Ideal Household Electrical Standards?

[DogDipstick]

Where are you located friend? This matters.

Of course wiring a house exclusively for 48v would use much more copper than currently, maybe prohibitively so.

It is not one house. It is not one house, we must, consider the price of copper, for.

It is 2.3 billion homes. On planet Earth. Do not forget that. Do you see my concern?

 

[DogDipstick]

Chalo says it all right here.

Household switches would be large, heavy, expensive, and short-lived. There would be substantial transmission losses if distribution were DC, and substantial local rectification costs if distribution were AC and residential service were DC.

Convince people to reproduce at less than replacement levels, and then we can discuss soaking extra per capita infrastructure costs.

AC is less expensive and easy to generate than DC. The distance covered by AC is more than that of the DC. The power loss during transmission in AC is less when compared to the DC. AC is the current of choice for power plants and the electrical grid as a whole. When a plug is connected to an electrical outlet, alternating current comes out, providing power to countless devices like light bulbs and refrigerators. AC is preferred for this application. Contacts would erode whenever an inductive load is place upon the proposed 48v line service, and when it was pulled from the socket. Sparks even. Low maintenance costs of high speed AC motors. So much easier to interrupt the current (ie. with a circuit breaker) due to the current going to zero naturally every 1/2 cycle. For example, a circuit breaker can interrupt about 1/20th as much DC as AC current. The modification of AC can easily be operated using particular transformers either step-up type or step-down form. The magnitude or value of alternating current can be easily reduced without the waste of extra energy. This can be performed by employing a choke coil. AC can be relatively easily and economically stepped up or down with a transformer to suit the application. AC can be easily converted to DC if required. DC cannot be wired through a transformer. So we would have to redesign ALL the microwaves, computers, refrigerators, ceiling fans, heating home systems... high power AC systems.... ect...

Dont get me wrong: Your idea basically is sound and in application: I see that we DO use DC every day, at low levels, in our homes, charging phones, running computers, and TV, and anything else that might have a switch mode power supply inside it, .. There are certainly standards written into the codes that address the distribution networks and requirements of DC current in use by consumers in the homes, and other zones, today. Certainly code for DC network power distribution. Alot of the AC, that comes into the average home, ends up as DC, inside the computer, or inside the iPhone, or used, consumed, viewing the TV, or to power the servers, that keeps the internet running.

If you want to live off grid? Yes. Go 48v for the base of your systems power source. IF you want to live out back, in the Australian woods? Yes. Go 48v. Yes yes yes, a 48v system is GREAT for a Recreational Vehicle with a solar farm on the roof: Easy hookup to powerful inverters, DC load center to handle all the fusing,: Breakers that are rated for the AC applications in teh same load center: AC and DC available and easily replenished by your solar farm and stored: Or your windmill, or your water turbine on the stream..... Yes. However, rewiring the world for the new advantages of DC is not really a feasible option. In my opinion.

 

[Hillhater]

For the people saying 100v DC is still quite dangerous, maybe you're right. Does anyone here think 48v DC would be low enough to be considered safe when accidental contact happens? Of course wiring a house exclusively for 48v would use much more copper than currently, maybe prohibitively so.

Some countries are intent on banning gas heating and cooking in domestic properties, ...those are high power appliances that can draw 5-10 kW.
A 48v supply for those would be impractical at 100-200 amps.
So at least i would think you would have to use a dual voltage system with a higher voltage for those larger services loads.
But that effectively negates the concept of low voltage safety in domestic situations !

 

[Username1]

Show me. Cite a notation: a reference. Your source, so we are on the same page, please. I might be able to explain your misinterpretation. Based on your rudimentary experience in the application under discussion I see you are missing some certain knowledge on the subject.

I'm pretty sure it's hard to find a copy of the electrical code without paying for it. Are you saying this 80% rule doesn't exist in North America? If I'm wrong please explain.

However, rewiring the world for the new advantages of DC is not really a feasible option. In my opinion.

Of course it's not feasible. Like I said in the first post, it's just a fun thought experiment if a country was starting fresh.

AC was clearly useful in the past for durable, "dumb" induction motors. At this point they can be replaced by switched reluctance or other DC motors. All light bulbs including incandescent work on DC. Home AC isn't needed except that it's our current standard.

Some countries are intent on banning gas heating and cooking in domestic properties, ...those are high power appliances that can draw 5-10 kW.
A 48v supply for those would be impractical at 100-200 amps.
So at least i would think you would have to use a dual voltage system with a higher voltage for those larger services loads.
But that effectively negates the concept of low voltage safety in domestic situations !

True, which is why I originally suggested 100v. At 100v you'd need 4 gauge wire to supply 10 kW, so you really can't go any lower when powering an entire house on a single voltage.

Assuming everything was spec'd properly, surely this would still be significantly safer than 120v/240v AC. Nobody is saying to intentionally grab the wires, but if it makes accidental fatal shocks exceedingly rare then that's a huge improvement.

 

[fechter]

The main reason AC is popular is you can use a transformer. Transformers are needed for long distance transmission lines to get the voltage very high. Otherwise, you'd need very fat wires to carry the current or have huge resistance losses. I guess the other reason is you can run a 3 phase induction motor right off a power line. A really big one, if you want. With DC, you need an inverter to run an induction motor.

 

[99t4]

OP opened an interesting debate, similar to the historical (over 130 years ago) "Battle of the Currents," involving Edison (DC), Westinghouse (AC), and Tesla (the person)(poly-phase AC induction motor, the "killer app").

Also involving much intrigue, lawsuits, collusion, patent wrangling, patent conflicts, business mergers, financial mergers, early versions of hostile takeovers, fearmongering smear campaigns, cruelty to animals, maneuvers to link AC to the electric chair (to sway public opinion), appeals to death by electric chair (as inhumane), sparking/burning/smoldering linesman in plain sight by NYC lunchtime crowds.

Edison eventually lost interest in promoting his DC system as he became more involved with his dream of extracting iron ore by crushing rock in huge rollers (never really panned out).

"In 1908 Edison said to George Stanley, son of AC transformer inventor William Stanley, Jr., 'Tell your father I was wrong', probably admitting he had underestimated the developmental potential of alternating current." (from https://en.wikipedia.org/wiki/War_of_the_currents). Great read.

 

[Username1]

Speaking of Edison, I just read that he chose 110v DC because he considered it the upper limit for a safe voltage. That said, I also read that's just the voltage his light bulbs happened to work best with.

What's interesting is Edison's system used 110v everywhere from powerplants to house. This meant multiple small powerplants every kilometer or so. I guess the original usage was basically just light bulbs, which means the powerlines could transmit enough power. Obviously high voltage power lines are necessary for our modern power usage, whether AC or DC, with localized or centralized power plants.