Really all residential connections in the US are 220V split phase. The nice thing about split phase is that it is easy to well... split and run two linked 110V circuits, so most houses will have a few 220V items(ovens, airconditioner) and the rest wired half with phase A the other half with phase B. all of our consumer items expect this 110V
As to why split phase.... I am not really sure. Really, I wish a three phase residential had become normal instead. All the advantages of split phase but now your motors don't have to suck. I have heard a three phase residential connection is common in some parts of Germany, lucky bastards.
One interesting side note is how the US last mile distribution layout is different than germany. The US uses a lot more smaller transformers, really one per street. while germany uses fewer larger transformers, one per neighborhood. not sure which one is better I bet the german layout is more efficient. but I will note it is a lot easier to keep spares and change out a small transformer.
> Really all residential connections in the US are 220V split phase
Really all modern residential connections in Europe are 400V three phase electric power, capable to immediately power an electric motor without the need of capacitors.
No matter how you put it, the US residential power grid is conceptionally lagging.
How many residential appliances benefit from three phase, and is the benefit outweighed by the additional cost of more copper for the additional wires?
For example, a common big motor that needs a starter capacitor is a HVAC unit. Usually the copper to run those is extremely expensive, on the order of hundreds of dollars. Adding an additional wire may add an additional hundred dollars or more. By comparison, starter caps are quite cheap. $20 for a HVAC sized one. That also isn't counting any of the costs of three phase infrastructure for breakers etc.
That also isn't even counting that many appliances are moving to inverter based technologies that don't utilize induction motors at all, such as induction hobs. Or, many appliances with no benefit from extra phases (resistive heating devices such as ovens, dryers, toasters, etc).
The answers and comments on [0] would seem to suggest that's not true.
Seems the power grid has the capability of delivering three phase power, but many (most?) homes in quite a few European countries don't actually have all three phases delivered.
> No matter how you put it, the US residential power grid is conceptionally lagging.
That's only the case if you believe the US is "missing out" on all that much with our split-phase setup. I don't think that's the case, really. Even for EV charging, using the 240V across the -120V and 120V lines is more or less fine. We've been doing the same thing with our electric stoves, water heaters, etc. for quite some time now.
Certainly there are some things you can do with 3-phase that aren't really feasible with split-phase, but I don't think most people living in the US care too much. It's true that those who do are probably upset about it, though!
Also consider that the US power system is trivially 3-phase! We just don't wire all those phases to homes, as we a) don't generally see the need to, b) chicken-and-egg problem suggests that most people wouldn't be able to use it anyway, since appliances made for the US wouldn't be able to take advantage of it.
400v 3-phase in a house is crazy to me. I was hit with 480v once (someone cut my lockout and turned the power on). That stuff will outright kill you unless someone else is around to help.
One of my favorite things about US residential power is that 120v is far less dangerous when homeowners (or worse, kids) accidentally do something they shouldn't.
Neither of these benefit from a 3-phase motor aside from not having to swap out $10 start/run capacitors, the conductors would be #8 for 3p and #6 for split phase.
You can easily power a three-phase motor on a split-phase service with a VFD.
You can get three-phase power in certain locations at a residence, but you pay a monthly connection charge and commercial rates.
Good induction cookers and electric car chargers, heat pumps and things really do often require the high voltage for best function so this high voltage three-phase is also becoming standard for the energy transition.
I had to upgrade my electricity meter and switch box (even though as mentioned three-phase to the house is already standard) recently in order to accommodate planned environmental upgrades.
UK is in Europe and yet this isn't true here. Nearly all residential properties in this country are wired for single phase 220V. It's true on the continent though.
The split phase arrangement comes from Edison's DC systems. For large installations they found out that the losses were unacceptable and solved thet by running the lighting on 220V with sets of two 110V bulbs in series, usually combined with some somewhat funky wiring scheme in order to even more reduce the required wiring cross-section (it is somewhat reminiscent of later British ring mains construction and strikingly similar to various arrangements for powering long LED strips). This is also the reason why it is somewhat common for the US commercial lighting to use 220V.
