Electrical Outlet Ground Up or Down

Which way should a receptacle be mounted?

Example Reader comments on which way the electrical outlet should be installed: Ground connector up or down?

Ground "UP" causes cord stress or other trouble for some appliances

The reason I don’t like the up facing ground on an outlet is, items such as blow dryers have resettable breakers

and mounting the ground up eventually causes a short in the wiring because it stresses the cord.

The picture I included is the ground facing down and won’t ruin the wire.

On 2021-05-14 by Mr. Brian

Reply by (mod) - less damage likely to some power cords with the ground connection "down"

@Mr. Brian,

Thank you that's an interesting and very helpful remark. I agree with you completely.

I add that it's apparent from looking at the plug assembly itself that the manufacturer expects it to be positioned with the cord hanging down for the very reasons that you describe.

Or, put another way, the connector is designed for the way the manufacturer expects most plug-in connections to be made.

I've taken the liberty of flipping and straightening your photo lest we confuse other readers about "which way is the best way "up" for this receptacle"

Thanks again.

One comment regarding 'inverted' outlet mounting (ground up, vs down).

While not specified in the code, I have noted that several electricians PREFER to mount a switched outlet so that the ground prong is up while mounting the non-switched outlets with the ground down. That way the homeowner can quickly determine a switched from anon-switched outlet. - Anon 9/5/12

Thanks for the information - someone has said they like the ground prong up for a simple chance that if the ground prong is at the bottom and the extension cord gets somewhat loose and hangs that the two main prongs ( neutral /hot ) are exposed and it by chance some metal item may fall it could short it out or cause a spark and ignite (example: drapes ) as for the ground prong up all it will do is deflect it out of the way. - (Aug 14, 2014) F. Rego said:

Our electricians at work told me that they prefer to install the outlets with the ground conductor up because it reduces the chances of a metal object (i.e. paperclip) falling off of a desk and landing between the neutral and phase conductor.

With the ground conductor up, there is a better chance of such an object getting deflected or falling between the neutral and ground, which would be safer than falling between the neutral and phase conductor.

Although there is still a chance that an object might fall between ground and phase, it would be less likely than if the ground conductor was down. Because a typical 3-conductor plug is triangle in shape, an object is more likely to be deflected falling on the ground side than the phase / neutral side. - John said: 2 Aug 2015

Many more reader comments about grund opening up or down at recetpacles, including from homeowners, electricians, inspectors, etc. as well as some hints from manufacturers, are given on this page.

Modeator Reply: the position of installation of an electrical outlet won't affect its operation; insertion hazards at electrical receptacle slots

Anon, the position of installation of an electrical outlet won't affect its operation and should not normally affect its approval by the electrical inspector.

In some areas I see the outlet installed with the ground connector always "up" as in our photo, though to me that's less attractive than the position shown in our electrical outlet photo at far left.

There is an argument that ground-up is a safer installation for electrical receptacles that use a metal cover plate - as we discuss

at RECEPTACLE BOX COVER PLATES

I've also seen arguments expressing the OPINION that the position of the grounding pin connector might help resist the tendency of a plug to fall out of its connection. That's nonsense.

Watch out: If a device plug is falling out of a receptacle, one of the two objects is worn or damaged and should be replaced to assure a safe, mechanically secure connection.

Anon,

About upside down electrical outlets - thanks for the interesting comment.

Unfortunately because there's no standard mount position associated with switched electrical receptacles, the next owner in a home will probably be confused unless the secret code is passed-on to everyone.

Falling Paper Clip Contacting the Plug Terminals vs Insertion Hazards.

...

John:

Well as the Poughkeepsie police desk sergeant told our renter Anna M. when she complained that the Amtrack trains three miles away were too loud and that the cops ought to do something about it, ... "well that's one I've never heard before".

The claim that ground-connector up might reduce the chances of a live short across the hot and neutral spaces of a wall plug is technically plausible, though the probability of a paper clip or hairpin happening to fall onto a wall plug exactly into the gap that might appear at a wall plug that happens to not be plugged in far enough to prevent such contact seems to me to be rather small compared with other hazards.

It's the sort of explanation I used to make up before my friend Paul told me I was thinking too much and speculating too wildly.

What is a more-likely hazard at electrical receptacles is the insertion by children (or an adult fool) of a paperclip or other foreign object into the electrically live slots.

That concern has been addressed by research and by patents (Short 1989).

None of the patent citations considered the bad luck of a falling paperclip shorting an electrical receptacle or its wall plug. They all focus on inserted objects.

Thanks for the report, we'll keep it in the act.

