Man dies charging phone in the bath ...

[Cubdriver]

I think it has to do everything with the plugs used in the USA. The first time I saw it in action, my reaction was this: The wiring code, the low voltage, the lack of grounding in too many equipment and plug...

Given the sheer number of those plugs and receptacles in use across the US, combined with the number of total morons here, if being electrocuted by the NEMA 5-15 plug and its kin was an issue we'd be aware of it by now.  ESPECIALLY if it were killing folks at a rate six times greater than in the UK.  There are a lot of electrocutions in the US, but there is also a great deal of industry and construction, too, and you'll find that is where most of them happen.  It's not people unplugging the vacuum cleaner and touching the prongs on the plug as they do so.

-Pat

[Red Squirrel]

It's also still hard to get your fingers to touch the prongs as if you can fit your fingers behind the plug chances are it's not in far enough to get contact.  McDonald's and fat fingers save lives! 

[CatalinaWOW]

For those thinking about a safer power plug.   Why not pull out all the stops.  Add about four more contacts for low voltage power and signaling.  Then your plug can report the VA requirements of your device, and the system can review the other loads on the circuit and decide if it is safe to power up.  Maybe even have a priority rating for each device, so that if an urgent device is plugged in some lower priority device elsewhere would be turned off to make room for it. And then as long as you are at it, and already have some intelligence designed into the plug, add a relay in the downstream side, and some voltage sensing and your device can decide if it will accept the supplied power or refuse to turn on.  Maybe a double relay system to eliminate the possibility of single point failures.  There are lots of opportunities to put more belts and more suspenders on this thing.

No one should be satisfied with a power plug system that is not as safe as it possibly could be.

[Housedad]

Any level of safety can be retrofitted into out homes, workplaces, and electrical goods.   All of the various types and methods to do so are available.  The problem is what are you willing to pay for it?   The more you protect, the more the cost and inconvenience.  Your choice.

there is definitely a way to be able to run a electric grill in the middle of a pool on 240V with the cord and connectors laying IN the water.  Hell you can make it safe with 50lbs of sodium chloride dissolved in the water.   Again,  what are you willing to pay for it?

[PointyOintment]

I like that three-ring design. The only thing that seems a little inelegant to me is that the two current-carrying contacts are substantially different sizes. A possible improvement could be to allow it to be plugged in in any orientation (well… maybe eight orientations), to make it easier to fit multiple wallwarts next to each other. This could be accomplished with a mechanical ring that accepts the locking nub and actuates the switch. Of course, there would be eight (or whatever number) nubs as well, for strength/redundancy.

For a while I have thought maybe we should analyze every plug design in common use worldwide as to advantages and disadvantages (electrical safety, foot safety, ease of manufacturing, cost, etc.) and design one with that knowledge to maximize the advantages and minimize the disadvantages.

[snip: TwoOfFive's design with the three rings and microswitch]

This adds a layer of safety, at the cost of redoing the world with a more complex design.  And you still could argue that a shutter would make it still safer because the microswitch could conceivably fail closed. 

The shutter could conceivably fail open.

(applies to 3 pin sockets only, 2pin ones in US are just to loose like the ones in the red light district  )

As a member of /r/badwomensanatomy I am obligated to point out that vaginas do not get loose as a result of having sex many times or with many partners. That's already off-topic, though, so I'll let you all look that up on your own time if you don't believe it.

More on-topic, my school has some carrel desks (desks with dividers) in the hallways and library, which are equipped with outlets to plug in your laptop/phone/whatever. When I plug in my laptop (ungrounded), it's always so loose that the plug literally falls out of the outlet if I so much as brush the cord. Many of these outlets also don't provide power, for reasons unknown to me, so I bought one of those three-neon-lamp outlet testers to carry around and test them with before getting out my laptop and its power adapter and setting them up. I found that the tester, though, sticks very well in the outlets; it has a ground pin. I guess the outlets are cheap and their live and neutral contacts are worn out from everyone plugging in their ungrounded laptop and phone power adapters. I kind of want to get or make a 'reverse cheater plug' to leave on my laptop's cord to provide it with a ground pin that does nothing electrically, but helps it stay in the outlets.