Three phase for residental connection is pretty much a standard everywhere with 230/400V system. Only small flats and really small houses get single phase. This is because the 230/400V output of the larger distribution transformer is inherently threephase and this gets distributed to essentially all the points of connection and the only reason why there are single phase residental connection is that they are slightly cheaper (both in terms of fixed monthly payment for capacity and in terms of initial installation costs). While in US the input to the typical residental pole/pedestal mounted local distribution transformer is already single phase, so you cannot really get three phases without running additional wires to the substation (and probably also having you own dedicated distribution transformer) and thus in a residantal area you are simply stuck with split-phase.
> solved thet by running the lighting on 220V with sets of two 110V bulbs in series
A related tip is to build a "dim bulb tester" to help you diagnose short circuits on mains-powered equipment. I have a traditional incandescent lightbulb in a porcelain socket wired in series with an outlet (and a switch). A non-shorted load will tend to work pretty well as the cold/cool incandescent bulb is fairly low resistance in series with the load. A shorted load will light up the light bulb brightly but not trip any breakers, allowing the opportunity to do some troubleshooting on the bench.
I've also used this concept several times to find short circuits in house wiring. Put the dim bulb tester in series with the circuit that's shorted and then, using a non-contact voltage tester, find where the measurement on the NCVT changes. That's likely where your short is.
In building such a device, you're on your own liability-wise; please don't be dumb.
Another thing Americans miss out on - the "boost" function on modern induction stoves. Since the oven usually gets one phase and the cooking fields get two dedicated phases of the 400V lines, you can use "boost" to steal power from the other phase. Water boils even faster than in a tea kettle!
> I have heard a three phase residential connection is common in some parts of Germany, lucky bastards.
German here. Virtually all houses built after the 60s will have at least 3x63A @ 230V (L-N) / 400V (L1-L2/L2-L3/L3-L1) AC. Individual flats/apartments/studios from before the 90s will usually have a single phase 32-40A uplink, so in a 12-unit house you'll have four flats wired to L1, four to L2, and the last four to L3 to ensure even load across the phases. More recent builds that don't have gas stoves any more will have a 3x40 connection to allow for powerful electric stoves and ovens.
The US also uses a different primary network configuration, typically running a three-phase network as main primary with single phase primary laterals. The pole-mount single-phase transformers then turn this single-phase into split-phase LV for consumer use. One consequence of this is that adding three-phase to a property that doesn't have it already is really hard - you need to upgrade the LV service connection, the transformer, and the MV lateral (since the MV lateral is only a single phase). Compare that to the European system which has three-phase distribution transformers and then runs three-phase LV past every property. In some places like Germany, the standard is to provide three-phase to every property, in others like the UK, standard is single phase service connection but... it's easy to add three phase since the other two phases are only a few metres away, I understand the Dutch standard is to run all three phases to the property but only connect as a standard (you have to pay for the upgrade).
I think in both cases, for urban and suburban areas it is standard to run the MV feeder as a normally open ring so that in case of a fault in the primary, parts of the system can be run from the other end of the ring by remotely operated automatic breakers. What I don't know is whether US systems do that at the level of the main primary only or also on the laterals.
> The US uses a lot more smaller transformers, really one per street. while germany uses fewer larger transformers
I am from Spain and living in the US and something that was shocking to me about it is that here, at least where I lived, these last transformers are hanging from poles and every now and then I can hear an explosion and it is one of them blowing up.
I have no idea but, maybe being exposed like they are here in the US makes them more vulnerable to weather conditions and that makes them explode? Or maybe it simply is that in Spain they also explode but the fact of not being that close to residences makes it harder to hear it.
Transformer explosions are rare. Unless you can produce statistics saying otherwise it is safe to assume they happen as often in both countries (per something, the US obvious has far more transformers given larger population and area, and thus should have more total)
> but I will note it is a lot easier to keep spares and change out a small transformer.
In my neighborhood, about once a year there's a loud pop, or quiet bang, and a bunch of houses lose power. The electric company will fix it pretty quickly.
I think that it's performing selection pressure on the unlicensed squirrel electrician population.
Growing up in the sticks, I'm pretty sure there was an unlicensed trade school for squirrels in the area. Pretty much once a year, we'd need a replaced transformer from one of these unlicensed squirrel electricians. I never charted the timing of the year this would happen, but now I wonder if aligned with the start of a new class.
I was a little surprised that my neighborhood must have some redundancy. A year or so ago a transformer on a pole two doors down from us popped, and our power actually didn't go out.