Receptacle Installation Ground-Up with Metal Cover Plates

Reader Comment: install receptacles ground-up if metal receptacle cover plates are used

In cases where the outlet cover plate is metallic and held by the typical single screw, mounting the ground pin up prevents the cover plate from dropping across the phase and neutral conductors.

Of course, the cover plate screw would have to somehow be lost, but that never happens, right? - 2018/08/14 Tom West

Reply: Yes, a metal electrical receptacle cover can fall and short circuit across wall plug connectors

That's an interesting observation, Tom.

I agree that it's possible for a receptacle cover to slide down and contact the prongs of a wall plug but in

my OPINION that even is unlikely enough that it has not appeared in studies or standards that I have been able to find after several days of searching (August 2018 and again in 2022 and in 2024 - Ed.).

In our photo above I have completely-removed the receptacle mounting plate screw and I have pulled out the wall plug to afford room for the cover plate to slip down into contact with the plug connecting spades.

Watch out: however during the removal or unplugging of a wall plug it is more-likely that the cover plate, if not secured, could drop, shorting the hot and neutral plug connectors.

In contrast, if the plug remains fully inserted, a loose receptacle cover cannot easily contact the plug connectors.

Below, using a plastic face plate for safety, I show the edge of the receptacle cover plate touching the plug connectors.

You will note that the mounting screw was removed and the wall plug was partly withdrawn from the electrical receptacle.

Watch out: don't try this experiment yourself as you could be shocked, burned, or killed.

Because I made these photos in our lab where fires and shock injuries are discouraged, I used a non-conductive Bakelite plastic receptacle cover to demonstrate how a receptacle cover could contact wall plug connectors.

Details of different types of receptacle (and switch) face plates including a list of the factors that determine the probability that a metal face plate will slide down to create a short circuit on the wall plug connectors are

at ELECTRICAL RECEPTACLE BOX COVER PLATES

Electrical Receptacle "Outlet" Ground DOWN Support

Wall plugs come with ground connector oriented UP as well as DOWN

Plugs that lie flush come in both orientations.

On 2023-04-16 by Alan Rutherford -

Reply by InspectApedia Editor (mod) - ground DOWN avoids accidental finger contact with hot wall plug spade

@Alan Rutherford,

Ground up or down: NEC & Safest Position

Thanks for the photo, you're quite right - line cord wall plugs come in various orientations including with the ground connector "up" with respect to the line cord - as in your photo, or with it "down" and we've also got a few devices whose line cord wall plug can actually rotate to any desired angle (a more-expensive option).

Really? The line cord shown in your photo - in your hand - might want to actually be plugged-in upside down from how you're holding it if the line cord is going to extend upwards, for example to a large appliance like a microwave or a window air conditioner located above the wall receptacle.

So before we guess what the manufacturer of this line cord had in mind we need to see what's at the other end of that power cord and to know where it is going to be positioned with respect to the wall electrical receptacle or "outlet".

All of that means that the argument about ground-prong receptacle opening up or down a bit more debatable.

The U.S. National Electrical Code and the Canadian Electrical Code do not specify which direction is required: receptacles ("outlets") can be installed with the ground prong connector opening up or down - though there are plenty of opinions, some quite thoughtful, about which way is safest.

Still, I agree with expert Mike Holt's 1999 opinion: we prefer the ground in the lower or bottom or down position.

Mike pointed out that with the receptacle installed as in your photo, the installation is less safe as the ground prong can pull out while leaving the hot and neutral connectors still live or energized - a shock or even electrocution hazard, one that's increased as the line cord is being removed.

I think that this worry is why, as we see in your photo, the ground prong on the line cord plug itself is longer than the hot and neutral spaces of the plug.

The intention is that the ground should always be the last connector to break contact when the line cord wall plug is removed, and the first connector to make contact when the line cord wall plug is being inserted into an electrical receptacle.

Another argument for "ground prong down" in wall receptacles is that exactly as we can see in your own photo, the person's fingers are more-likely to be at the under-side of the line cord wall plug as it's being removed - a position in which a person's finger could cross the hot and neutral spaces (as in your photo) giving a bad shock.

On the other hand with the ground prong DOWN, the persons finger can only touch the ground connector, not a hot or live connector.

Examples of Manufacturer Installation Instructions for Receptacles: UP or DOWN

Reader comment: No website gives a definitive answer to ground up or ground down receptacle position

OK I've found no site that lays down any definitive reason answer - other than the impact of the rarely-used metal plate. But here's mine - while cords can be twisted, shorter ones like powerstrips seem to have the ground plug at the bottom.