[CatalinaWOW]

There are things you can do to make a plug fit tighter (and make better contact) in a loose socket.  They are not really advisable since they often lead to sparks and smoke, and rarely to even worse things. 

Complain to the school, pointing out the risk to their insurance costs and legal liability if a student is injured.  It may motivate them to actually make repairs.

[Ampera]

Yea you could add more nubs to make it lock better. Maybe four, though, and have just one nub activate the microswitch.

I mean another reason why the NEMA standard is still used, it because it's INSANELY cheap.

https://goo.gl/LMGF7E

The cheapest one is 68 cents. I mean 68 cents, that is REALLY REALLY cheap. 100 outlets would be just 68 bucks, which is plenty for an entire house.

The advantage of mine is that you can make it cheap. The plug can just be looped sheet metal, and the outlet, which would require some plastic rings to insulate, could be something similar.

The reason I have designed it with neutral to be larger is then you have larger contacts for power going out than you do for power going in. It's really not needed, but hey, larger drain than tap means your sink doesn't overflow.

My design would also be very very small, which is an especially good thing compared to the British Standard which is MASSIVE. The rings would not need to be large, as the circular shape gives them a lot of surface area.

The outlets though, I think the best idea for contacts would be:

a pin in the middle for the live power

A plastic ring that would go around the live ring.

A metal ring that would go around previously mentioned plastic ring to make contact with the neutral ring

A plastic ring that would go around the neutral ring in the plug

And finally a metal ring that would go inside the ground ring to make contact with the ground ring.

Don't have time rn, but later I will make another 3D model.

[james_s]

The cause of loose plugs is usually cheap receptacles. The contacts inside the cheap builder grade ones are just single wipe, flimsy metal, they wear and get loose over time. Get a good quality spec grade receptacle and it will have a very noticeably better feel. If you really want to go all out, hospital grade are the best you can get but they are much more expensive and the there are diminishing returns on the added expense.

[PointyOintment]

The reason I have designed it with neutral to be larger is then you have larger contacts for power going out than you do for power going in. It's really not needed, but hey, larger drain than tap means your sink doesn't overflow.

Are you sure it works that way? Think of what a GFCI/RCD detects.

[Ampera]

Lol, yeah, It's not really a justification, but it's more of a side effect of the design. You definitely don't want a live connection large then your return connection. Take for example, the NEMA 1-15 polarized standard. It has a larger return pin than live pin.

[Cubdriver]

Uhh, you might want to think about the concept of a circuit for a bit.  All the current flowing out from one must (unless there is a fault condition) flow back in through the other.  And though they're labeled as hot and neutral, since what's supplied is alternating current, it flows 'out' from each terminal alternately 60 times every second.

The wider return neutral pin is a relatively recent (40-50 yrs) thing and done strictly for polarization, nothing to do with current carrying capacity.  Note that on a plug that also has a ground pin that both mains prongs are the same size - the ground pin provides polarization by only permitting the plug to be inserted in one orientation.

-Pat

<edit to change 'return' to the more correct 'neutral'>

[james_s]

Um, yeah, the water analogy is often used for electricity because it's a reasonable approximation using a medium that one can actually see and touch, but it's far from a perfect analogy. Electricity doesn't pool when there is an insufficient return path. It can't overflow. It makes no difference if the live terminal is 10 times the size of the neutral or the other way around, the current is always exactly the same on both. When dealing with AC the terms live and neutral are really rather meaningless anyway since the polarity changes every half cycle. The only thing it does tell you is that neutral (hopefully) shares the same potential as the ground you are standing on.

[Monkeh]

Lol, yeah, It's not really a justification, but it's more of a side effect of the design. You definitely don't want a live connection large then your return connection. Take for example, the NEMA 1-15 polarized standard. It has a larger return pin than live pin.

Why don't you? What will it do, make something catch fire?

It really doesn't matter what size the pin is so long as it's big enough. They don't have to match in any way.

[james_s]

Not to mention most grounded NEMA 15 plugs do not have a wider neutral prong, the prongs are the same size since the ground prong prevents plugging it in backwards.