In Denmark, most homes have 3 phases of 240 volts, along with neutral. (and protective ground, of course)
More power in less copper. Most items do fine with 240 volts, but high-power items like ovens and electric cars can use two or three. Also, we have the CEE 5P plugs, which look awesome and allow you to draw a lot of juice from a single point.
How many residential devices actually ought to contain a three-phase motor running at fixed frequency? (And I mean now, in 2023, not in 1990.)
I can think of three, sort of:
1. A well pump, pumping from a high-producing well, into a tank or pond at the surface, where the pump is sized to efficiently pump somewhat less than the well’s production.
2. A pool or pond pump which, by some miracle, has been correctly sized for the system, and which, by some other miracle, is more appropriate in the application in question than an Intelliflo VSF or similar pump.
3. HVAC fans. But these are usually pretty small, and better systems usually use ECM motors.
I have all three of these and absolutely none of them contain (or will contain at any point) a three phase motor. All three of these use variable speed motors in my house. I suspect even more will moving forward as well. So honestly three phase is pointless as I just need "power" to drive the variable speed controller system. My hottub has fixed speed 220 pumps but its old. I suspect newer systems would be moving to variable speed as well.
I think your pretty spot on that most people do not need 3 phase, even in the limited cases you mentioned. =)
> I have heard a three phase residential connection is common in some parts of Germany, lucky bastards.
Czech Republic switched to 3 phase 380V in 1919. I guess the transition DC -> 110V AC -> 3 phase ~400V went quick everywhere in the world, just in US they did not do the last step.
The cool thing is in Switzerland with the T15 / T25 plug you can use from a small 230V LN plug, 230V LNPE plug or a 3x400V 3LNPE plug. You see this often in workshops. I think this is unique in the world.[1]
Also the 3xT13, 3 plugs where everywhere else in the world is just one plug. [2]
I've worked at utilities with both systems. The UK system, which also has three phases to most every customer, is way better. And I'm an american power engineer.
By the way, the US nominal voltage is 120 volts. I don't know why everyone refers to 110 Volts.
You are correct about the last mile. Since single phase is distributed so often, the utility distribution engineer has a lot more work to balance things. In the UK and other networks, there is no single phase distribution.
When talking about the voltage of US residential service, and the devices that use it, 240 and 220, and 120 and 110 are functionally the same. The house theoretically has 240v and 120v power, but voltage may sag throughout the home's wiring, and some outlets will a real voltage reading lower than 240/120.
Every computer power supply I've seen in the last 10 years or so is basically rated for input as something like '100-250v, 50-60hz. That way they work on virtually any power grid anywhere in the world, it's just a matter of having the right female IEC to male <local whatever> power cable.
Most power supplies do 100-240V so they can be used in multiple countries. You might be able to find cable to connect it to 240V plug, or could wire one up. But there would be no advantage to using 240V.
The only advantage for 240V is higher power. All desktop PSUs top out at 1800W because of the 120V 15A limit. There are server PSU that have higher power limits that would need to use 240V to reach the higher limit.
EDIT: I stand corrected by the comments below. Readers Ignore most of what I said on this comment. I was mistaken.
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You have some misunderstandings in your comment.
Unless it is a very old construction or a smaller home, houses in the US as well as most of americas are provided with one or more phases derived from the secondary of a step-down transformer in Y configuration (3-phase, 1-neutral => 4 wires).
So, for a small apartment, maybe you'll get a single phase wire plus the neutral, or more commonly 2-phase wires plus neutral, up to the full 3 phase wires plus neutral.
The phases are usually 220V between then and 120 between any individual phase and the neutral connector.
Europeans don't have this convenience because the step-down transformers give homes 3 phases in a delta configuration (so, 3 phase wires, no neutral wire), so, they only have the 220V between any two-phases.
Also, split and wall ar-conditioning systems are almost universally bi-polar with a capacitor, in Europe, Asia, or the Americas. As well as most refrigerators, freezers and other similar appliances. In the past we used to have driers that would be multi-polar, but it was never very common.
It is more usual to have tri-phase motors in bigger motors, like those used in central AC units. And HVAC systems in the US accordingly will usually require an upgrade if your home is not wired with 3-phase plus neutral, unless it is a small HVAC. Electrical vehicle charges also usually require 3-phase.
