22 ms·

So Where’s My Low Voltage DC Wall Socket?

81 points by kyancey 7y ago

theandrewbailey 7y ago
> ...and incorporate a fuse to protect the appliance cable from fire. Those British BS1363, fused-mains-plug habits die hard. Lots of car barrel connectors have fuses inside. I'm not seeing much reasoning behind not using the car barrel connectors, aside from 'it was designed for cars, not as a general purpose connector'.
- consp 7y ago
  They break easily. Spring loaded bits (actual springs). No properly defined standard and they vary a lot. Come out easily depending on quality. Easy to contact center pole to side poles on insertion. No ability to add earth.
  - Jamwinner 7y ago
    12v plugs are indeed a standard, and can be quite robust. Other than size and cost, there are no such downsides. On DC there is seldom an 'earth', gound is analougous to dc negative/neutral depending on local standard. ANSI/SAE J563 and UL2089 https://en.m.wikipedia.org/wiki/Cigarette_lighter_receptacle https://en.m.wikipedia.org/wiki/Cigarette_lighter_receptacle shows the UL standard.
    - consp 7y ago
      The case was made as a dc plug in general. Though 12V does definitely not require "earthing", you are correct about that. With earth in this case it is not the ground perse but some connection schemes (and standards) require either a third connector or open return path for DC which this connector cannot provide. Apparently they decided to make it a standard in 1994 after years of mismatching equipment all over the world, which is longer than I would have ever guessed. Interesting to see. Apparently UL "standard" does not translate well to actual standard. My experience is that most devices fail on the spring center contact, and do not fit for all cars. Anecdotal but still: even the expensive charger I have doesn't work in one car I've owned (opel) due to the misalignment of the outer contacts and it jumps out too much). It says it's UL2089 compatible though so I guess opel was at fault. There are so many "extension cords" out in the wild which hardly work or go lose after time due to bad design or because they are just a bit too wide. I own several of them and have thrown most away. The funny thing is the standard describes two sockets with differing size which is not helpful in any way and looks like a legacy of some manufacturers made into the standard. The article also mentions other bad characteristics about the connector and plug like bad contact causing high resistance which is simple due to the design but might also be present with other designs of course. I mean, it's nice it became a standard as it was in every car anyway since everybody smoked in them but there are way better solutions which do not have the problems I already mentioned and are way better solution for home appliances. If there is not yet a proper standard, why chose one which is not designed for this usage and most definitely was never designed for what it is used for today with all kinds of side effects (good or bad).
  - jessaustin 7y ago
    I agree that these connectors are typically low-quality. I can't imagine ever needing to earth them, however.
- mark-r 7y ago
  Car connectors are ugly, oversized, and mechanically questionable. They do work though - I once used one to hook a solar cell to a 12V fan.
nickhalfasleep 7y ago
No mention of Power-over-ethernet?
- mark-r 7y ago
  What is the maximum power provided by PoE? Wikipedia is surprisingly vague on the subject, probably because there are multiple standards. PoE was never intended to power more than just network equipment.
  - mumrah 7y ago
    I think it's something like 30W over a single ethernet cable. I'm running a few devices with PoE that are not network enabled, just conveniently located near an ethernet cable that's not near a power outlet.
  - steve19 7y ago
    I am not sure how Wikipedia can be more explicit, they even have a table showing the voltages and wattages of the different standards. [0] According to that table, the latest standard, 802.3bt Type 4, can provide 71 W to the device at the end of the cable (and inject 100W into the otherside). [0] https://en.wikipedia.org/wiki/Power_over_Ethernet https://en.wikipedia.org/wiki/Power_over_Ethernet
    - mark-r 7y ago
      Clicking on the link "Power capacity limits" brings you to nothing useful. Are you looking elsewhere?
      - steve19 7y ago
        Scroll down to the table "Comparison of PoE parameters".
  - vetinari 7y ago
    Depends on how you define "network equipment" :) Unifi is selling LED panels, that are powered over PoE and controlled over Ethernet.
jon-wood 7y ago
I don't get why they write off USB so quickly. It's small, it's reasonably convenient, and is almost ubiquitous already.
- ocdtrekkie 7y ago
  The article explains: USB A's power is too limited for a large percentage of household uses, and USB C is complicated and expensive, requiring digital circuitry to negotiate.
- zwieback 7y ago
  The current USB standards are great for small devices but for anything that requires more power it would be good to have something beefier, something less than the roughly 1500W a standard AC outlet provides but more than the current 15W or 20W of the typical USB port. 5V is just too low and requires a lot of compromise on the device side. I'd probably start with 12V or 24V to keep the current lower. I think there are newer USB ideas to provide something of that sort: https://www.digikey.com/en/articles/techzone/2017/mar/designing-in-usb-type-c-and-using-power-delivery-for-rapid-charging https://www.digikey.com/en/articles/techzone/2017/mar/design...
baybal2 7y ago
The telecom industry has 48 volt as a de-facto standard, bur never came to a mechanical standard. Thus you see daisy chains of mechanical adaptors in telecom closets.
- kjs3 7y ago
  Well...the daisy chains were the standard for mechanical connections. :-) What there never was was a connection standard safe enough to put in a house, made to be (ab)used by normal people. 48v DC as it lives in the telco world is flat out dangerous if you aren't careful.
rhinoceraptor 7y ago
It seems like USB A/C are going to be that. You can already buy outlets that have both mains and USB ports, there are even dual USB C outlets now, that can do 30 watts: https://www.amazon.com/dp/B07PTWG5DV https://www.amazon.com/dp/B07PTWG5DV
- Spooky23 7y ago
  The author makes the valid point that USB-A is too low power, and USB-C requires active cables. (Translation: expensive or dangerous)
  - kevin_thibedeau 7y ago
    USB-A can support power delivery. The standard predates USB-C.
