American power outlets.

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American power outlets.

#1  Postby The_Metatron » Jul 25, 2017 7:46 pm

I think American power outlets are inferior to the European CEE 7/7 plugs and sockets. But, I work with what I have.

Here's a GFCI (ground fault circuit interruptor) outlet, installed in my kitchen.

IMG_1868.jpg
GFCI protected NEMA 5 outlet
IMG_1868.jpg (1003.91 KiB) Viewed 425 times


It is known as a National Electrical Manufacturer's Association (NEMA) type 5 outlet. This is the most common orientation for power outlets in the US.

First, to identify the three connections of one of these plugs. The short slot is the hot wire. Touch this one while touching a path to earth (ground), and you will get a shock from 120VAC. The longer slot is the neutral wire. The proper return path for power. The third connection is the safety ground. It isn't intended to be a return path for power. It's the equipment grounding pin to protect people from faulty user equipment in which the chassis has become hot. Its purpose is to ground that stray voltage, so you don't get electrocuted from simply touching a defective equipment item.

The question here is, which way should those plugs be oriented? Ground pin down, as you see in that GFCI installation, or ground pin up?

I looked around the internets for the proper way to install them according to the NEC, and the results are inconclusive. The NEC does not specify orientation. It does specify the wiring (hot, neutral, safety ground), as I have described it above. NECA, the National Electrical Contractor's Association, says they should be installed ground pin up. Both of those standards are behind paywalls, and I can't get to a real copy of one to be sure of these codes. But, this is what I'm finding on the internets.

As far as I can tell, the NECA guidelines specify the ground pin on top, in a vertical installation.

IMG_1869.jpg
NEMA 5 outlet
IMG_1869.jpg (646.4 KiB) Viewed 425 times


In a vertical installation (as shown), the ground pin is on top of each outlet. If the ground pin is up, that will prevent a conductive foreign object from falling onto the hot blade of the partially inserted plug. Likewise with the ground pin to the left, the neutral blade will be the one on top, again preventing a conductive foreign object from falling onto and contacting the hot blade of a partially inserted plug. Since most foreign objects aren't going to be falling up, this reason for these specific outlet orientations makes some sense.

There are other things that detract from the NECA guidelines, but I can only think of two specifics. First, there are low profile NEMA 5 power cords, in which the power cord leaves the plug body at a 90 degree angle. I've only seen these as manufactured cables, usually on washing machines and refrigerators, where they are plugged into an outlet and clearance between the appliance and the wall is a concern. Those power cords are always oriented to hang downward only if plugged into an outlet installed with the ground pins down. Likewise for many wall mounted small power supplies. If they are keyed at all to the long/short slot arrangement, they are made with the long slot on the left, with the output power cable egressing the bottom of the power supply.

In those two situations, I can see a possible problem with outlets installed ground pin up, as per NECA.

I read a few opinions in which people mentioned the operating instructions molded into the face of the outlet. Particularly, on most GFCI outlets. The test and reset button are clearly labeled. However, on close inspection, you can see that the lettering is molded into the test and reset buttons so they can be read properly in either orientation. But, I'm only looking at one GFCI outlet here. Along these lines, the current and voltage rating embossed onto the face of the plain NEMA 5 plug above is oriented to be read with the ground pin up. I don't think this is a very good indicator of which way they should be installed.

The instructions for the plain NEMA 5 outlets I bought have drawings which show the ground pin on the bottom orientation, but those instructions are only to show how to configure the outlet for switched operation.

IMG_1870.jpg
NEMA 5 outlet instructions
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My house was built in 1994, and the cheap bastards used the cheapest god damned outlets available. Over the entire house, it would have added less than 50 bucks to the cost of building it to use the best quality outlets available. Those cheap outlets have worn to a point where they don't retain power cords very well. So, I'm replacing all of them. I'm orienting them with the ground pins up.

What would you do?
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Re: American power outlets.

#2  Postby laklak » Jul 25, 2017 7:56 pm

Ground pin down seems to be the usual, but I can see why ground pin up might be a better choice. Down passes inspection here, as that's how the electricians wired the house when we refurbed it.

I've got the low profile plugs on all power strips (TV and such), and they definitely are built for a ground down installation. For that reason I'd go with down.
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Re: American power outlets.

#3  Postby Macdoc » Jul 25, 2017 8:03 pm

Ground down is more secure. You might want to add a few with built in USB sockets.
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Re: American power outlets.

#4  Postby laklak » Jul 25, 2017 8:09 pm

:this:

Put them in every room, they're brilliant. No more adaptors for cell phones, kindles, tablets....
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Re: American power outlets.

#5  Postby The_Metatron » Jul 25, 2017 9:24 pm

Macdoc wrote:Ground down is more secure. You might want to add a few with built in USB sockets.

I read that, too. But, no one was able to support it with tests results. I couldn't find any, either.


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Re: American power outlets.