People are confusing what they have the electric outlets inside their homes with what gets from the street into the distribution panel in the house. Most power outlets inside a house are bi-polar connectors (so, in europe, they can only be 220 phase-to-phase, and in the US and most of the American continent, they can be either 220 phase-to-phase or 110 V phase-to-neutral. The third connector in a domestic outlet is usually the ground, not another phase or the neutral.
The three-phases are usually split between different circuits at home, trying to ensure that the load is somewhat evenly split, but at the outlets, you'll have either phase-phase, or phase-neutral, and this is the same in Europe or America, but the americans have the flexibility to have phase-neutral dipole with half the voltage that europeans don't have.
Regarding having smaller step down transformers close to homes instead of a single giant unit, we need to remember that keeping the low-tension wires short is more efficient, and this is achieved by having the transformers closer to consumers, instead of having a giant transformer distant from the consumers.
I am not an American, and I know that a lot of things in America could be more efficient, but power distribution to residences is probably not something were europe have an edge over the US.
> Unless it is a very old construction or a smaller home, houses in the US as well as most of americas are provided with multiple phases in Y configuration (3-phase, 4 wires, one neutral).
> So, for a small apartment, maybe you'll get a single phase wire plus the neutral, or more commonly 2-phase wires plus neutral, up to the full 3 phase wires plus neutral.
> The phases are usually 220V between then and 120 between any individual phase and the neutral connector.
I am an American - an electrical engineer in the Midwest - and I was on roofs last week after a tornado came through our town, working with the distribution panels. What you said is not correct. Homes get 240/120 nominal line voltage, or 220/110V at the load, 180 degrees out of phase, plus a neutral.
That is not the same as two phases plus the center conductor of 3-phase Y.
In industrial facilities, it's reasonably common 208V 3-phase in a Y configuration, with three wires each 120 degrees out of phase with each other. This is typically used for lighting circuits, because it's 120 phase to ground and can use commodity bulbs and ballasts. More commonly, machines will run off 480V 3-phase, which is 277 phase-to-ground.
So your first statement is correct for apartments and condos. Typically 3 phase comes into the building then each unit gets 2 phases and a neutral ran to them. This actually works out to 208V phase to phase but phase to neutral is still 120v. Appliances like cooktops and ovens are definitely less power when ran off of 208v. For single family homes you only get a single phase, a center tapped transformer steps down the voltage to 240V leg to leg so coming into the house is two legs from the transformer and the center tap which is your neutral. Some really large houses sometimes get 3 phase but that is very rare. Usually large houses will just bump to 400 amp service.
US voltage is 120 V (240 V phase to phase), not 110 V. And while 115 V is within service tolerances specified by ANSI C84.1 (114 V to 126 V), that's not the nominal value.
It's a bit of a pet peeve of mine. We've been standardized on 240/120 since 1967, and still many people insist on saying 110 and 220. It hasn't been 110V since well before 1967, either -- it was increasing over time before they locked it at 120.
Its been 120VAC in the vast majority of the US since quite some time like the 1940's - 1960's.'
A minority are still 115-120VAC but very few still at 110VAC or even 110VDC.
But 110V line voltage is still too common of a misconception still lingering overseas.
This can be seen in some power transformers which are built overseas with multiple primary windings intended for international use. Often these will step-up or step-down the incoming line voltage to the working level correctly using the 240V primary when 230-240V is actually powering the transformer through that winding. But when used in the USA with the 110V primary, the transformer powers the working circuit with almost 10 percent higher voltage than the engineers thought they were going to get.
Thanks, I'm in canada and I know we're 120, I was wondering if there was some reason the US was different and I'd just never heard about it. Iirc Japan, at least part of it, may actually be 110.
This is partially done to compensate for terrible wiring. Lots of people are fond of using small wires and going long distances leading to a lot of voltage drop. They often send 125v or so from the transformer which is 123-124 at the panel, 120 v or so at the receptacle, and >100v after someone decides to run something on a few hundred feet of #18 extension cord.
It's about looking at supply vs demand. Electrical devices are often labeled by the minimum voltage they require to operate. 110 V is commonly used because the device can operate reliably on a 120 V distribution system.
Power supplies are rated for 100V because that's the voltage in Japan. Though the tolerance would probably be useful for running a really long US extension cord.
Laptops and other electronics are often the same between North America and europe, just with a different plug, thus the wide tolerance. For anything with a motor or coil this probably won't work
I have a question for you as a Brit. I live in an Asian household (my wife is Asian). We have a hot water boiler, as most Asian households do. It keeps 4L of water at "tea" temperature at all times (after boiling it).
