Posted on 06/20/2026 2:48:23 AM PDT by knarf
I'm not smart enough to analyze this correctly, but most of my house is operating low voltage items . . . TV's, lap tops and a ton of smaller lights and stuff that all have those little black boxes for plugs.
So you’re unintentionally AC/DC?
He was experimenting with every way possible to do it NOT with wires. But the problem there is always efficiency at an absolute minimum. How much power do you have to put in the Earth or air or whatever 10 miles from me for me to get what I need here? Unless you assume you have more power than you know what to do with (and it’s cheap and you don’t care about any of the other potential consequences of doing that) that’s not going to work.
On wires, they are energized and I pull off what I need. Some does leak to the environment, sure, but WAY less than in any Tesla scheme. And the power company is constantly monitoring demand to make sure they put more energy than needed on the line, to handle any unexpected surge in demand, but as little more as possible to limit losses.
That’s not impossible to do with DC, and as others have noted DC transmission is sometimes a smart move if the receiver is running nearly zero motors. But at the same time, converting DC voltages is WAY less efficient and WAY more complicated what converting AC voltages - and when DC power conversion equipment fails it’s WAY more expensive and time consumer to replace/repair. So we live with an AC power grid.
Tesla brought us miracles, but his notion of "through the air power" was certainly not one of them.
His AC motors, dynamos, and transformers are priceless.
He teamed up with George Westinghouse, and they did well, mostly. When they ran into hard times Tesla gave all of his stock to Westinghouse hoping to revitalize him. Westinghouse eventually recovered but Tesla never did.
Completely beside the point, Tesla and Mark Twain were both party animals who often partied together.
AC motors, generators, and transformers all originated with Tesla. He was also the creator of multi-phase power applications.
It’s 180degree two-phase into your house at your box. You are correct that it comes from only one of the three phases off the utility line, but the diagram you show CLEARLY shows that it’s 180-degree 2-phase coming out of the transformer - those three lines - the neutral and the two other phases are the three lines that come into your home. Code additionally requires you to supply a true ground/earth line, for four unique conductors in your breaker box. But that transformer is NOT in your house and you are NOT directly connected to the single phase of anything. The secondary coil separates you from the main utility line and that secondary coil provides you with 2 phases and a neutral.
It is technically wrong to say you have “one phase 180 degrees out of phase with itself.” Those are two different phases off the same coil, that’s fair to say, but they are different phases.
As I said earlier, most of your outlets are 110V/120V and wired across ONE of the TWO phases and the neutral. The ground line is taken to all of those outlets as well, which is why you have three wires in those boxes. Your 220V/240V outlets for your dryer or other tools has both phases, the neutral, and the ground wire in the boxes.
I should add that, living here on a natural outcropping in Northern Virginia, Dominion Energy wussed out when they put my line in. We live on a granite outcropping. The soil here is rarely more than 3ft deep and often barely one. When Dominion came in they *should* have brought a rock breaker and busted a trench through the granite to lay the supply line. Washington Gas did it for our gas line, and our plumbing contractor did it for our water supply and sanitary return lines. We are ~200ft off the road. So it’s a LOT of work.
As I said, Dominion wussed out. We’ve had them out here twice over the past decade since we moved in. Every time the area supervisor shows up and bitches at the work crew because he told them 10 years ago to bust the rock and they didn’t do it (and I was here to see it during construction). So, that line is laying under a few inches of rocky dirt and occasionally fails. The transformer is at the bottom of our driveway, 200ft from the house. One side of the transformer is the single phase of the three-phase main powerline that supplies our neighborhood. Our side of the transformer, separating us from the main line and also from all of our neighbors, is the two phases plus neutral that is sent to our meter box.
In every failure we have lost EXACTLY one phase. The other phase was fine. And yes, one phase failed the first time but the other phase failed the second time - because it failed in that poorly shielded conduit between the transformer and our house. If it was truly a single phase, we’d have lost power to the house. But it is two independent phases taken from separate parts of the coil, so we only lose ONE phase. We lose our dryer, the 240V machinery I have in the shop, and HALF of our outlets (to not include our AC, so AC is no problem. So I run a handful of extension cords from one part of the house to the other to keep everything that *must* run running and wait it out until Dominion fixes the problem.