So, while those in the industry may have varying technical reasons to vary, basic items seem to favor the one. And even if that's just ease-of-use and to not confuse average Joe, it means it'll never change. On 2021-12-01 by Carl -

Reply by Inspectapedia Com Moderator (mod) - Informal Survey of Receptacle Ground Connection "UP" or "DOWN" in wall receptacle instruction pamphlets - manufacturers go either way

@Carl,

Thank you for your comment.

Having researched this topic several times as well as fielded many comments as well as having installed and repaired electrical circuits for a long time, I have not found a - as you put it - definitive reason answer - so

in my OPINION there are just opinions and we have found no single compelling and authoritative "right" answer to the ground opening up or ground opening down argument.

There are advantages and disadvantages to either the up or down position of the ground prong connector.

First, we provide an an excerpt from Eaton's AF/GFCI INSTALLATION INSTRUCTIONS - Eaton [PDF] showing the receptacle with ground opening "up" - illustrated above.

Continuing our informal survey, Hubbell, another manufacturer, shows the receptacles installed with the ground connection "up" - illustrated just below, and excepted from

GFCI RECEPTACLE INSTALLATION INSTRUCTIONS - HUBBELL [PDF]

Above: notice that Hubbel has labeled the TEST and RESET buttons in both positions so that they can be read regardless of whether the ground connector opening is "up" or "down".

Also Lutron shows the ground connector "up" in these

GFCI INSTALL & TEST INSTRUCTIONS - Lutron [PDF]

But wait: here's another "Ground Prong Connector DOWN" example:

Leviton's non-GFCI receptacle installation instructions show the receptacle with the ground connector in the "down" position - illustrated below and in

ELECTRICAL RECEPTACLE INSTALLATION INSTRUCTIONS - Leviton [PDF] for the company's Acenti model receptacle

Below: Leviton's illustration shows the ground opening down on that receptacle.




Shown below is an equivalent illustration from another major electrical receptacle manufacturer, showing the ground receptacle opening in the "down" position - from

GFCI RECEPTACLE INSTALLATION INSTRUCTIONS [PDF] from Leviton

Really? The above are illustrations of electrical receptacles showing the ground up in some or down in others, excepted from the duplex or GFCI/AFCI receptacle installation instructions from several manufacturers.

None of these instructions tell the installer that the ground connection must be "up" nor do they insist it be "down". Wisely they've stayed out of the argument.

Summary of Points on Ground UP or DOWN at Electrical Receptacles on Walls

• Ground UP:
  
  A falling metal receptacle cover plate slipping down can contact hot and neutral if ground is DOWN - true, though nearly all new electrical work uses plastic cover plates. This is a possible, if probably uncommon hazard.
• Ground UP:
  
  a "more-stable" wall plug connection is provided.
  
  Really? We're still looking for research and testing that supports this claim. It's important, especially where safety is a concern, that we distinguish between opinion and authoritative research and also between safety and aesthetics.
• Ground UP
  
  for better help holding the wall plug in position? No supporting research has been found for this argument.
• Ground DOWN
  
  for better help in holding the wall plug in position? No supporting research has been found for this argument.
• Ground DOWN: for NEMA 14-50 ESVE
  
  Electrical Vehicle charging station connections gives an easier connection for some electric vehicle charging connectors. Standard is ground up but we've read on EV forums that many owners flip the receptacle over to ground down, e.g. for Porsche EVs.

• Ground DOWN: reduces stress on line cords
  
  that include built-in GFCI devices - as shown just above.
  
  At wall plugs indeed experts have observed that the greatest stress and occasional breaking of some of the copper stands in the cord occurs where the line cord enters the wall plug.
  
  Aronstein (personal communication to DF) points out that if you simply plug in an electric heater and then feel along its line cord with your hand, you'll often find that the hottest point is right where the line cord enters the wall plug.
  
  We think that's because of wear and breaking of some of the multi-strand copper strands at that location - mostly-caused by people wiggling the wall plug as they remove it, but possibly also caused by bending-over of the line cord on devices like the one shown in our photograph above.
• Ground DOWN: to avoid accidental finger contact with live plug spades during withdrawal
  
  with hot and neutral connectors is reduced, probably a more-common hazard than slipping-off metal receptacle cover plates. .
  
  In our OPINION this is a reasonable argument supporting GROUND DOWN installation of electrical receptacles. See Alan's photo just below and note the position of his fingers, and see our annotated copy of the same photo shown again just below.
  

