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So Where’s My Low Voltage DC Wall Socket?

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Re: So Where’s My Low Voltage DC Wall Socket?

#81

Post by iamnothere »

kjs3 wrote: post #55

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.

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.

Re: So Where’s My Low Voltage DC Wall Socket?

#82

Post by upofadown »

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.

Re: So Where’s My Low Voltage DC Wall Socket?

#83

Post by pfranz »

asteli wrote: post #79
MisterTea wrote: post #46

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 existin…

Wait, that exists. USB is the standard. The UPS with standardized DC-outs is a USB power bank with integrated pass-through charging.

USB is kind of a physical standard. I have a few things like an alarm clock that uses USB, but I feel like the lower build quality is way more obvious than if it just had a wall wart.

The problem with calling USB a DC power standard is that it often doesn't work. I have a lot of trouble trying to charge my PS4 controller using random USB cables when it's attached to my PS4--I'm not even introducing an a/c adapter. I've had things like Qi chargers where I had an insufficient a/c adapter so they behaved poorly. If I'm at an airport and need a quick charge on my phone I'm definitely not going to use their USB port because if it works it'll likely charge slowly.

USB-c is worse with all of this. With a/c power it's only an issue when traveling to other countries and in many cases a physical adapter is good enough.

Re: So Where’s My Low Voltage DC Wall Socket?

#84

Post by chendragon »

asteli wrote: post #79
MisterTea wrote: post #46

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 existin…

Wait, that exists. USB is the standard. The UPS with standardized DC-outs is a USB power bank with integrated pass-through charging.

Slightly OT, but have you managed to actually find an acceptable quality USB power bank (PD/Type C or otherwise) that actually supports this "UPS mode" of operation? Most of the one I have tried cannot simultaneously output and input, or introduce a second of switching delay in between.

Re: So Where’s My Low Voltage DC Wall Socket?

#85

Post by ianburrell »

kjs3 wrote: post #55

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.

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.

Re: So Where’s My Low Voltage DC Wall Socket?

#86

Post by Gibbon1 »

NwtnsMthd wrote: post #63
ethagknight wrote: post #10

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…

My first impression is that it smells like BS but let's take a closer look. CAT6 cabling uses 4 pairs of AWG 24 wire. This type of wire typically comes with two options for insulation 250V and 600V, Let's be optimistic and use the latter. The maximum recommended current for AWG 24 wiring is 0.577A [1], as a reference PoE specs use 0.3A (if I remember correctly). Using these assumptions our maximum power transmission…

I've come around to the idea that some type of power over Ethernet is probably the correct solution for low voltage house wiring. There is an automotive standard IEEE 802.3bu-2016 which supports up to 55 watts.

The other advantage it that solves a lot of the IoT last 25 feet problem. Because it's both power and a data link.

Re: So Where’s My Low Voltage DC Wall Socket?

#87

Post by snuxoll »

laurencerowe wrote: post #68
Wowfunhappy wrote: post #61

Earlier quoted context omitted.

Wouldn't it be more efficient to have e.g. one DC power supply for the house that can power everything that needs DC power, instead of lots of individual (and likely cheap/inefficient) power supplies?

Most electronic devices require low voltage DC, so resistance losses in cabling across even quite short distances (10+ metres) would be significant. This is why DC distribution in data centres if it is used is normally 48V.

It’s also more difficult do do straight transformation on DC voltages, it can be done but the reason our power grid settled on AC was getting high voltage transmission levels down to reasonable ones for use is simple with some wound coils.

It’s really easiest to just keep everything AC until the point of use, putting a transformer and a bridge rectifier in most devices is a better solution than needing switching power supplies everywhere to convert DC voltages (or wise options like linear regulators).

Switched mode power supplies also have EMI to deal with due to the higher switching frequencies, an AC transformer runs at line frequency (50/60Hz).

Re: So Where’s My Low Voltage DC Wall Socket?

#88

Post by olyjohn »

paulfurtado wrote: post #53
lostlogin wrote: post #34

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.

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

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.

Re: So Where’s My Low Voltage DC Wall Socket?

#89

Post by ci5er »

mschuster91 wrote: post #57
MisterTea wrote: post #46

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 existin…

> 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…

Assuming you mean 5V or 3V DC, there will have to be a baseline level, then it will have to be upconverted or downconverted from the wall AC is (to whatever their baseline standard is in DC), then converted back to AC by X-converting then converting to something in AC, then downconverting to DC OR using semiconductors that used to be expensive (don't know if they still are). Seems complicated. Why not just stick with (in the US AC @ 110V - it's not like it isn't wide spread) and let all the device power adapters take care of themselves?

Or, you know, have better silicon components give us SDVC (Software Defined Voltage Control). I'm joking, but I also don't think you will save what you thik you will in TCO - Energy Savings + Device Cost differential.

I could be wrong. I have been before. And I am operating on almost zero sleep for over a day, so odds are, I could be doing to again at greater than my average error rate.

Re: So Where’s My Low Voltage DC Wall Socket?

#90

Post by lopmotr »

NwtnsMthd wrote: post #63
ethagknight wrote: post #10

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…

My first impression is that it smells like BS but let's take a closer look. CAT6 cabling uses 4 pairs of AWG 24 wire. This type of wire typically comes with two options for insulation 250V and 600V, Let's be optimistic and use the latter. The maximum recommended current for AWG 24 wiring is 0.577A [1], as a reference PoE specs use 0.3A (if I remember correctly). Using these assumptions our maximum power transmission…

There are special thicker 16 and 18 AWG Digital Electricity cables [1], so you probably wouldn't get that 2kW with CAT6 unless it's just peak power with a low duty cycle. They are rated for 300V so they might actually use close to that.

[1] https://www.belden.com/products/enterprise/copper/cable/de-c...

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