6 ms·

Short form: Neutral is grounded. The "mouth" part of the plug is the ground and is isolated from the neutral to prevent inadvertent carrying of potential. Asi

Short form: Neutral is grounded. The "mouth" part of the plug is the ground and is isolated from the neutral to prevent inadvertent carrying of potential. Aside: it is generally considered safer to have the outlets ("receptacles") installed with the ground at the top, but we don't tend to do this in NA because ground at the bottom makes it look like a little face and humans like faces. Edit: Adding link to EETimes: https://www.eetimes.com/document.asp?doc_id=1272972# https://www.eetimes.com/document.asp?doc_id=1272972#

count 7y ago
I recently remodeled a house (in the US), and installed every receptacle with the ground at the top, because of that. Every person who comes over that knows anything about electrical stuff instantly says 'your plugs are upside down'...and then I have to explain to them how/why it works :) The inspector had no issue with it though, thankfully! In health/saftey critical installs (like hospitals), the ground MUST be on top, according to our local code. It's optional for residential.
- throw0101a 7y ago
  > I recently remodeled a house (in the US), and installed every receptacle with the ground at the top, because of that. Have you run into any appliances or devices that are "optimized" for a ground-down configuration?
  - kevin_thibedeau 7y ago
    Low profile plugs intended to have the cord exit downward at 45-degrees don't work as well with upside down receptacles.
  - count 7y ago
    Nothing so far. Most all appliances these days are single-device circuits (in the new kitchen, literally every appliance required a dedicated circuit - fridge, gas range, microwave, ovens, dishwasher, garbage disposal, etc.). So, lots of single-plug receptacles (code says a dedicated circuit has to have a special single plug receptacle here). No issues so far with anything.
- clinta 7y ago
  Do your wall warts fall off the wall?
  - blacksmith_tb 7y ago
    AC adapters are rarely 3-prong? If they were, though, I'd expect the to stay in better, even upside down.
    - btgeekboy 7y ago
      They’re not 3-prong, but many are polarized.
      - yardie 7y ago
        I've rarely seen a DC transformer that is also polarized. It's literally a coil of wire passing from hot to neutral. Which way doesn't matter as it's rectified from AC pos/neg to DC +wire -wire.
  - linsomniac 7y ago
    Usually I find that wall warts falling off is due to the receptacle being "past it's prime" and replacing it takes care of it. I can't think of when I've seen a polarized wall wart, so you can sell place one in the lower outlet facing down, and the upper one has to face up usually because they hang down and interfere with the lower port. Aside: One regret I have in my kitchen remodel is not replacing all the boxes with dual gang.
- c22 7y ago
  I remember seeing a couple places with their outlets installed this way several years ago and seeking out the reasoning at that time. I never liked the way wall warts fall out of "upside down" sockets, though, so when I had to install a bunch of outlets recently I put them all on their sides with the neutral leg "up".
  - count 7y ago
    That's not a bad idea either, although I'm sure I'd get even more questions as to why all my outlets were on their sides! Also those 1-gang boxes are more expensive...
- magduf 7y ago
  Your explanation was likely wrong then, because there's no good reason to install your receptacles that way, unless your faceplates are metal. If they're plastic, then there's no reason for it.
  - shawnz 7y ago
    Huh? I thought the reason for putting ground facing up was to prevent metal things from falling in from above and shorting the live and neutral together. What does that have to do with the material of the faceplate?
    - jethro_tell 7y ago
      Because a metal face-plate is the most likely item to fall in there. Especially in industrial places like warehouses and hospitals where there's a lot of stuff rolling around and everything is high traffic.
      - pixl97 7y ago
        Really I've found flat materials falling off the back ofdesks to be a pretty common method of shorting said prongs. Even upside down it is still a problem with ungrounded devices like phone chargers.
    - count 7y ago