Research: electrical receptacle installation position on walls, fires, hazards

• Allison, John. "Shock-resistant electrical outlet." U.S. Patent 6,455,789, issued September 24, 2002.
• Benfer, Matthew E. & Daniel T. Gottuk, DEVELOPMENT AND ANALYSIS OF ELECTRICAL RECEPTACLE FIRES [PDF] (2013), Hughes Associates, Inc., 3610 Commerce Drive, Suite 817 Baltimore, MD 21227 USA Tel: 410-737-8677 Webstite: www.haifire.com
  
  This report has not been published by the U.S. Department of Justice. To provide better customer service, NCJRS has made this Federally funded grant report available electronically. NCJRS is the National Criminal Justice Reference Service.
  Retrieved 2018/08/15, original source: https://www.ncjrs.gov/pdffiles1/nij/grants/243828.pdf
  Abstract:
  
  Laboratory testing evaluated the impact of a wide range of variables on the formation of overheating connections in residential duplex receptacles. Two types of receptacle configurations have been evaluated:
  
  1) those focused on terminal connections and
  
  2) those focused on plug connections.
  
  Testing included 528 receptacle trials, 408 trials with various terminal connections and 120 trials with various plug connections. Thirteen pre-fabricated wall assemblies of 36 receptacles were placed in 8 compartment fire tests and 5 furnace fire tests.
  
  The variables evaluated in the fire exposure testing included: the receptacle material, materials of the receptacle faceplate and box, terminal torque, and energized state of the receptacle.
  
  A portion of the receptacles in the fire exposure testing had overheated connections that were created in the laboratory testing. These receptacles were used to assess whether evidence of overheating would persist after a fire exposure. All receptacles were documented for damage to the receptacle, faceplate, and outlet box including any arcing, overheating, and/or melting.
  
  The results of laboratory testing indicate that only the loosest connections tend to form significant overheated connections irrespective of other variables, [emphasis added - Ed.] such as receptacle materials and installation.
  
  Forensic signatures of overheating have been identified and have been found to persist even after external fire exposure. In addition, locations of arcing within receptacles as a result of fire exposures were identified and characterized.
  
  The location of arcing is primarily dependent on the duration and intensity of the fire exposure, as well as the construction and materials of the receptacle, outlet box, and faceplate. The presence of characteristic indicators of arcing and melting were analyzed.
  
  

  Role of Receptacle Faceplates in Electrical Fires

  Benfer (2013) offers this description of the role of electric receptacle box cover faceplate materials:

  In the fire exposure tests, both plastic and metal were used for outlet boxes and faceplates. The use of different materials aimed to address the impact of the materials on electrical damage and thermal damage to the receptacles.

  For example, arcing can occur when energized conductors come into contact with properly grounded metal components. This cannot occur with the plastic outlet boxes and faceplates.

  Also, the plastic outlet boxes and faceplates will melt and deform when heated in a fire, while the metal components (i.e., steel) will not. This may cause different thermal damage to those items and potentially affect the thermal damage to the receptacle.  (Benfer 2013 p. 24).

  

  Nylon receptacle box faceplates: ..., for faceplates used in the laboratory testing where an overheating connection was present, there was generally a darkened and charred area where the overheating receptacle would have been in contact with the faceplate....
  
  ... It is likely that hotter local temperatures present for the overheating connections caused the dark discoloration, but because they were localized, they did not cause the faceplate to fall off. Op. Cit. p. 132 

  With increasing thermal damage, steel faceplates, like nylon, can partially-melt.

  

  Steel receptacle box faceplates: The maximum temperatures for the partially melted faceplates were much lower than the melting temperature of steel. - Op. Cit. p. 137

• Gizienski, John J., Stephen P. Short, and Robert J. Mellen. "Safety electrical tap." U.S. Patent 4,867,693, issued September 19, 1989.
• Hall, John Raymond. Home electrical fires. [Book] Quincy, MA: National Fire Protection Association, 2013.
• Hall, J.R. (2010), “Home Electrical Fires,” National Fire Protection Association, Quincy, MA.
• Richardson, Michael T. "Apparatus for recessing an electrical device in a wall." U.S. Patent 6,750,398, issued June 15, 2004.
• Short, Stephen P. "Safety electrical receptacle." U.S. Patent 4,867,694, issued September 19, 1989.
  Abstract:
  
  An electrical receptacle is provided with a shutter mechanism to block spurious insertion of a foreign object through one of the receptacle slots short of the receptacle power circuit contacts.
  
  This mechanism includes either one or two slides supported for movement between closed-latched and open positions.
  
  Access to the contacts requires the slides first be unlatched by a blade penetrating one receptacle slot and then cammed to open positions by another blade penetrating the other receptacle slot, as occurs incident to the insertion of a standard electrical plug into the receptacle.