    - joecool1029 7y ago
      In practice I haven't seen USB PD 1.0 in the wild. Most of the non-PD charge standards signal charge rates using varied voltages on the D+/D- lines. When current manufacturers claim USB-PD they mean PD 2.0 which requires the CC line (Only included in usb-c to usb-c) to signal and set the voltage. When PD 3.0 is included, they usually call it quickcharge 4.0 or PPS.
  - Johnny555 7y ago
    If you want one port that can charge multiple devices of varying needs safely, you need smarter cables. Sounds like a reasonable tradeoff. Otherwise every single cable would have to be built to handle the highest possible power delivery rate (100W for USB-C).
    - lostlogin 7y ago
      Looking at that plug and how chunky the holes are for ac power, when access is limited and you can’t see, shoving a usb c plug into the ac hole is going to happen often.
alexhutcheson 7y ago
Interesting idea, but running an extra set of cables is a non-starter. The cost/benefit analysis would never make sense for existing structures, and newly built structures wouldn't do it unless it was almost certain to become a universal standard. This is a classic chicken-and-egg problem. You would also still need something similar to a wall-wart to step down the voltage to whatever your device actually uses (e.g. from 12 V to 5 V to charge your phone), so its not clear how much benefit there would really be from such a system. Whatever specs we adopted would probably also end up not being appropriate for some future devices, so we'd probably go back to a substantial number of devices bundling their own PSUs anyway. Interesting idea, unlikely to ever be worth the cost. If wall-warts really bother you, then just invest in some wall outlets with integrated USB sockets - there are many good options on the market.
- gwbas1c 7y ago
  Also, the biggest non-starter is just how inefficient it is to move 12v any reasonable length. 12v domestic wiring only makes sense in very tiny small dwellings. (Think studio apartment or 3rd world country shack.) Otherwise the voltage sag and resistance makes it cheaper and more efficient to do normal 120/240 voltage with device-specific converters. (For example, if I had to run 0-gauge cable from my breaker box throughout my house to support 12v, the cost of copper alone would be prohibitive.) I honestly think standardizing on USB for devices that can use it is the best approach, given that we already have tiny AC->USB converters that don't block other plugs, and outlets with USB built-in are on the market. Furthermore, I wonder just how much we can shrink the typical wall-wart so it won't cover other plugs? (I also think we're better off trying to do a global domestic 200 or 400 volt DC standard.)
forgotmypwd123 7y ago
I always thought running low-voltage DC through a house from a single supply was doomed due to voltage drop over the distances required....
- mark-r 7y ago
  You could counteract that with heavier wires, but house wiring is already awkward and expensive.
- zzzcpan 7y ago
  Well, there is less drop with more copper, so it's more about costs. Cost of cables, DC-DC converters, power supplies and their efficiency determine optimal configuration. Probably going as high as cheap mass market DC-DC converters and PSUs allow is good rule of thumb for low voltage, so like 20-24 V. Beyond that better to go with high voltage.
  - logfromblammo 7y ago
    For some reason, I feel like 48V DC over super-chunky aluminum bus bars is the only way you could avoid making the DC whole-house wiring cost less than the entire rest of the house. As I understand it, the problems that make aluminum wire strictly inferior to copper wire--expansion coefficient, heat dissipation, non-conductive oxide, and strand breakage--are less significant in bus bars. The remaining concerns would then be bimetallic junction corrosion and work hardening. Maybe a bus duct with polybenzimidazole spacers and insulation? Still sounds expensive and inefficient, though.
- gmueckl 7y ago
  You have to choose wire gauges carefully. A lot of cables that connect power supplies to their devices have thin wires that don't loae much voltage over the meter or so of cable. But if you woukd extend that with an equal gauge wire to some meters if length, the conmected device will likely burn out around then as well.
- aivisol 7y ago
  That absolutely is. You could be better with 48 or even 24 volts, but then you are out of luck if you want to power a majority of devices which are 12v. So your only option is to go for USB-A wall socket which essentially is a wall-wart hidden in your wall. I do not see a good solution here.
ethagknight 7y ago
Is "Digital Electricity" a real thing? Its billed as an alternative to AC or DC. This may be as good a place as any to ask this question, but I am a hotel developer, and we've had a few people reaching out to us trying to sell "digital electricity" that sends high voltage over cat5 (up to 2000w per the Belden materials) by essentially sending high voltage for very brief blips with the ability to switch off before any damage occurs if a short is detected. they claim it is supposed to be significantly more efficient, doesn't require electricians to run cables, and its safer. I declined... but im still curious. basically every device in the room is connected via lan to a power server. https://www.belden.com/blog/smart-building/digital-electricity-5-things-you-need-to-know https://www.belden.com/blog/smart-building/digital-electrici...
- Danieru 7y ago
  Oh wow, I would not want 2000w going through Ethernet. Both for the obvious electrical issues, and for the dangerous mixing of safe sockets and hot sockets. No idea how this would be more efficient. Bursting voltage will lead to higher loses versus a continuous voltage. Are they claiming efficiency thanks to a centralized AC->DC converter?
  - gmueckl 7y ago
    Cat5 doesn't imply RJ45, so that confusion could be easily averted if people with brains developed that stuff. 2000w constant power transmission on a Cat5 sounds dubious, though. I don't know at what the voltage such a cable gives in and shorts wires. It would have to be pretty high to get the current to something the wire crossection can handle.
    - jacquesm 7y ago
      It's not the wattage that is going the be the problem, but either the high current or the high voltage (arcing).
- pjc50 7y ago
  That sounds like the sort of thing your local electrical code authority might get very upset about. It's not clear what the actual voltage is? But if it's over "SELV" ratings different rules are going to apply.