When we want tea, we just fill up the cup with the already boiled and ready water. It's super efficient because it's super insulated so it barely takes any energy to keep it hot after it's been boiled.
Why don't Brits (and other tea drinking cultures in Europe) do this?
I'm not sure how much difference this makes, but when I use the hot water boiler at work, the tea definitely tastes slightly off compared to using a kettle at home. But it's also possible the hot water boiler at work is not producing hot enough water.
The hot urn cannot be more efficient than boiling the correct amount of water each time.
The limiting factor is the specific heat capacity of water. If daily consumption is 2l, you have to put in the joules to raise 2l to boiling, either way. If you have heat losses during the day, there's your inefficiency.
Some do. It's become a popular addition to a middle class kitchen. All offices have them.
As to why Asian households have it and we don't, I think it's simply that we have been boiling water in kettles since the stoves ran on coal, and the electric kettle is just an upgrade of that same old system
Not to mention the age of our housing stock. The Asian households you refer to, when were their homes built? I'm guessing much more recently, comparatively speaking.
What is tea temperature for you? As I understand it black tea which Brits drink should be made with water at close to boiling (100 C) while green tea should be made with water at 80 C.
My pet peeve in the US is ordering a cup of tea and getting a cup of cooling water and a teabag by the side. Fine for herbal or green tea but terrible for black tea.
At least in the German-speaking market there exist said solutions, but they are not very common (yet?). I believe keeping 4L at near boiling temperature is still less efficient than individually heating and it takes less than a minute with 3kW.
Has anyone ever made a battery-powered kettle with significantly higher power than can be pulled from a wall outlet? Modern lithium batteries can deliver many kilowatts of power, and given that the total energy needed to boil the water is basically fixed, the battery size requirements might be pretty reasonable. I wouldn't be surprised if boiling water in 15s is possible even on a 120v American outlet.
At 3.6V and 45A, each battery should output 162 watts. Rounding to 150 watts, we'd need 20 of them to make 3 kilowatts. So $100 worth of batteries.
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Question #2: How long will they last? Long enough to boil water?
At the 45-amp discharge rate and with 4.2 amp-hour capacity, it should take 4.2/45 hours = 6 or 7 minutes to discharge them.
By my math, it takes 335 kilojoules to heat a liter of water from 20°C to 100°C. A 3 kilowatt kettle should be able to do it in 335/3 = 112 seconds.
So the batteries should be able to boil water around 3 times before discharged.
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Those calculations are for running on battery alone. Since you can get 1500W out of an American 120V outlet, you could make a kettle that draws 1500W from the wall and boosts it with 1500W of battery power. (I'd use two heating elements.) Then you only need $50 of batteries.
The kettle is going to be a bit heavy, though. The batteries are 70g each, so 20 of them is 1.4 kg. Also, I don't know much batteries heat up when cranking out 45 amps, but I bet the answer is a lot, and you may need active cooling and/or thermal shutoff.
Now I realize that what I really want to build is a kettle with two 3kW heating elements. On a UK ring main, I can plug the two elements into two neighbouring sockets and still have headroom before I blow the breaker. I can cut my time-to-tea from 45 seconds to 22 seconds!
It's certainly possible; whether it makes any economic sense at all is a different matter. I can't imagine much of a market for a device like this. Basically you're proposing a relatively complicated device (compared to a simple tea kettle, though modern ones have a handy auto-shut-off feature) for the sole purpose of boiling water a little faster. Americans aren't big tea drinkers in the first place, so it's hard to imagine many would pay 5x-10x as much (guessing) for a fancy battery-boosted tea kettle just to boil water a little faster. I suppose it's possible though; Li-ion batteries are pretty commonplace these days.
I think it's certainly possible. FWIW car batteries can often support 1000A especially those for large diesel engines. They aren't meant for continuously loads or deep cycles though. Marine batteries may be able to overcome this.
It's probably the most remarkable difference. It's interesting how houses are wired for 10-20A of current everywhere, regardless of voltage. You'd assume that since European houses are mostly wired for 16A then US houses would be wired for 32A (or the other way around, if you know US houses wired for 15A, you would assume the European wires for 8A). But curiously that's not the case.