[SingedFingers]

I see all this and then I remember it was only 30 years ago my nan was regularly tucking herself into bed, plugging her electric blanket into an extension lead hanging from the light fitting and lighting a final cigarette before drifting to sleep with it hanging out of her mouth on her nylon nightdress. Before bed she's sit there and watch her black and white valve TV which she'd replaced the fuse with some copper flex core curled up in a ball. If it was a cold night she'd leave the gas oven on in the kitchen with all the windows shut for a couple of hours before bed to heat the place up.

The woman was a life's education in a few minutes.

Fundamentally, whatever you build, the idiots will come.

[james_s]

Reminds me of when I'd walk to the nearby lawnmower repair shop to buy parts when I was a teenager, I'd frequently see one of the old guys who worked there pouring gas (petrol) out of something he was working on into a jug with a lighted cigarette dangling from his mouth. Always surprises me when I see someone like that actually make it to as old as he was.

[raspberrypi]

Tragic story, yes. But it could be worse. He could have been found in the bath with a mains wired breadboad on his chest and a Ben Heck video playing on the tele...

Does anyone else feel bad for that guy? He must have a terrible time getting laid. Looks like he got over his speech impediment pretty well. He almost looks like hes straight out of an episode of the simpsons. At least hes smart.

[PointyOintment]

There is, however, a valid reason for neutral to be smaller than live in NEMA 1-15: It's slightly easier to jam a metal tool into the neutral slot than the live slot, or, more importantly, it's slightly harder to jam a metal tool into the live slot than the neutral slot. Therefore, if one has to be larger for polarization or other mechanical reasons (such as the three-ring design), it should be the neutral.

[Marc M.]

I can't help but find it a bit ironic that in a thread discussing ignorance of electrical safety there's talk about the continued use of mains sockets that are so loose the plug falls out  

[Ian.M]

There's an easy fix for most of the issues with NEMA 1-15 - simply complete phasing it out.  You already cant install new NEMA 1-15 outlets, so ban the NEMA 1-15 two pin plug on new equipment or as a retail item, and introduce a requirement for all new NEMA 5-15 outlets, extension cords etc. to have shutters for the line and neutral, opened by the ground pin (an improvement to the existing tamper resistant requirements in many states) and a label prohibiting 2 pin plugs, and tighten up the requirements for retention force.

Of course that doesn't help with the unshrouded pins issue, but with only 0.06" blade thickness to work with, its difficult to shroud the pins without increasing the risk of them breaking off in the socket.

With the average life of modern electrical goods being as low as it is, and the gradual reduction is sockets that would accept them, that could remove half the NEMA 1-15 plugs from consumers within five years, rising to 9/10 within ten years

Some concessions may be needed for repair parts sold only to a licensed electrician, with a sizeable fine if they are resold other than as parts used during a repair, and rewards for reporting contraventions funded by the fines.

[Monkeh]

A similar process could see 240V outlets deployed for use with modern equipment with switching supplies - nearly all of which is designed for 240V operation and measurably more efficient there. 2-3% doesn't sound like much, but it's entire power plants..

[Ian.M]

A simple code requirement that all new 120V outlets must be within 1 yard of a 240V outlet and the number of 120V outlets in a room must not exceed the number of 240V outlets could do that, but IMHO that's a step too far.  Maybe just slap a tax on 120V plugs and outlets?

[tooki]

I can't help but find it a bit ironic that in a thread discussing ignorance of electrical safety there's talk about the continued use of mains sockets that are so loose the plug falls out  

We must have been reading different threads, because in this one, the advice continues to be "replace loose receptacles with new ones".

[tooki]

... tighten up the requirements for retention force.

A truly sensible suggestion, but absent data showing real hazard from loose sockets (like fires and electrocution), not just inconvenience, it's never gonna happen.

Of course that doesn't help with the unshrouded pins issue, but with only 0.06" blade thickness to work with, its difficult to shroud the pins without increasing the risk of them breaking off in the socket.

We don't have to speculate on this: Australia uses sheathed blades that are almost identical in dimension to NEMA blades. If there isn't already data on this, at minimum we have actual mass-produced product we could put through testing to find out if this is actually a problem or not. (My guess is that since they've been widespread in Australia for a decade IIRC, if they were problematic, we'd know about it already.)

[firewalker]

Not sure if true or trolling, but:





Alexander.