alexhutcheson 7y ago
Comments below the original post are great.
rb808 7y ago
I dont think DC wall socket is the problem - its the small electronics that each have their own power pack. Ideally to me every led lamp, settop box, alarm clock, phone, laptop would not come with a power supply box. It would just take a USB cable or similar standard. Then you could buy a good quality power supply adapter that you can reuse for lots of products - and avoid the abundance of random adapters everywhere.
- atonse 7y ago
  That is sort of happening already. A lot of devices are just using USB standard for their power supplies. I suspect that with PD, that allows even lamps to negotiate that they need more power, maybe?
lostlogin 7y ago
More than a low voltage plug (which I’d love) is the need for in wall smart plugs that have a wired connection rather than wifi. I can’t believe I’m the only person that wants this and while I’ve found a few in wall smart plugs, I’ve never found a wired one.
- paulfurtado 7y ago
  There are classic home automation systems like x10 that potentially predate wifi and offer wired solutions that use the power lines themselves for wired communication, you might want to check these out
  - kube-system 7y ago
    I remember playing with x10 consumer devices I bought off the shelf from radio shack 25 years ago. The tech was slow but very functional even back then.
  - dboreham 7y ago
    Powerline Gigabit Ethernet is a thing, but it's bordering on wireless (uses the power wiring as a "guideline" as to where its RF energy should go). This makes the network attachment unit costly and adoption low. For most applications WiFi is cheaper and more convenient. Anyone who wants really solid connectivity will lay Cat5.
    - paulfurtado 7y ago
      The use case here is turning an outlet or light on/off, so latency matters, but it requires nearly zero bandwidth (assuming that you're not talking tcp). Granted, x10 security cameras exist. x10 speaks a protocol designed for this purpose and requires a base station.
  - olyjohn 7y ago
    I've heard that a lot of these systems that transmit data over power lines have a tendency to trip the arc-fault breakers that are required in a lot of new construction.
jhoechtl 7y ago
2016
unilynx 7y ago
If none of the current plugs are usable, can we have a low-power plug standard based on PoE? Having both ethernet and low power from one socket would be perfect for IoT devices, save people from having to run Ethernet wiring themselves afterwards, and cut down on wireless spectrum use. And your 'smart fridge' would just plug into both outlets and use a relay to cut 230V if the motor doesn't need to run.
- rusk 7y ago
  Stop talking sense! Can’t you see there’s money to be made here!
- atourgates 7y ago
  Wouldn't the labor/effort cost to run and terminate Ethernet vs. 120v wiring be significantly higher? My perspective is just that of someone who's run a bit of both at an amateur level through my house, and finds terminating stupid-simple 120v wiring much, much easier than ethernet.
- mschuster91 7y ago
  While PoE can run up to 120W, it requires digital circuitry for negotiation...
gok 7y ago
> USB C meanwhile requires active cables, sockets, and devices, sacrificing any pretence [sic] of simplicity. Passive USB-C cables should be fine up to 60 watts. Beyond that you need a chip to certify safe construction but that's a good thing.
MisterTea 7y ago
We don't need DC sockets as they dont solve any problems. The stupid simple AC mains distribution system is well tested and proven. Who cares that they provide up to 3kW. The "last meter" problem is perfectly solved using AC-DC wall warts and bricks. If the power supply dies, you buy a new one and just plug it in. No electrician required. Putting things in wall or central distribution is not a solution to any existing problem and introduces needless cost and complexity. A better solution would be to get everyone on board with a single DC voltage and connector. Then we can buy larger multi socket bricks that are just AC-DC power strips. You can then add batteries and give it UPS functionality. But good luck getting everyone to agree on a single standard.
- mschuster91 7y ago
  > A better solution would be to get everyone on board with a single DC voltage and connector Why? For many things 6V is enough as it will downscale without too much loss to 5V/3V3 which is what most electronics run on... but everything that draws a boatload of power (computers, laptops, LED strips, ...) will go on 12V up to 24V, so if you want a standard it's either 12 or 24V which will introduce a lot of regulation waste in the form of heat in the device.
  - pjc50 7y ago
    Every device has a high efficiency switching regulator in it now. Regulator drop is not the issue.
  - MisterTea 7y ago
    Why? Routers, switches, small embedded computers, and a myriad of devices already use 12-24V DC and step it down internally to 3.3V or less for chip use. Laptops and even phones/tablets are no different. And conversion losses don't increase with voltage so long as you design your DC-DC converter properly. 5-6V is fine for small loads of around 10 watts but you then have to deal with line losses. A 5 m / 16 foot 24 AWG usb cable will lose 38.5% of its power from line losses at 5V, 2.5A (a measly 15 watts). If you wanted to get a low 2-3% loss for 5V, 2.5A at 5m cable length you would need 12 AWG which is massive. 24V does better but if you wanted 50+ watts you again have voltage drop issues. So in conclusion, low DC voltages are not very practical for power cable runs of over 2 meters. Though it would be nice if the last meter could be more unified with a single DC voltage and connector (my vote is for 24V). Then we can consolidate multiple devices to one strip/brick and call it a day.
kjs3 7y ago
The solar/RV/golfcart world has and entire ecosystem of standardized 12v DC power distribution and the appliances that use it if you really feel the need to have DC. Works pretty good...last year wired up a friends mountain cabin with 12v solar, batteries, inverter for AC, led lights, fans, dorm room sized DC fridge. Different manufacturers and everything popped together fine.
- iamnothere 7y ago
