Is there or will there ever be a 48VDC outlet standard for homes & buildings?

[ChrisOlson]

Why the cheap SOB's in Sweden. I meant that humorously. However I must have missed something. If the cook top worked on 230 volts, why would you need to change anything?

Because of the difference in grounding. The European 230V neutral is the same as ground just like 120V US single phase. So if the neutral connection to ground is lost everything tied to the neutral is hot. In the US the 240V split-phase uses two "floating" lines that are totally separate from ground. That needs to be changed before you can use a European appliance on US 240V split-phase power because you are essentially plugging it in to a system where what is their neutral is now a hot wire with no connection to ground. Electrolux told my wife they could not export the range to the US without changing it.

[Sunking]

However, some things can be switched to US split-phase with very little effort. My wife bought a Swedish-made 230V Electrolux range with induction cooktop in Sweden

Why the cheap SOB's in Sweden. I meant that humorously. However I must have missed something. If the cook top worked on 230 volts, why would you need to change anything?

But I had a reason to say it. Most major appliances (high power requiring 240) desktop computers, high end AV equipment and some other things that have slipped my mind are designed to operate in the 190 to 275 volt range. That gives them international market capability. Some of the things like Ovens or things with motors have a multi-tap transformer built in. The electrician simply terminates to the right transformer tap.

And for everyone information the USA did change voltage standards by raising the single phase voltage standard. In the beginning it was just 110 volts followed by 220/110.. That was directly related to Edisons light bulb requiring 110 volts. Well technology has advanced and today the standard is 250/125.

Now for the rest of the story.

[ChrisOlson]

The 20% energy loss of transferring 48v battery to AC and the electronic products change it back to dc is just a waste.

I don't know about electronic stuff. But there's not that much loss in converting 48VDC battery to AC with a good quality inverter. I have measured our inverter at 97% efficient in the DC to AC conversion at 20% rated continuous load, which is where it runs most of the time in our house. I have a friend that lives in Alaska that has the same inverter we got, and much better measuring equipment. He measured his at 97% efficient at 1,200 watt load too.

So to put that in real-life terms, the average loss in converting DC to AC for a typical off-grid home that uses 16 kWh/day is only 480 watt-hours. I believe that if you factor in the I^2R loss of using low-voltage DC, and the extra cost of wiring and switches in the house that can handle the DC arcing, there would be no gains in using 48VDC power directly. And probably considerably more loss with heavy draw things that pull say 4 kW where you'd have to have wiring, switches and plugs capable of handling over 80 amps.

The other thing is that electronic stuff, as far as I know, runs at all kinds of different internal DC voltages. So instead of using transformer and rectifier of some sort you'd have to use DC->DC converters to change your 48VDC to the proper voltage your electronic thing requires. I doubt there'd be any gains there either.

[ChrisOlson]

Th eUSA would be in much better shape if we had used 240 instead of 120.

The 230V single phase system is much more efficient than the US split-phase 120/240V system. However, some things can be switched to US split-phase with very little effort. My wife bought a Swedish-made 230V Electrolux range with induction cooktop in Sweden and had it exported to the US. Electrolux simply changed the power transformer in it for split-phase, switched two wires around in it for the digital clock, and changed the cord to the US-style standard three-wire 240V plug. It works fine on our split-phase off-grid system and the clock on it keeps perfect time.

[Sunking]

ZoNIE appears to be talking about producing either a single ended system with 240V to ground (and no neutral, although there is a grounded conductor) or a balanced system in which both hots were 240V to ground and the grounded wire would still be a neutral.

Dave 240 AC in your home is balanced by the center tap of the secondary transformer being grounded. 120 in your home is unbalanced and the crux of many electrical interference problems encountered like HUM in your AV equipment.