#6  Postby The_Metatron » Jul 25, 2017 9:32 pm

If I had a spring scale, I could set up a simple test to see which orientation holds a given plug more securely, at various pull angles.

But, I don't have one.


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Re: American power outlets.

#7  Postby Macdoc » Jul 25, 2017 9:36 pm

I read that, too. But, no one was able to support it with tests results. I couldn't find any, either.


All you need to do it go into a motel room with worn sockets....those with ground up fall right out, those with ground down stay in place...the weight of the heavier side ( the prongs ) is supported by the ground plug
Flipped over....it just pulls out/falls out.

It's not obvious on new sockets, very obvious on worn sockets.

Just about every image of one is ground down

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Re: American power outlets.

#8  Postby tuco » Jul 25, 2017 10:05 pm

Its up over here, recommended by standard.

If the ground pin is up, that will prevent a conductive foreign object from falling onto the hot blade of the partially inserted plug.


We had one with down at home, and I did manage to insert conductive material (tin foil) behind the cover. Since I was inserting it from top, my heart got little boost :)
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Re: American power outlets.

#9  Postby theropod » Jul 25, 2017 10:11 pm

I have two whole circuits in my house, and no 220 v service. We do have CFI outlets, however, I mounted all those on circuit "A" with that third hole down and all those on circuit "B" with this prong up. Each circuit has its own steel distribution/breaker box. There are no inspections here unless required by the insurance folks. Being off the grid with a limited supply wattage running through our inverter (AIMS 3,000 watt pure sine wave) there is bloody small chance of an electical fire. Such an overload will trip the inverter, which also is GFI protected. My thinking is simplicity. I have my system set up so that either circuit A or B can be operated from a generator while the other runs off the batteries and inverter. I did this so that I could run the air conditioning without effecting the battery bank.

My intuition tells me it shouldn't really matter which way the ground prong is oriented.

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Re: American power outlets.

#10  Postby tuco » Jul 25, 2017 10:21 pm

I was told, that since up is recommend by standard, when inspectors come and see its down it rings their alarm bell as in: this was probably not done by a pro. Perhaps it does not matter from safety point of view but I guess there is no reason not to follow standard unless one does not know it.
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American power outlets.

#11  Postby felltoearth » Jul 26, 2017 2:38 am

I have UL approved flat plugs that only work in the ground down position.

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Re: American power outlets.

#12  Postby The_Metatron » Jul 26, 2017 2:51 am

felltoearth wrote:I have UL approved flat plugs that only work in the ground down position.

Image

That's one of the exceptions I mentioned earlier.


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Re: American power outlets.

#13  Postby Matt_B » Jul 26, 2017 5:35 am

It's ground down in Australia, but then again we are in the Southern Hemisphere.
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Re: American power outlets.

#14  Postby zulumoose » Jul 26, 2017 6:17 am

Ground up is the standard in the U.K. (rectangular pin) and in S.A. (round pin)
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Re: American power outlets.

#15  Postby Matt_B » Jul 26, 2017 7:16 am

zulumoose wrote:Ground up is the standard in the U.K. (rectangular pin) and in S.A. (round pin)
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Yeah, but with pins like that you hardly have to worry about it falling out of the socket, do you?
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Re: American power outlets.

#16  Postby zulumoose » Jul 26, 2017 7:33 am

Yeah, but with pins like that you hardly have to worry about it falling out of the socket, do you?


True. In both the U.K. and in S.A. the power plugs and adaptors from other places seem silly, flimsy and dangerous. I believe in the U.S. the power sockets don't even have on/off switches, everything is live leads all over the place (well, as live as they can be with such bad connections) and they build with wood (guffaw , guffaw). It's no coincidence the fire services are held in such high regard in the U.S.

When cell phones came out and everyone had to start using adaptors and 2pin plugs there was a lot of cursing. Horrible standards, I kept picturing an image of nurses in the ICU in America jiggling the plugs on the life support machines to get them working.
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Re: American power outlets.

#17  Postby Nicko » Jul 26, 2017 8:13 am

Image


Australian power socket. Vertical slot is the ground.

Interestingly, Chinese sockets are the same but inverted.

One idea occurs: is there some kind of anthropomorphic bias behind having the ground socket down?
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Re: American power outlets.

#18  Postby Scot Dutchy » Jul 26, 2017 9:41 am

The selection of European plugs and sockets. They do fit in all the EU countries. The earth connection varies.

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Re: American power outlets.

#19  Postby Briton » Jul 26, 2017 7:52 pm

zulumoose wrote:Ground up is the standard in the U.K. (rectangular pin) and in S.A. (round pin)
Image

Image


The British 15 amp used to be like that, round pin I mean. The move to 13 amp square pin added the fuse in the plug. Not often we Brits can claim to have the best system/design but I've not seen better.
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Re: American power outlets.

#20  Postby laklak » Jul 26, 2017 8:24 pm

Nah, ours is best, because 'Murika! Fuk YEAH!
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