      The reason for putting it ground up is that the vast majority of plug insertions occurs from above, with the plug angled down into the socket. This assures that the ground connector goes in first, as it's at the top, so you get the safety ground before any of the connections are made. It's also a nice benefit that if something were to fall between the plug and the faceplate that it'd hit the ground and not short things (or short to the plate itself if it were metal).
      - shawnz 7y ago
        This doesn't seem right to me. Given how the contacts are positioned deep in the socket, they wouldn't be reached if the plug isn't being inserted straight. Plus the ground pin is already slightly longer to mitigate this issue. Do you have a source for this explanation?
- linsomniac 7y ago
  My brother in law lives in a fairly recently constructed house, and I commented that one of his receptacles was "upside down". He explained that the electrician did that for the switched outlets so you can tell by looking at them. He then asked if there was anything wrong with it? "Nope, it's actually code in most hospitals to do that, but residential doesn't. Just wondered." It's an interesting way of indicating switched.
HillaryBriss 7y ago
To extend this short form a little bit: at least for me, a key insight of this article was: Depending on the height of your circuitry above the earth's surface, depending on the area covered by your wires, and depending on whether there was a thunderstorm above you at the time, there might be a fairly huge DC charge on your electrical distribution system. So, the article offers an explanation of why it's really useful to ground one of the two AC wires in the first place: AC generated by the power company may not be the only source of electrical charge on the wires. I must admit, that was not something I thought about before.
Someone1234 7y ago
> Aside: it is generally considered safer to have the outlets ("receptacles") installed with the ground at the top, but we don't tend to do this in NA because ground at the bottom makes it look like a little face and humans like faces. I'm not sure there's any basis for this. See this article for example: https://www.archtoolbox.com/materials-systems/electrical/groundorientation.html https://www.archtoolbox.com/materials-systems/electrical/gro... The real reason why this was done historically was perhaps due to this: > Back in those days, there were very few plastic faceplates on AC receptacles and switches. They were almost all made of metal. All that holds a faceplate in position is one short screw for an AC receptacle. If the screw loosens and falls out, the faceplate will drop down and short out the two power prongs on anything that is plugged into that outlet. Such accidents used to be commonplace which is why power receptacles were put in upside down. With plastic faceplates it no longer applies. Which is why most newer medical facilities have them in regularly facing. It was done for a reason, but people forgot what that reason is, then myth turned into legend and people kept doing it cargo cult style without knowing why it started ("safer" requires an explanation). The whole "drop a metal tool" justification was likely a rationalization to a practice people didn't understand, but doesn't actually make sense. That all being said, it isn't less safe to put them "upside down." It just might interfere with some consumer electronics that assume a certain orientation (like those plugged in perfume bottles, smart home sensors, or similar).
- magduf 7y ago
  This is exactly correct, and electrical code still requires the "faces" to be upside-down if the electrical box has a metal faceplate, which is still common in many industrial settings and also house basements. If the faceplate is plastic, it doesn't matter. Also, in many houses you'll see the outlets oriented both ways in living and bedrooms, and there's a reason for this: what you'll see is all the outlets oriented one way (usually with the "face" right-side up), except for one outlet, which is upside-down. That outlet is the one that's controlled by a wall switch, so you're supposed to plug a floor lamp into it, which can then be switched on with the wall switch when you enter the room. Inverting that one outlet makes it much easier to see which outlet you're supposed to use.