  Most laptops can be charged from 12V auto-style sockets as well. 12V DC is fantastic for a solar setup (vacation cabin, off-grid home, or whatever). You can still have some standard AC outlets using an inverter, but there's no reason to have lights running off of AC -- especially if you have LEDs! Since inverters cause a slow but constant power drain, it makes sense to leave them off most of the time. Edit: I also wanted to mention the amazing "3-way" fridges, which I was not aware of until looking into solar a few years ago. They can run on AC, DC, and propane, giving you an alternative if the power goes out. The RV world has tons of this stuff, and the appliances usually aren't that much more expensive. Some are even cheaper than regular appliances since they are usually more compact.
  - nybble41 7y ago
    Keep in mind that your typical RV refrigerator capable of running on AC or propane, and possibly DC, will run much less efficiently on electric power than a standard electric refrigerator. That might make them less-than-ideal for a solar + battery configuration. In an RV context one typically uses the electric mode only when connected to "shore power", where the lower efficiency is less of an issue. Propane-based refrigerators use an absorption cycle which depends on heat produced by burning the propane; in electric mode they just substitute resistive heating. A pure electric refrigerator would use a compressor-driven heat pump, which is considerably more efficient.
- ianburrell 7y ago
  What DC connector does that use? My impression is that solar panels use MC4 connectors which have separate female and male and need two connectors for DC. But there is a convention for polarity. Amateur radio has standardized on the Powerpole connector for 12V DC. Powerpole is hermaphroditic so don't have to worry about which end is plug or socket, and uses color coding for polarity.
moonbug 7y ago
go look at copper prices...
fortran77 7y ago
We don't want low voltage distribution. It's dangerous. The currents have to be MUCH higher, and actually increases fire risk.
upofadown 7y ago
Yeah, we are kind of running low on actual high power devices to plug into residential outlets these days. Those that remain are pretty much confined to specific parts of specific rooms. Various stand alone cooking things on the kitchen counter. Hair dryer in the bathroom by the mirror. The vacuum cleaner seems to be the exception and there is a tendency toward built ins. Heck, I don't know that there is even much need for high power ceiling lighting any more. Everything that people want to see with any detail is self illuminated these days. Just scatter some low power LEDs around (you don't even have to provide a way to turn them off) and you are done. If you actually want to read a paper book or do some knitting then an appropriate lamp is not going to take hardly any power as it would only have to illuminate a small area.
jhallenworld 7y ago
Crazy, USA needs higher voltage AC, not DC... People in the 240V world get to pull 3KW from their wall sockets, I'm jealous. http://wordpress.mrreid.org/2012/04/16/why-kettles-boil-slowly-in-the-us/ http://wordpress.mrreid.org/2012/04/16/why-kettles-boil-slow...
fsh 7y ago
I don't see how going to 12 V would help simplifying devices. Most chips don't run on 12 V, so one will anyway need a switch-mode power supply or linear regulators with big heat sinks inside each device. The added expense of a rectifier and mains-capable transformer is minimal. On the other hand, at least fewer people would be electrocuted by their crappy Amazon USB chargers.
errantspark 7y ago
I have to deal with this problem constantly and I haven't figured out a good solution yet. I'm not sure this is particularly meaningful in a normal mains-connected environment but as someone who's base power source is a finite amount of 24v DC, I hate eating the inversion losses when I could save ~7-16% using switching supplies off the main bus. Currently everything I have is connected up with a hodgepodge of those green pluggable terminal blocks. It's not an elegant solution but it's hard to standardize on something, especially when I have devices that run off 5, 9, 12, 24 and 48 volts. I still run an inverter most of the time (I have two, pure and modified depending on the load). I think it's possible to devise a decent solution here, I like the XLR based designs but I'm afraid of plugging things into the wrong voltage. I think maybe the good solution is to make a color-mapping for the common voltages up to 48v (past that you require an electrician to do wiring in the US iirc) and then make cables that are XLR on one end, and whatever-plug on the other end with an LED that lights up corresponding to the voltage. That way you know if your barrel jack is 12 or 5. It doesn't have to be foolproof, or even customer friendly really. People setting up DC buses to run all their electronics should be able to accept the responsibility of frying something if they give it too much juice.
205guy 7y ago
I think that with low power LED lighting, as well as all rechargeable devices, there is a case for some (not all) 12VDC sockets around the house (and cars/vans/RVs). Actually, I think mobile applications will be first: in an RV, it makes no sense to have a big inverter to take your 12V batteries to 120V AC, just to plug in wall warts to charge to camera, phone, etc. I have a friend who installed 12V in parts of his house, backed by a solar charged battery system. See my previous comment for some details: https://news.ycombinator.com/item?id=21109247 https://news.ycombinator.com/item?id=21109247 Talking to this friend, we discussed the same problem as the OP. In RVs that are wired for battery power, they use wall-mounted cigarette lighter plugs, and you can buy some small appliances that use them. They are ugly and take up too much space, it would be so much better to have a plug of a regular shape and size. Of course it has to be polarized for DC, so something like ( - | ). There is also the problem of breaking the arc in DC, so one prong needs to be longer and making contact further in so it can't arc outside the plug. Or maybe it needs some internal mechanism such as plastic slot covers that close and break the ark (like child-protected sockets have now). Anyway it definitely needs some research and design, but I think it would be cool to have a new 12VDC standard plug, then people could start designing products that use it to get the whole ecosystem started.
8bitsrule 7y ago
A DC solution is WAY overdue. Put your hand on your AC->DC converter, or your wall-wart. Above ambient room temperature? Wasted energy. "It's only 2-10 watts." Multiply by 5 units (underestimated) per 100 million households. That's >= a gigawatt. 8700+ GwH / year. That's aside from the environmental costs of making & disposing of these pernicioius devices. Time for that decades-old solution to retire.

