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Comment by dghlsakjg | Hacker News Reader

You do realize that the grid runs at a completely different voltage than what is actually delivered to standard residential service, right?

It is entirely possible to get three phase, high-voltage power in North America, it just isn't run to individual houses unless specifically requested.

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400V three phase is wired to all houses at least here in Finland. All 3 phases are wired to the electric box and then that splits phases to normal sockets and for lighting etc. Ovens use three phases and detached houses usually have separate 3-phase plugs outside for running eg. heavy construction tools, like cement mixer and such. Oh right and sauna stove also needs all 3 phases obviously.

Even apartments have that full 3-phases, but just for plugging in the oven and the sauna stove.

There really isn't a huge advantage for 3 phase unless you are doing high-power DC rectification or trying to run a motor.

The US grid is basically 3-phase everywhere, but it's neither needed nor cost-effective to run it into the home.

Now, the 400V part is different. That would require less copper (but with a safety cost).

Currently probably biggest advantage is electric car charging. It is easy and cheap to add high power fast charger when there is already 3 phases available.

400V between phases so 230V per phase. Safety is provided by making plugs not expose contacts while half plugged. US plugs are really unsafe compared to plugs used in most of the Europe.

And safety provided by having much stricter control and requirements on the whole house electrical system.

Also power tools, with 400v plugs you can go to much higher wattages on circular saws, planers etc.

The last transformer between houses and the grid is 440v three phase. As I understand it the distribution networks all look pretty much the same, it’s only the last mile that differs. And thus consumer electronics.

If you want to run a machine shop, it’s a pain but not impossible to get 440 three phase wired straight through to your business. But consumer “heavy” motors and induction stoves run on two phase 230V.

Its everywhere in Europe. I haven't seen nor heard about say a single oven not plugged into 400V. I've lived in 4 different countries in east & west, all the same. Even when traveling around a bit, I see those special plugs in convenient places, where you may expect to plug something powerful for some heavier work.

Anything high power, you go for this plug. I'd imagine car charging would also benefit from this but not personally in that market yet.

This HN thread is the first time I learned about 400 V to homes in Europe. My oven is 220 V. I just checked the manual. All my house is 220 V. I live in Italy.

Plugs are usually Shuko for high power appliances (washing machine) and two smaller pins for low power (phone chargers.)

By the way, Italy traditionally had a three pin in a line high power plug but more and more appliances are coming with Shuko plugs so wall socket are either bi-standard or just Shuko now.

The 400V is between phases. 230V is between a phase and ground. Ie, you get 3 wires (phases) of 230V from the 400V connection.

Btw, Europe standardized at 230/400V in the nineties. In Czechia we switched from 220V to 230V in 1993. Not sure when Italy did, but probably around the same time.

"Standardized". The allowable voltage for power is normally something like 6%. When they switched from the mis-mash of 220 and 240V to 230V, they specified the allowable voltage range was wide enough to encompass both of those, including the allowable voltage range for 240V. So largely it was just "Everything is 230V now, and try to make sure new stuff is actually 230V".

Yes. “Standardising” to 230V +/-10%, allows for 220/230/240V +/-6% (the previous standards used in different countries) to all coexist without actually changing any equipment.

My UPS most of the time reports just under 240v.

> detached houses usually have separate 3-phase plugs outside for running eg. heavy construction tools, like cement mixer and such.

Is this sort of use common in Finland? It seems like kinda a waste of money and materials to install the infrastructure to allow everyone to run heavy construction equipment off their home's electrical supply.

I can't talk about Finland, but in Central Europe it's pretty common as there is a culture of house building.

In the US, a developer typically buys an entire neighborhood's worth of land and builds a bunch of houses there to sell to individuals.

Over here, the individuals will typically buy their own small plot of land and then have a house built there according to their specifications. You need to be able to run heavy construction equipment to do so.

How esle is the home going to get renovation work and upkeep done?

Since you need three phase 380V for the sauna and the kitchen anyway, and probably for the ground or air heat pump too... it doesn't cost almost anything to run a cable from the electrical box and installing a three phase socket.

This shows a 32A 400V socket costs under 10 euros: https://www.taloon.com/voimapistorasia-pinta-bals-101-3pne-3...

It is more efficient. Going from 4 wires to 5 is not a big deal if you then can have triple power. Or you can use thinner wires thus less material overall.