Recording studios use balanced 120/60 systems with great success, and NEC has a Article dedicated to Balanced 120/60 volt systems in article 647 titled Sensitive Electronic Equipment. Back in late 1990's while working for MCI-Worldcom we used some of it in data centers to eliminate noise and bit errors that use unbalanced (grounded) signal transmission protocols like RS-232. Today with optical isolation and balanced signal protocols put an end to it. Th eUSA would be in much better shape if we had used 240 instead of 120. That is the consequence of being first to electrify. Dang Edison and his light bulb.

[warinwarin]

i lie zonie's comment and support it

[inetdog]

A technical point:
The "netural" conductor is properly one which has equal voltage to each of the other conductors used in a circuit. It may or may not be grounded.
In the case ZoNIE describes, there would be one 240V hot conductor and one grounded conductor, with no neutral since the opposite polarity 240V is not part of the scheme.

ZoNIE and Sunking are still talking about two different situations, I believe.
Sunking is describing how to use 240V loads on an existing 120/240 wiring system, and it requires adding an additional conductor to an existing 120V circuit in order to get 240V OR disconnecting the white wire from the neutral bus and connecting it to the opposite hot wire, giving a balanced 240V feed.
Other than the small matters of having to change the connectors and the NEC's unhappiness with using a white wire for an ungrounded conductor, that would work.
ZoNIE appears to be talking about producing either a single ended system with 240V to ground (and no neutral, although there is a grounded conductor) or a balanced system in which both hots were 240V to ground and the grounded wire would still be a neutral.

[Sunking]

I'm not stating it properly.

L1 and L2 go to primary on a 1:1 transformer. Secondary are still 240, but one side is tied to GND, so effectively becomes neutral. Whammo, 240V L-N.

Nope you stated it properly to me because I though that is what you meant and why I questioned it. There would be no neutral or grounded circuit conductor, just 2 hot conductors plus equipment ground, no neutral, just L1, L2, and G

[ZoNiE]

I'm not stating it properly.

L1 and L2 go to primary on a 1:1 transformer. Secondary are still 240, but one side is tied to GND, so effectively becomes neutral. Whammo, 240V L-N.

[Sunking]

Yes some rejiggering of the panel would be necessary, and the end result would be one leg and neutral, 240 et al to Neutral.

Perhaps I misunderstand what you are saying? The voltage architecture does not change. L1 to L2 = 240 L1 to G = 120, and L2-G = 120. There is no grounded circuit conductor, except from the utility and it terminates to Ground in your main panel just like it does today. All receipts and hard wired appliances are 3 wire L1, L2, and G. No current flows on G, it is there just for safety.

Lastly you can still have 120 circuits if need be. Nothing has changed that would prevent you from doing so.

[ZoNiE]

I realize the discussion is moot. Would be nice. Yes Breakers (and wire insulation) are usually rated for the max voltage present, usually 300V, sometimes 600V. I think we would end up with one voltage, not 120/240 (like on the range, Dryer, etc.) and there are many ways to do this. Yes some rejiggering of the panel would be necessary, and the end result would be one leg and neutral, 240 et al to Neutral. Probably tie the bussbars in the panel to one leg from a transformer, and the other leg becomes neutral on the load side. Replace 2 pole breakers with single pole breakers on those circuits and tie L2 to Neutral.

Would definitely create jobs, but would be about as impossible as converting the UK, It's former colonies, and Japan to driving on the Right.

Being first also gave us the lovely 525 line NTSC Television... But then PAL and SECAM sucked, But that is a whole 'nother debate. What we have now with side band channels (3.1, 3.2, etc) and varying resolution and picture format sucks ass. I miss the old analog days where changing the channel gave you an instant picture.

[Sunking]

Think again Dereck

You are welcome

.

The typical breaker found in a 120/240 panel (and essentially all residential breakers) have a voltage rating of "120/240". What that means is that they can withstand and safely interrupt 240 volts between their line and load terminals. And, as you say, in the case of an open neutral the breaker could see L1 voltage on the line terminal and L2 voltage on the load terminal, for a total of 240V across the breaker. That is the 240 part of the 120/240 rating.
But the reason for the "slash rating", with the 120 in front, is that the breaker is only tested and rated for a maximum nominal voltage of 120 volts to ground on any terminal.