81 points by kyancey 7y ago

> ...and incorporate a fuse to protect the appliance cable from fire. Those British BS1363, fused-mains-plug habits die hard. Lots of car barrel connectors have fuses inside. I'm not seeing much reasoning behind not using the car barrel connectors, aside from 'it was designed for cars, not as a general purpose connector'.

consp 7y ago
They break easily. Spring loaded bits (actual springs). No properly defined standard and they vary a lot. Come out easily depending on quality. Easy to contact center pole to side poles on insertion. No ability to add earth.
- Jamwinner 7y ago
  12v plugs are indeed a standard, and can be quite robust. Other than size and cost, there are no such downsides. On DC there is seldom an 'earth', gound is analougous to dc negative/neutral depending on local standard. ANSI/SAE J563 and UL2089 https://en.m.wikipedia.org/wiki/Cigarette_lighter_receptacle https://en.m.wikipedia.org/wiki/Cigarette_lighter_receptacle shows the UL standard.
  - consp 7y ago
    The case was made as a dc plug in general. Though 12V does definitely not require "earthing", you are correct about that. With earth in this case it is not the ground perse but some connection schemes (and standards) require either a third connector or open return path for DC which this connector cannot provide. Apparently they decided to make it a standard in 1994 after years of mismatching equipment all over the world, which is longer than I would have ever guessed. Interesting to see. Apparently UL "standard" does not translate well to actual standard. My experience is that most devices fail on the spring center contact, and do not fit for all cars. Anecdotal but still: even the expensive charger I have doesn't work in one car I've owned (opel) due to the misalignment of the outer contacts and it jumps out too much). It says it's UL2089 compatible though so I guess opel was at fault. There are so many "extension cords" out in the wild which hardly work or go lose after time due to bad design or because they are just a bit too wide. I own several of them and have thrown most away. The funny thing is the standard describes two sockets with differing size which is not helpful in any way and looks like a legacy of some manufacturers made into the standard. The article also mentions other bad characteristics about the connector and plug like bad contact causing high resistance which is simple due to the design but might also be present with other designs of course. I mean, it's nice it became a standard as it was in every car anyway since everybody smoked in them but there are way better solutions which do not have the problems I already mentioned and are way better solution for home appliances. If there is not yet a proper standard, why chose one which is not designed for this usage and most definitely was never designed for what it is used for today with all kinds of side effects (good or bad).
- jessaustin 7y ago
  I agree that these connectors are typically low-quality. I can't imagine ever needing to earth them, however.
mark-r 7y ago
Car connectors are ugly, oversized, and mechanically questionable. They do work though - I once used one to hook a solar cell to a 12V fan.

nickhalfasleep 7y ago

No mention of Power-over-ethernet?

mark-r 7y ago
What is the maximum power provided by PoE? Wikipedia is surprisingly vague on the subject, probably because there are multiple standards. PoE was never intended to power more than just network equipment.
- mumrah 7y ago
  I think it's something like 30W over a single ethernet cable. I'm running a few devices with PoE that are not network enabled, just conveniently located near an ethernet cable that's not near a power outlet.
- steve19 7y ago
  I am not sure how Wikipedia can be more explicit, they even have a table showing the voltages and wattages of the different standards. [0] According to that table, the latest standard, 802.3bt Type 4, can provide 71 W to the device at the end of the cable (and inject 100W into the otherside). [0] https://en.wikipedia.org/wiki/Power_over_Ethernet https://en.wikipedia.org/wiki/Power_over_Ethernet
  - mark-r 7y ago
    Clicking on the link "Power capacity limits" brings you to nothing useful. Are you looking elsewhere?
    - steve19 7y ago
      Scroll down to the table "Comparison of PoE parameters".
- vetinari 7y ago
  Depends on how you define "network equipment" :) Unifi is selling LED panels, that are powered over PoE and controlled over Ethernet.

jon-wood 7y ago

I don't get why they write off USB so quickly. It's small, it's reasonably convenient, and is almost ubiquitous already.

ocdtrekkie 7y ago
The article explains: USB A's power is too limited for a large percentage of household uses, and USB C is complicated and expensive, requiring digital circuitry to negotiate.
zwieback 7y ago
The current USB standards are great for small devices but for anything that requires more power it would be good to have something beefier, something less than the roughly 1500W a standard AC outlet provides but more than the current 15W or 20W of the typical USB port. 5V is just too low and requires a lot of compromise on the device side. I'd probably start with 12V or 24V to keep the current lower. I think there are newer USB ideas to provide something of that sort: https://www.digikey.com/en/articles/techzone/2017/mar/designing-in-usb-type-c-and-using-power-delivery-for-rapid-charging https://www.digikey.com/en/articles/techzone/2017/mar/design...

baybal2 7y ago

The telecom industry has 48 volt as a de-facto standard, bur never came to a mechanical standard. Thus you see daisy chains of mechanical adaptors in telecom closets.

kjs3 7y ago
Well...the daisy chains were the standard for mechanical connections. :-) What there never was was a connection standard safe enough to put in a house, made to be (ab)used by normal people. 48v DC as it lives in the telco world is flat out dangerous if you aren't careful.

rhinoceraptor 7y ago

It seems like USB A/C are going to be that. You can already buy outlets that have both mains and USB ports, there are even dual USB C outlets now, that can do 30 watts: https://www.amazon.com/dp/B07PTWG5DV https://www.amazon.com/dp/B07PTWG5DV

