One pin AC connector (Coaxial)

[Algr]

TL;DR

Coaxial plug/socket for line level power with an extra pin for data or DC.

I was reading about someone building a DC house, because this would make solar+battery more efficient. I was wondering what those plugs would look like, but found that there didn't seem to be any standard for DC 120v plugs and sockets. So I thought I'd try to make one, just for kicks:

This is based loosely on the 12v coaxial cable that most AC/DC adapters use. I figured that for 15A it would need to be bigger. It has four pins and so can carry both AC and DC, or 120v and 240v, or maybe AC and data. In the latter case, I'd figured the inner pin would be hot, while starting from the tip would be neutral, data, and ground. That way any foreign object being inserted in the plug would touch ground before anything else.
Those 12v coaxial connectors can rotate in their sockets. I figured that would be bad at 15 amps, so I made it square instead of round. It still inserts four ways. Any thoughts?

 

[DaveE]

It is standard practice these days for the ground connection to be made first and broken last when HV connectors are inserted or removed. This is in most safety standards.

Also, it looks kind of expensive, but IDK.

 

[Algr]

When you insert it, the ground would momentarily touch the neutral and the data pin before grounding the device, but would still connect before the hot wire. (So maybe the pin closest to the handle ought to cary data instead?). For clarity, I drew the internal metal visible in the hole, but it perhaps ought to be further back to assure it connects last.

This shouldn't cost much more than a headphone jack to manufacture. It doesn't need to be copper, the image just came out that way.

I'm presuming that the data pin isn't competing with ethernet, but is for USB 2 speeds. This is good for authentication and security, since physical access is necessary to connect to the network. The main thing I don't know how to calculate is if this will cary 15A safely.

 

[Guineafowl]

Would the jack for it be big enough to admit the finger of a toddler? I see ground would be outermost, but that could still result in a nasty injury. It also looks like something conductive inserted in there could short several circuits together.

As you insert the connector, different circuits of the load would contact the wrong pins, no?

It looks too easy to come into contact with live pins as the connector is pulled out (mind you, so does the one on the left). Being a sequential connector, it would be hard to solve that with sleeved pins.

No fuse(s)? Coming from the UK where they’re standard, I might be biased, but does it not make sense to protect the appliance flex from setting on fire?

 

[Algr]

It's about the size of a 1/4" headphone jack, so a toddler's finger would not fit. Also, the tip of the hot pin inside the socket (not shown) would be non-conductive. A fuse could be added by making the handle a bit larger. We have these in the US, but I've only ever seen them on christmas light strings. Since the plug is polarized, only one would be needed.

 

[Guineafowl]

Would it be big enough for 15A conductors?

Again, thinking through the sequential connection, when inserting the jack you would briefly connect N and ground. This could trip an RCD (GFCI) and rule out the design in the UK and EU.

 

[Averagesupernova]

In the USA low voltage wiring such as data, speaker wires, etc are not allowed to run in the same conduit and eventually receptacle box as the 120 volt power wiring.

 

[tech99]

A child could insert a metal object. Why not have a shutter to close the live terminal, as in the UK plug system?

 

[Averagesupernova]

Current code in the USA requires pretty much every receptacle to be tamper proof as @tech99 described.
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If you are serious about having input to develop a standard you need to be more informed. If this is just for fun, then I guess we'll just keep going as we are here.
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I know it has been tossed around for a while about using DC at higher voltages as described in this thread. It's a bad idea to me. Here's one reason: https://www.physicsforums.com/threa...cts-causes-and-solutions.880861/#post-5535189

 

[sophiecentaur]

It is standard practice these days for the ground connection to be made first and broken last when HV connectors are inserted or removed. This is in most safety standards.

I think there must be more to this jack than it appears. Those conductors are going to wipe across other (the wrong) conductors as the jack is inserted. IMO, the live and neutral in the receptacle must be lifted away from the rings on the jack or the could be an Earth-Neutral contact on the way in as the Load L and N go past the supply N and Earth. That would trip an RCD (above).

I guess I'm just re-stating the "shutter" word but the L and N should not be available till the jack is sitting snugly in position. Perhaps the hole down the centre could locate round a pin to make the mechanism work.

so a toddler's finger would not fit.

The house engineer where I worked showed me a British Standard finger

.

 

[Algr]

Again, thinking through the sequential connection, when inserting the jack you would briefly connect N and ground. This could trip an RCD (GFCI) and rule out the design in the UK and EU.

Uh oh. I was aware of the contact, but didn't know it was a problem. Back to work, I guess.

In the USA low voltage wiring such as data, speaker wires, etc are not allowed to run in the same conduit and eventually receptacle box as the 120 volt power wiring.

I guess that is why home ethernet never took off? There are networks that use the AC wires themselves to transmit data, so presumably if a networking standard is designed to be run this way, it would have protections. Does this apply to 12v power? Is there some danger of leakage or hot-to-hot contact?

A child could insert a metal object. Why not have a shutter to close the live terminal, as in the UK plug system?