They spliced the wire both times. The supervisor told me code allows them to splice each conductor once. So the next time one of the two phases fails, we get a new cable from the transformer to the house. He told me when that happens he will make damned sure they bring the rock breaker in and do it right.
And Tesla fell in love with a pigeon and thought the pigeon reciprocated.
Yes, he was smart and we owe a LOT to Tesla.
Funny - I can tell.
Can someone explain all this to me ?
I was in upper management for an electric utility for over a decade and have been serving electric utilities for over 40 years as a consulting engineer. I have also dual wired a tiny house for my oldest son in both AC and DC, so he could be “either off grid or not” in that tiny house.
Cost. Let me explain.
There are so few major and easily available DC appliances that almost all homes need to have some AC outlets. In fact, as someone who was once on my State’s Chief Electrical Engineers Safety and Code Advisory Committee, I had a very, very hard time in wiring my son’s tiny house and meeting the NEC code requirement. I talked to many people in the process of designing and wiring that house.
There are few Electrical Panels and breakers that are UL dual rated for AC or DC electric. Square D had some and I used those. There are no standard heavy duty DC electrical outlets that are UL rated (required for Code compliance and electrical inspection/approval prior to the electric utility hooking up your house or to getting an final occupancy permit). Yes there are USB plugs but their amperage is very limited and not suitable for many appliances like TV’s, toasters, microwaves, etc. You can find some of these appliances in DC at RV supply stores and boating supply stores, but they are very expensive. My son and I looked into it. Most of the lighting in the tiny house was LED, which was very efficient and inexpensive.
Our solution was to have two electrical panels one for AC and one for DC; two sets of wall wiring and outlets (one for AC and one for DC); a large battery storage system, and an inverter that allowed the battery to either run the inverters or via a switch have outside utility or generator AC power come in and either run AC stuff or charge the battery if solar was not enough.
I talked to many manufacturers, Code Electrical Inspectors, Building Dept officials, etc in my design and construction of my son’s tiny house. I can tell you that you have to do a lot of double wiring and double set of equipment to legally build such a house.
I live in Central NY State, in a small apartment building. I have a small gas furnace inside the apartment, along with A/C. I have a thermostat that I control, but we don’t have meters in our apartments. The meters for each apartment are locked in a room in the basement. Maybe about a year ago, National Grid notified us that they had installed “smart meters” in place of the old ones. I get my bill electronically and pay it every month.
Tesla died insane and penniless. A terrible tragedy. I felt rather sad reading the story leading up to his death.
By the 1920s physics had pretty much past him by!
Nay, its a center-tapped single secondary.
What you describe is almost exactly what I originally planned to do with this house (circa 2013-2014), but the number of hassles involved was just too much since it wasn’t me doing the wiring, but my general contractor. So I gave up on it. But I wanted it for relatively limited uses, as opposed to attempting to get as much on DC as possible, sort of like you are suggesting.
We have a log home, which because it’s cedar (unlike pine) has a MASSIVE thermal stability. If you open/close windows at the right time of day, use the sun intelligently, etc., moving air around efficiently to keep your house comfortable is the biggest problem to solve. So we have a lot of fans. I wanted all of the fans to be LED lighting (to further reduce heat generation) with DC motors, so I wanted them to all be wired DC. And I wanted separate DC lines to the rooms for charging phones and other battery driven appliances. I wasn’t seeking an external DC source. Just a relatively large, relatively efficient DC converter right at the AC box to provide 5/12/? DC for the things I mentioned. That way the conversion could be cheap, efficient, and centrally located.
But even just that was a sufficient pain to prevent me from doing it.
Single secondary coil supplying two independent phases. If they aren’t independent phases then they can’t fail independently - as I have I lived through twice.
A "phase" is associated with a period of a waveform, and they are each at a different phase in the time period. That is why they are named phases in the first place.
I can provide links if you don't want to look this up.
Typo
past = passed
Take a look at post #60 by fruser1.
No.
The input to the transformer is a single sinusoid with RMS 60 HZ.
The induced voltage in the secondary will also be a single sinusoid with same frequency.
Any passive load connected to it will not change that.
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