Spooky23 7y ago
The author makes the valid point that USB-A is too low power, and USB-C requires active cables. (Translation: expensive or dangerous)
- kevin_thibedeau 7y ago
  USB-A can support power delivery. The standard predates USB-C.
  - joecool1029 7y ago
    In practice I haven't seen USB PD 1.0 in the wild. Most of the non-PD charge standards signal charge rates using varied voltages on the D+/D- lines. When current manufacturers claim USB-PD they mean PD 2.0 which requires the CC line (Only included in usb-c to usb-c) to signal and set the voltage. When PD 3.0 is included, they usually call it quickcharge 4.0 or PPS.
- Johnny555 7y ago
  If you want one port that can charge multiple devices of varying needs safely, you need smarter cables. Sounds like a reasonable tradeoff. Otherwise every single cable would have to be built to handle the highest possible power delivery rate (100W for USB-C).
  - lostlogin 7y ago
    Looking at that plug and how chunky the holes are for ac power, when access is limited and you can’t see, shoving a usb c plug into the ac hole is going to happen often.

alexhutcheson 7y ago

Interesting idea, but running an extra set of cables is a non-starter. The cost/benefit analysis would never make sense for existing structures, and newly built structures wouldn't do it unless it was almost certain to become a universal standard. This is a classic chicken-and-egg problem. You would also still need something similar to a wall-wart to step down the voltage to whatever your device actually uses (e.g. from 12 V to 5 V to charge your phone), so its not clear how much benefit there would really be from such a system. Whatever specs we adopted would probably also end up not being appropriate for some future devices, so we'd probably go back to a substantial number of devices bundling their own PSUs anyway. Interesting idea, unlikely to ever be worth the cost. If wall-warts really bother you, then just invest in some wall outlets with integrated USB sockets - there are many good options on the market.

gwbas1c 7y ago
Also, the biggest non-starter is just how inefficient it is to move 12v any reasonable length. 12v domestic wiring only makes sense in very tiny small dwellings. (Think studio apartment or 3rd world country shack.) Otherwise the voltage sag and resistance makes it cheaper and more efficient to do normal 120/240 voltage with device-specific converters. (For example, if I had to run 0-gauge cable from my breaker box throughout my house to support 12v, the cost of copper alone would be prohibitive.) I honestly think standardizing on USB for devices that can use it is the best approach, given that we already have tiny AC->USB converters that don't block other plugs, and outlets with USB built-in are on the market. Furthermore, I wonder just how much we can shrink the typical wall-wart so it won't cover other plugs? (I also think we're better off trying to do a global domestic 200 or 400 volt DC standard.)

forgotmypwd123 7y ago

I always thought running low-voltage DC through a house from a single supply was doomed due to voltage drop over the distances required....

mark-r 7y ago
You could counteract that with heavier wires, but house wiring is already awkward and expensive.
zzzcpan 7y ago
Well, there is less drop with more copper, so it's more about costs. Cost of cables, DC-DC converters, power supplies and their efficiency determine optimal configuration. Probably going as high as cheap mass market DC-DC converters and PSUs allow is good rule of thumb for low voltage, so like 20-24 V. Beyond that better to go with high voltage.
- logfromblammo 7y ago
  For some reason, I feel like 48V DC over super-chunky aluminum bus bars is the only way you could avoid making the DC whole-house wiring cost less than the entire rest of the house. As I understand it, the problems that make aluminum wire strictly inferior to copper wire--expansion coefficient, heat dissipation, non-conductive oxide, and strand breakage--are less significant in bus bars. The remaining concerns would then be bimetallic junction corrosion and work hardening. Maybe a bus duct with polybenzimidazole spacers and insulation? Still sounds expensive and inefficient, though.
gmueckl 7y ago
You have to choose wire gauges carefully. A lot of cables that connect power supplies to their devices have thin wires that don't loae much voltage over the meter or so of cable. But if you woukd extend that with an equal gauge wire to some meters if length, the conmected device will likely burn out around then as well.
aivisol 7y ago
That absolutely is. You could be better with 48 or even 24 volts, but then you are out of luck if you want to power a majority of devices which are 12v. So your only option is to go for USB-A wall socket which essentially is a wall-wart hidden in your wall. I do not see a good solution here.

ethagknight 7y ago

Is "Digital Electricity" a real thing? Its billed as an alternative to AC or DC. This may be as good a place as any to ask this question, but I am a hotel developer, and we've had a few people reaching out to us trying to sell "digital electricity" that sends high voltage over cat5 (up to 2000w per the Belden materials) by essentially sending high voltage for very brief blips with the ability to switch off before any damage occurs if a short is detected. they claim it is supposed to be significantly more efficient, doesn't require electricians to run cables, and its safer. I declined... but im still curious. basically every device in the room is connected via lan to a power server. https://www.belden.com/blog/smart-building/digital-electricity-5-things-you-need-to-know https://www.belden.com/blog/smart-building/digital-electrici...