count 7y ago

I recently remodeled a house (in the US), and installed every receptacle with the ground at the top, because of that. Every person who comes over that knows anything about electrical stuff instantly says 'your plugs are upside down'...and then I have to explain to them how/why it works :) The inspector had no issue with it though, thankfully! In health/saftey critical installs (like hospitals), the ground MUST be on top, according to our local code. It's optional for residential.

throw0101a 7y ago
> I recently remodeled a house (in the US), and installed every receptacle with the ground at the top, because of that. Have you run into any appliances or devices that are "optimized" for a ground-down configuration?
- kevin_thibedeau 7y ago
  Low profile plugs intended to have the cord exit downward at 45-degrees don't work as well with upside down receptacles.
- count 7y ago
  Nothing so far. Most all appliances these days are single-device circuits (in the new kitchen, literally every appliance required a dedicated circuit - fridge, gas range, microwave, ovens, dishwasher, garbage disposal, etc.). So, lots of single-plug receptacles (code says a dedicated circuit has to have a special single plug receptacle here). No issues so far with anything.
clinta 7y ago
Do your wall warts fall off the wall?
- blacksmith_tb 7y ago
  AC adapters are rarely 3-prong? If they were, though, I'd expect the to stay in better, even upside down.
  - btgeekboy 7y ago
    They’re not 3-prong, but many are polarized.
    - yardie 7y ago
      I've rarely seen a DC transformer that is also polarized. It's literally a coil of wire passing from hot to neutral. Which way doesn't matter as it's rectified from AC pos/neg to DC +wire -wire.
- linsomniac 7y ago
  Usually I find that wall warts falling off is due to the receptacle being "past it's prime" and replacing it takes care of it. I can't think of when I've seen a polarized wall wart, so you can sell place one in the lower outlet facing down, and the upper one has to face up usually because they hang down and interfere with the lower port. Aside: One regret I have in my kitchen remodel is not replacing all the boxes with dual gang.
c22 7y ago
I remember seeing a couple places with their outlets installed this way several years ago and seeking out the reasoning at that time. I never liked the way wall warts fall out of "upside down" sockets, though, so when I had to install a bunch of outlets recently I put them all on their sides with the neutral leg "up".
- count 7y ago
  That's not a bad idea either, although I'm sure I'd get even more questions as to why all my outlets were on their sides! Also those 1-gang boxes are more expensive...
magduf 7y ago
Your explanation was likely wrong then, because there's no good reason to install your receptacles that way, unless your faceplates are metal. If they're plastic, then there's no reason for it.
- shawnz 7y ago
  Huh? I thought the reason for putting ground facing up was to prevent metal things from falling in from above and shorting the live and neutral together. What does that have to do with the material of the faceplate?
  - jethro_tell 7y ago
    Because a metal face-plate is the most likely item to fall in there. Especially in industrial places like warehouses and hospitals where there's a lot of stuff rolling around and everything is high traffic.
    - pixl97 7y ago
      Really I've found flat materials falling off the back ofdesks to be a pretty common method of shorting said prongs. Even upside down it is still a problem with ungrounded devices like phone chargers.
  - count 7y ago
    The reason for putting it ground up is that the vast majority of plug insertions occurs from above, with the plug angled down into the socket. This assures that the ground connector goes in first, as it's at the top, so you get the safety ground before any of the connections are made. It's also a nice benefit that if something were to fall between the plug and the faceplate that it'd hit the ground and not short things (or short to the plate itself if it were metal).
    - shawnz 7y ago
      This doesn't seem right to me. Given how the contacts are positioned deep in the socket, they wouldn't be reached if the plug isn't being inserted straight. Plus the ground pin is already slightly longer to mitigate this issue. Do you have a source for this explanation?
linsomniac 7y ago
My brother in law lives in a fairly recently constructed house, and I commented that one of his receptacles was "upside down". He explained that the electrician did that for the switched outlets so you can tell by looking at them. He then asked if there was anything wrong with it? "Nope, it's actually code in most hospitals to do that, but residential doesn't. Just wondered." It's an interesting way of indicating switched.

HillaryBriss 7y ago

To extend this short form a little bit: at least for me, a key insight of this article was: Depending on the height of your circuitry above the earth's surface, depending on the area covered by your wires, and depending on whether there was a thunderstorm above you at the time, there might be a fairly huge DC charge on your electrical distribution system. So, the article offers an explanation of why it's really useful to ground one of the two AC wires in the first place: AC generated by the power company may not be the only source of electrical charge on the wires. I must admit, that was not something I thought about before.

Someone1234 7y ago

> Aside: it is generally considered safer to have the outlets ("receptacles") installed with the ground at the top, but we don't tend to do this in NA because ground at the bottom makes it look like a little face and humans like faces. I'm not sure there's any basis for this. See this article for example: https://www.archtoolbox.com/materials-systems/electrical/groundorientation.html https://www.archtoolbox.com/materials-systems/electrical/gro... The real reason why this was done historically was perhaps due to this: > Back in those days, there were very few plastic faceplates on AC receptacles and switches. They were almost all made of metal. All that holds a faceplate in position is one short screw for an AC receptacle. If the screw loosens and falls out, the faceplate will drop down and short out the two power prongs on anything that is plugged into that outlet. Such accidents used to be commonplace which is why power receptacles were put in upside down. With plastic faceplates it no longer applies. Which is why most newer medical facilities have them in regularly facing. It was done for a reason, but people forgot what that reason is, then myth turned into legend and people kept doing it cargo cult style without knowing why it started ("safer" requires an explanation). The whole "drop a metal tool" justification was likely a rationalization to a practice people didn't understand, but doesn't actually make sense. That all being said, it isn't less safe to put them "upside down." It just might interfere with some consumer electronics that assume a certain orientation (like those plugged in perfume bottles, smart home sensors, or similar).

magduf 7y ago
This is exactly correct, and electrical code still requires the "faces" to be upside-down if the electrical box has a metal faceplate, which is still common in many industrial settings and also house basements. If the faceplate is plastic, it doesn't matter. Also, in many houses you'll see the outlets oriented both ways in living and bedrooms, and there's a reason for this: what you'll see is all the outlets oriented one way (usually with the "face" right-side up), except for one outlet, which is upside-down. That outlet is the one that's controlled by a wall switch, so you're supposed to plug a floor lamp into it, which can then be switched on with the wall switch when you enter the room. Inverting that one outlet makes it much easier to see which outlet you're supposed to use.