugs.

You will also run into NEMA 5-20 sockets (Mr. Winky). These are specifically designed to accept NEMA 1-15, 5-15 and 5-20 plugs.


The first number (1 or 5) is the NEMA series number. The second number (15 or 20) is the ampacity. North American utility receptacles are all 15A or 20A rated/breakered.

If you really, really, really want 240V in that same form factor, look at NEMA 6. It's rarely used in the US, but it's in the catalog and most hardware stores stock all the parts.

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Just a bit more detail:

The fact that a device doesn't have a three-prong plug means the manufacturer, and the safety certifying agency if any (usually Underwriter's Laboratories, or UL, for devices intended to nbe sold in the US) do not think it requires one.

In the case of the "wall wart" power supply you're showing us, this is because its output is low voltage, and because you'd literally have to break it open or soak the whole outlet in water to create a shock hazard.

For most modern 120V devices with US power cords, a two-wire power cord can be used if the device is "double-insulated". You can look up the definition of that, but basically it means breaking the outer case (by dropping it, for example) would not expose dangerous wiring.

There are a few other cases where you'll see a two-prong plug on new products. And unpolarized two-prong plugs used to be much more common, so you'll see them on older devices which don't have this extra layer of safety.

Modern products may also have polarized plugs, with one prong a bit wider than the other, so the manufacturer can guarantee that contacts most exposed to the user are connected to neutral rather than to 120V (assuming the outlet is wired correctly, of course). That too improves product safety, especially when combined with double insulation.

Welcome to the US!

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