The split phase is two lives, neutral and ground. 3-phase is 3 lives, neutral and ground.

In Europe the wiring in the ground is always 3 phase, they just connect only 1 phase. You can upgrade to 3 phase for a fee and then a guy comes and switches it over. They don't need to open up the streets or anything like that to get you 3 phase power.

Not always - I live in the countryside in the UK and we seem to have single phase sadly.

Tends we live in a row of cottages and the phase is split between us so every third house is on the same phase

Pretty sure that’s standard for the UK

It is. I remember when we had a power cut and when I went outside I could see that only a single phase had been lost - every third house had gone dark, the rest remaining lit.

I reported it and it was sorted pretty quickly.

Nearly everywhere in UK has only a single phase supply, it's how the grid in this country is designed.

Houses in the UK are connected to a single phase, but a three phase supply is available if it's needed — the cable is in the street, though digging a new trench to connect to it is often costly.

Larger users are presumably connected with three phases by default — that primary school in the middle of the housing estate, the retirement home that has several lifts, not-tiny shops, the small block of flats etc.

You can request it all you want in North America, but you probably won't get it. A three phase converter is way more likely.

You can get it if you're willing to pay for it, but you may not like the quoted price.

Haha, I can't get it at all here. It's not a matter of paying an absurd price that will get you a PhasePerfect for 10% of it. It's a matter of it just not being available at all.

Have you really asked? Generally it is possible if you pay, but expect to pay $100,000+ to get it. Most neighborhoods don't have the right wires to you pay paying for all new poles and wires to your neighborhood.

That said, a few cities/states don't allow 3 phase to residences in their building code. However most do allow it, and so it is just a matter of convincing the power company to run it.

If I had a periodic need for three phase power on-site, I would just purchase (or rent) a generator that can provide this style of output.

I think most home shops use phase converters, either rotary phase converters or variable frequency drives. With those you can create a third phase to run machines that need it, although obviously you won't have as much power available to you.

My own shop uses: https://www.phasetechnologies.com/products/phase-converters/...

It's nice because there's no motor to worry about maintaining and the machines can run at full power.

And of course, an alternatives is to have a battery bank as well with inverters - which means you can get your amps - but only if you're not running 24/7. You'd have to let the grid (or solar) charge you up.

In CA it's just a matter of checking a box, then they put a transformer on the PG&E pole to match your voltage reqs - the wire to your pole is $90. The transformer can run in the thousands probably up to 10k. Of course, if your area can't handle the voltage * amperage requested, they may deny it or ask for about 10k per new pole to install in the ground.

That said you just pay that once, after that you have your rate.

A lot of people have odd power requirements - but usually not residences. Farms typically get 400V for greenhouse fans, for example.

Far more common for 3-phase motor loads in residential areas (already an unusual requirement) is the point use of a rotary phase convertor or (more commonly now) variable frequency drive to run the 3-phase motor from the existing split-phase supply.

In the US, the amount of three phase electricians that will work at a Residential home and not charge you an arm and a leg for it is vanishingly low, almost certainly not worth it.

That's sort of a chicken-and-egg problem. If residential three-phase electricity were commonplace, electricians would all happily handle it at their standard rates, your air conditioners and refrigerators would all be running on it.

No? It clearly takes more training and has more liability since the consequences of a mistake are more serious. The average billable rate would inevitably be higher regardless.

What kinds of mistakes are harmless at 120V @ 100A vs 400V @ 30A?

Touching 120V with dry skin is nearly always harmless. 240V is considerably more exciting.

Maybe it's a little different for just a converter, but mine didn't have a problem installing a Phase Perfect and running a few three-phase outlets for it.

Wait, there are special electricians for three-phase in the US, is this like an additional certification or are the normal ones scared of three phases?

Not sure if there's an additional certification, but it would not surprise me at all that an electrician here would not want to work on a home with an unusual setup that they're not particularly familiar with.

Electricians specialize. Resi guys do residential and rarely to never handle 3 phase. I do commercial and light industrial because heavy industry isn't around here and I despise doing resi work. Three phase is usually run everywhere by the power co and a transformer (pole pig) converts to single phase near the residence.

There isn't. But residential electricians are specialists. Then there are commercial and industrial ones, etc, etc.

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