Danieru 7y ago
Oh wow, I would not want 2000w going through Ethernet. Both for the obvious electrical issues, and for the dangerous mixing of safe sockets and hot sockets. No idea how this would be more efficient. Bursting voltage will lead to higher loses versus a continuous voltage. Are they claiming efficiency thanks to a centralized AC->DC converter?
- gmueckl 7y ago
  Cat5 doesn't imply RJ45, so that confusion could be easily averted if people with brains developed that stuff. 2000w constant power transmission on a Cat5 sounds dubious, though. I don't know at what the voltage such a cable gives in and shorts wires. It would have to be pretty high to get the current to something the wire crossection can handle.
  - jacquesm 7y ago
    It's not the wattage that is going the be the problem, but either the high current or the high voltage (arcing).
pjc50 7y ago
That sounds like the sort of thing your local electrical code authority might get very upset about. It's not clear what the actual voltage is? But if it's over "SELV" ratings different rules are going to apply.

alexhutcheson 7y ago

Comments below the original post are great.

rb808 7y ago

I dont think DC wall socket is the problem - its the small electronics that each have their own power pack. Ideally to me every led lamp, settop box, alarm clock, phone, laptop would not come with a power supply box. It would just take a USB cable or similar standard. Then you could buy a good quality power supply adapter that you can reuse for lots of products - and avoid the abundance of random adapters everywhere.

atonse 7y ago
That is sort of happening already. A lot of devices are just using USB standard for their power supplies. I suspect that with PD, that allows even lamps to negotiate that they need more power, maybe?

lostlogin 7y ago

More than a low voltage plug (which I’d love) is the need for in wall smart plugs that have a wired connection rather than wifi. I can’t believe I’m the only person that wants this and while I’ve found a few in wall smart plugs, I’ve never found a wired one.

paulfurtado 7y ago
There are classic home automation systems like x10 that potentially predate wifi and offer wired solutions that use the power lines themselves for wired communication, you might want to check these out
- kube-system 7y ago
  I remember playing with x10 consumer devices I bought off the shelf from radio shack 25 years ago. The tech was slow but very functional even back then.
- dboreham 7y ago
  Powerline Gigabit Ethernet is a thing, but it's bordering on wireless (uses the power wiring as a "guideline" as to where its RF energy should go). This makes the network attachment unit costly and adoption low. For most applications WiFi is cheaper and more convenient. Anyone who wants really solid connectivity will lay Cat5.
  - paulfurtado 7y ago
    The use case here is turning an outlet or light on/off, so latency matters, but it requires nearly zero bandwidth (assuming that you're not talking tcp). Granted, x10 security cameras exist. x10 speaks a protocol designed for this purpose and requires a base station.
- olyjohn 7y ago
  I've heard that a lot of these systems that transmit data over power lines have a tendency to trip the arc-fault breakers that are required in a lot of new construction.

jhoechtl 7y ago

2016

unilynx 7y ago

If none of the current plugs are usable, can we have a low-power plug standard based on PoE? Having both ethernet and low power from one socket would be perfect for IoT devices, save people from having to run Ethernet wiring themselves afterwards, and cut down on wireless spectrum use. And your 'smart fridge' would just plug into both outlets and use a relay to cut 230V if the motor doesn't need to run.

rusk 7y ago
Stop talking sense! Can’t you see there’s money to be made here!
atourgates 7y ago
Wouldn't the labor/effort cost to run and terminate Ethernet vs. 120v wiring be significantly higher? My perspective is just that of someone who's run a bit of both at an amateur level through my house, and finds terminating stupid-simple 120v wiring much, much easier than ethernet.
mschuster91 7y ago
While PoE can run up to 120W, it requires digital circuitry for negotiation...

gok 7y ago

> USB C meanwhile requires active cables, sockets, and devices, sacrificing any pretence [sic] of simplicity. Passive USB-C cables should be fine up to 60 watts. Beyond that you need a chip to certify safe construction but that's a good thing.

MisterTea 7y ago

We don't need DC sockets as they dont solve any problems. The stupid simple AC mains distribution system is well tested and proven. Who cares that they provide up to 3kW. The "last meter" problem is perfectly solved using AC-DC wall warts and bricks. If the power supply dies, you buy a new one and just plug it in. No electrician required. Putting things in wall or central distribution is not a solution to any existing problem and introduces needless cost and complexity. A better solution would be to get everyone on board with a single DC voltage and connector. Then we can buy larger multi socket bricks that are just AC-DC power strips. You can then add batteries and give it UPS functionality. But good luck getting everyone to agree on a single standard.

mschuster91 7y ago
> A better solution would be to get everyone on board with a single DC voltage and connector Why? For many things 6V is enough as it will downscale without too much loss to 5V/3V3 which is what most electronics run on... but everything that draws a boatload of power (computers, laptops, LED strips, ...) will go on 12V up to 24V, so if you want a standard it's either 12 or 24V which will introduce a lot of regulation waste in the form of heat in the device.
- pjc50 7y ago
  Every device has a high efficiency switching regulator in it now. Regulator drop is not the issue.
- MisterTea 7y ago
  Why? Routers, switches, small embedded computers, and a myriad of devices already use 12-24V DC and step it down internally to 3.3V or less for chip use. Laptops and even phones/tablets are no different. And conversion losses don't increase with voltage so long as you design your DC-DC converter properly. 5-6V is fine for small loads of around 10 watts but you then have to deal with line losses. A 5 m / 16 foot 24 AWG usb cable will lose 38.5% of its power from line losses at 5V, 2.5A (a measly 15 watts). If you wanted to get a low 2-3% loss for 5V, 2.5A at 5m cable length you would need 12 AWG which is massive. 24V does better but if you wanted 50+ watts you again have voltage drop issues. So in conclusion, low DC voltages are not very practical for power cable runs of over 2 meters. Though it would be nice if the last meter could be more unified with a single DC voltage and connector (my vote is for 24V). Then we can consolidate multiple devices to one strip/brick and call it a day.

kjs3 7y ago

The solar/RV/golfcart world has and entire ecosystem of standardized 12v DC power distribution and the appliances that use it if you really feel the need to have DC. Works pretty good...last year wired up a friends mountain cabin with 12v solar, batteries, inverter for AC, led lights, fans, dorm room sized DC fridge. Different manufacturers and everything popped together fine.