So what has changed that would prevent you from using the exact same Ganged Two-Pole breakers you already have? No requirements have changed on voltages. The system is still Grounded on the secondary of the transformer, you just are not using a Neutral. As for voltage you still have the same 120 to Ground reference. The only change requirement to meet code is you have to get rid of the single pole breakers and replace them with ganged two-pole breakers.

[inetdog]

Not entirely accurate. Any breakers that can fit in a single phase breaker box is rated 240 VAC.

Think again Dereck.
The typical breaker found in a 120/240 panel (and essentially all residential breakers) have a voltage rating of "120/240". What that means is that they can withstand and safely interrupt 240 volts between their line and load terminals. And, as you say, in the case of an open neutral the breaker could see L1 voltage on the line terminal and L2 voltage on the load terminal, for a total of 240V across the breaker. That is the 240 part of the 120/240 rating.
But the reason for the "slash rating", with the 120 in front, is that the breaker is only tested and rated for a maximum nominal voltage of 120 volts to ground on any terminal. (Even though ground does not appear as a current carrying wire connected to the breaker.)

One effect of this is that you are not allowed to use a slash rated breaker on the high leg of a 120/240 three phase four wire panel. Nor can you use a slash rated breaker in a corner grounded 240 delta situation, even when the load is between one of the ungrounded lines and the grounded line. Nor can you use a two pole slash rated breaker for a line to line load of 240V in a corner grounded delta configuration.

The fully rated 240V breakers are generally used in three phase delta panels, and cost a lot more than slash rated breakers.

[Sunking]

The circuit breakers in a normal US commercial or residential panel for 120/240 or for 208Y/120 three phase are only rated for a voltage of 120V to ground. What you suggest would require replacing all circuit breakers with ones that cost upward of twice as much (and may actually require replacing the breaker panel itself.)

Not entirely accurate. Any breakers that can fit in a single phase breaker box is rated 240 VAC. They have to be in the event you loose your grounded circuit conductor from the utility, and that is a very common occurance most folks have seen at least once in their life. Ever been in a home where some lights are brighter than the others that should be the same intensity? If you do, rush out to your main breaker and turn off power to the house. Immediately call the POCO and tell them the voltage is unbalanced and your fridge is making funny noises. You will hear the POCO's truck breaks squeal outside before you hang up the phone reporting it to them

However it will never happen in the USA, so it is a moot point. Once a standard is in place, almost impossible to change. Problem for the USA was Edison himself and his damn light bulb operating on 110 VDC really screwed us up being first to electrify. Having said that there is nothing to prevent you from wiring your home with 240 VAC Balanced lines. Eliminates all the headaches of a unbalanced 240/120 grounded system. Question is where are you going to get your gizmos? Appliances no problem as most all are made to operate on 208 or 240. Computers no problem as the power supplies are designed to operate from 90 to 275 volts. Many TV's and AV systems can work 90 to 275 volts. The rest? Easy solution though, just install a 2:1 step down transformer. But all unpractical.

As for converting existing home wiring, actually pretty easy to do. You just put Black tape on the ends of all White Conductors, and move them to a circuit breaker. Green wires stay put. Then change out all your receptacles to a 250 NEMA-6-XR. Good luck finding gizmos with the right NEMA-6-XP


nema-plugs-receptacles.gif

[russ]

What you suggest would require replacing all circuit breakers with ones that cost upward of twice as much (and may actually require replacing the breaker panel itself.)
And the insulation inside light fixtures as well as the insulation in switches may well not tolerate a voltage of 240 to ground/neutral.
You would also have to provide two opposite 240V phases (for a difference of 480V) or else rewire every circuit in the building that carries both an L1 circuit and an L2 circuit with a shared neutral wire. (Called a MultiWire Branch Circuit, MWBC, or Edison circuit.)

Lots of difference between BSing and doing