I was thinking of the ground contact as being the shutter - a foreign object can't touch hot without also touching ground. But if the ground can't contact the neutral, then that will have to be different.

If you are serious about having input to develop a standard you need to be more informed. If this is just for fun, then I guess we'll just keep going as we are here.

I was seeing this thread as testing my knowledge, and seeing what I need to learn. I'm not expecting to propose this in congress tomorrow.

I know it has been tossed around for a while about using DC at higher voltages as described in this thread. It's a bad idea to me. Here's one reason: https://www.physicsforums.com/threa...cts-causes-and-solutions.880861/#post-5535189

Yikes! Maybe that DC house was all 12/24 volts? It could have been using appliances made for boats and RVs. But standard house wiring would transmit a lot less power. Vacuum cleaners and hair dryers will always need 120v, so it looks like AC isn't going away any time soon.

I think there must be more to this jack than it appears. Those conductors are going to wipe across other (the wrong) conductors as the jack is inserted. IMO, the live and neutral in the receptacle must be lifted away from the rings on the jack.

Yes, that is a good idea. I was worried about how close the neutral and hot pins in the socket would have to be to each other, and if there was risk of them making contact when no plug was inserted.

 

[Averagesupernova]

I was seeing this thread as testing my knowledge, and seeing what I need to learn.

Great! That's what this forum is for. Refreshing change from those who come here to argue that they can, or already have, broken the laws of physics. Or to claim they are above safety.
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[Averagesupernova]

I guess that is why home ethernet never took off? There are networks that use the AC wires themselves to transmit data, so presumably if a networking standard is designed to be run this way, it would have protections. Does this apply to 12v power? Is there some danger of leakage or hot-to-hot contact?

The NEC is very concerned about keeping 'everyone else's business' out of the equipment that the rules of the NEC govern. In other words, nothing can share a conduit or technically even be zip tied to a conduit. This begins at the meter and ends at the receptacle. NEC has no say in what you plug into an outlet. Local fire codes may. Many things today are sold on Amazon that are made to plug into a standard 120 volt outlet that should never be used. They are never UL listed but the NEC has no say. NEC also has no say in the wiring leading to your house prior to the meter. Their wiring (power company) is often several sizes smaller than what is between your meter and the breaker panel. Each job is evaluated by an engineer. The wiring after your meter and in your house is not.

 

[Averagesupernova]

While we are dreaming of a new type of connector that plugs into the wall for power I would make it triangular and keyed so it's impossible to plug in 120 degrees off. A contact on each side arranged so a specific order is achieved upon plugging in as to what makes contact first. Flipper door(s) could be utilized for safety against curious fingers.
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In all honesty though, I like what we have now.

 

[Algr]

Lots if interesting info, thank you!

The NEC is very concerned about keeping 'everyone else's business' out of the equipment that the rules of the NEC govern. In other words, nothing can share a conduit or technically even be zip tied to a conduit.

I see how this makes sense for Ethernet and RJ-11, since these standards were not built with this situation in mind. But a standard designed from the start to integrate data with power ought to be safe, as all the products would be built with shields to prevent the foreseeable problems. Perhaps data and 12v DC could share the same pin. As I said above, it needn't be as fast as Ethernet, it is for convenience and security.

I'm finding these products on the net:

I have the first one in my home. I presume this is okay because the USB only provides power and not data? I asked Amazon's AI if the second one was legal in the US, and it said "Check local regulations."

Their wiring (power company) is often several sizes smaller than what is between your meter and the breaker panel.

Sadly, no standard is going to stop people from cutting corners, unless the standard can be enforced.

I would make it triangular and keyed so it's impossible to plug in 120 degrees off.

That is the opposite of what I had in mind. Having to rotate the plug all over to find the right orientation can be a real pain in cramped situations. I designed it so orientation is irrelevant, like in headphone jacks and the EIAJ connector.

Or to claim they are above safety.

I am indeed above safety, but then I trip and fall on the safety and damage it. Ouch!

 

[Averagesupernova]

Having to rotate the plug all over to find the right orientation can be a real pain in cramped situations.

Agreed. Is there another way to maintain order of contact without excessive complexity? I can see a peg in the end of the plug that would activate all of the contacts at the last moment. Reliability, size and complexity becomes an issue. A triangular plug with redundant contacts all around would be closer but still require lining up. Three contacts on each side for hot, neutral and ground in the receptacle. But only one on each side of the plug. No matter how it's shoved in the correct contacts always line up. Still requires alignment +/- 60°.
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Could have a center peg for ground in the receptacle that goes up the center of the plug and sleeve and tip with the sleeve being larger on the plug. This could satisfy the order of contact and prevent contacts matting that are not supposed to. Reliability could be an issue. It's not likely to be adopted for AC to replace what we have. Higher voltage DC is unlikely to be utilized due to the issue of extinguishing the arc on switch contacts. Low voltage would be fine but it's not likely necessary to require a third wire for ground when the dc voltage gets low enough to be considered safe concerning switch arcing. Still, it never ceases to amaze me the number of various connector types that exist.