iamnothere 7y ago
Most laptops can be charged from 12V auto-style sockets as well. 12V DC is fantastic for a solar setup (vacation cabin, off-grid home, or whatever). You can still have some standard AC outlets using an inverter, but there's no reason to have lights running off of AC -- especially if you have LEDs! Since inverters cause a slow but constant power drain, it makes sense to leave them off most of the time. Edit: I also wanted to mention the amazing "3-way" fridges, which I was not aware of until looking into solar a few years ago. They can run on AC, DC, and propane, giving you an alternative if the power goes out. The RV world has tons of this stuff, and the appliances usually aren't that much more expensive. Some are even cheaper than regular appliances since they are usually more compact.
- nybble41 7y ago
  Keep in mind that your typical RV refrigerator capable of running on AC or propane, and possibly DC, will run much less efficiently on electric power than a standard electric refrigerator. That might make them less-than-ideal for a solar + battery configuration. In an RV context one typically uses the electric mode only when connected to "shore power", where the lower efficiency is less of an issue. Propane-based refrigerators use an absorption cycle which depends on heat produced by burning the propane; in electric mode they just substitute resistive heating. A pure electric refrigerator would use a compressor-driven heat pump, which is considerably more efficient.
ianburrell 7y ago
What DC connector does that use? My impression is that solar panels use MC4 connectors which have separate female and male and need two connectors for DC. But there is a convention for polarity. Amateur radio has standardized on the Powerpole connector for 12V DC. Powerpole is hermaphroditic so don't have to worry about which end is plug or socket, and uses color coding for polarity.

moonbug 7y ago

go look at copper prices...

fortran77 7y ago

We don't want low voltage distribution. It's dangerous. The currents have to be MUCH higher, and actually increases fire risk.

upofadown 7y ago

Yeah, we are kind of running low on actual high power devices to plug into residential outlets these days. Those that remain are pretty much confined to specific parts of specific rooms. Various stand alone cooking things on the kitchen counter. Hair dryer in the bathroom by the mirror. The vacuum cleaner seems to be the exception and there is a tendency toward built ins. Heck, I don't know that there is even much need for high power ceiling lighting any more. Everything that people want to see with any detail is self illuminated these days. Just scatter some low power LEDs around (you don't even have to provide a way to turn them off) and you are done. If you actually want to read a paper book or do some knitting then an appropriate lamp is not going to take hardly any power as it would only have to illuminate a small area.

jhallenworld 7y ago

Crazy, USA needs higher voltage AC, not DC... People in the 240V world get to pull 3KW from their wall sockets, I'm jealous. http://wordpress.mrreid.org/2012/04/16/why-kettles-boil-slowly-in-the-us/ http://wordpress.mrreid.org/2012/04/16/why-kettles-boil-slow...

fsh 7y ago

I don't see how going to 12 V would help simplifying devices. Most chips don't run on 12 V, so one will anyway need a switch-mode power supply or linear regulators with big heat sinks inside each device. The added expense of a rectifier and mains-capable transformer is minimal. On the other hand, at least fewer people would be electrocuted by their crappy Amazon USB chargers.

errantspark 7y ago

I have to deal with this problem constantly and I haven't figured out a good solution yet. I'm not sure this is particularly meaningful in a normal mains-connected environment but as someone who's base power source is a finite amount of 24v DC, I hate eating the inversion losses when I could save ~7-16% using switching supplies off the main bus. Currently everything I have is connected up with a hodgepodge of those green pluggable terminal blocks. It's not an elegant solution but it's hard to standardize on something, especially when I have devices that run off 5, 9, 12, 24 and 48 volts. I still run an inverter most of the time (I have two, pure and modified depending on the load). I think it's possible to devise a decent solution here, I like the XLR based designs but I'm afraid of plugging things into the wrong voltage. I think maybe the good solution is to make a color-mapping for the common voltages up to 48v (past that you require an electrician to do wiring in the US iirc) and then make cables that are XLR on one end, and whatever-plug on the other end with an LED that lights up corresponding to the voltage. That way you know if your barrel jack is 12 or 5. It doesn't have to be foolproof, or even customer friendly really. People setting up DC buses to run all their electronics should be able to accept the responsibility of frying something if they give it too much juice.

205guy 7y ago

I think that with low power LED lighting, as well as all rechargeable devices, there is a case for some (not all) 12VDC sockets around the house (and cars/vans/RVs). Actually, I think mobile applications will be first: in an RV, it makes no sense to have a big inverter to take your 12V batteries to 120V AC, just to plug in wall warts to charge to camera, phone, etc. I have a friend who installed 12V in parts of his house, backed by a solar charged battery system. See my previous comment for some details: https://news.ycombinator.com/item?id=21109247 https://news.ycombinator.com/item?id=21109247 Talking to this friend, we discussed the same problem as the OP. In RVs that are wired for battery power, they use wall-mounted cigarette lighter plugs, and you can buy some small appliances that use them. They are ugly and take up too much space, it would be so much better to have a plug of a regular shape and size. Of course it has to be polarized for DC, so something like ( - | ). There is also the problem of breaking the arc in DC, so one prong needs to be longer and making contact further in so it can't arc outside the plug. Or maybe it needs some internal mechanism such as plastic slot covers that close and break the ark (like child-protected sockets have now). Anyway it definitely needs some research and design, but I think it would be cool to have a new 12VDC standard plug, then people could start designing products that use it to get the whole ecosystem started.

8bitsrule 7y ago

A DC solution is WAY overdue. Put your hand on your AC->DC converter, or your wall-wart. Above ambient room temperature? Wasted energy. "It's only 2-10 watts." Multiply by 5 units (underestimated) per 100 million households. That's >= a gigawatt. 8700+ GwH / year. That's aside from the environmental costs of making & disposing of these pernicioius devices. Time for that decades-old solution to retire.