Ignoring the UK with their 13A/30A rings for a moment, since their wiring is unique.
Largely this is resolved by US houses having a lot more circuits. My bathroom has a dedicated 20 amp (2.4 kW) circuit for the outlets and a separate 15 amp (1.8 kW) circuit for the lights. Every bedroom in my house has its own 15 amp breaker. The kitchen has 3 20 amp breakers for different wall outlets, a 15 amp breaker for the lights, then a 30 amp 240v (7.2 kW) breaker for the cooktop, and a 20 amp 240v (4.8 kW) breaker for the oven.
For the a typical US house the standard feed into the house is 200 amps at 240v. So 48kW of power coming in we just segment it down a lot more.
32A capable wiring is much more expensive. And if we are being honest, the number of modern appliances that need more than 1800W is very small outside of the kitchen. If it were a common problem people would be installing 6-20 receptacles, but that's pretty rare. I have exactly one, and it's in the garage.
Resistive losses are related to current (I^2 R), so you need thicker wires to deliver the same power at a lower voltage. I guess it was decided that it wasn't worth the expense.
If you increase Ampere you must increase the width of the cable, or it will overheat. If you increase Voltage you must increase the insulation around the cable.
As an American, I have a faucet at my kitchen sink that will give me water at 195F. That takes care of nearly all my needs for truly hot water. When I do need the last few degrees to get a roiling boil, my induction cooktop has a 3700W burner that will do it in a hurry.
> As an American, I have a faucet at my kitchen sink that will give me water at 195F.
The building code for the province of Ontario (Canada) states that delivered water cannot be higher than 49C (120F); §7.6.5.1. Maximum Temperature of Hot Water:
We have the same. The system has a high-end water filter which then exits into a split, one outlet of which goes to a room-temp tap and the other into the heater, so we have both filtered "cold" and hot water.
Now that I have a 5kw induction cooktop I can boil water incredibly fast. However I’m not sure it’s that useful since it’s not like I’m standing there watching it, so whether it’s 1 min or 5 min doesn’t matter.
I have a really old infrared range that takes 20+ minutes to boil a pot of water. Believe me when it takes that long it does matter. (it is on the list to replace, but there are higher priorities in this house to fix first, and only limited budget)
If you use an induction hob, a classic stovetop kettle (the kind that whistles!) will allow you to boil water quickly. The large ring on my last hob was 3kw.
The power companies know this, and time their cutovers from Europe with the end of Eastendets, which is when people turn on their kettle for a cup of tea before making dinner.
(I’m not sure if that’s still a good hint, but it certainly was ten or so years ago.)
I would like to see a US electric range with Schuko outlets and 16A GFCI breakers on the side, but that probably violates too many electrical codes.
Schuko makes the most sense because it's unpolarized, so appliances don't expect a neutral leg. You still have the 50/60 Hz problem, but something like a kettle probably won't care.
Or there could be a countertop "Schuko dongle" that attaches to the screw terminals on the back of an existing range, if it weren't for those meddling codes...
Though in practice, the key to boiling fast is to use less water. A 1500W kettle with 500 mL minimum fill is totally reasonable for cup of coffee/tea.
I have 20 amp sockets in my kitchen (as all newly built housing has, really) but there are no 20 amp kettles on the market. I wish I could get that extra 600 watts or power :(
I'm struggling to understand how the British grid works, as an Italian transplated to UK. IIRC in Italy most residential circuit breakers have a limit of 3.3 kW, so it's pretty easy to trip it with a few appliances running, and we don't even use electric kettles that much.
Yet in Britain, with a 3 kW kettle, I've never managed to trip it, with a combination of laundry machine, electric oven, microwave, dishwasher. Is there no circuit breaker limit?
When when the UK was rebuilding the housing stock post WW2, ring mains (or circuits) were designed to both increase consumer safety and to combat the anticipated post-war copper shortage. This design allows for high integrity earthing and greater power per unit of floor area for a given cable size than a radial circuit. Most white goods (Dishwashers, washing machines, etc.) are locally fused and often ovens are on a separate ring with their own fuses in the distribution board. This is why you rarely trip the circuit. It can be done though.
Post WW2 for newly built small flats, ring mains were designed to save on copper (as it was in shortage). The intention was to allow for 3-bar electric fires to be operated as 13A loads, and be moveable between rooms.
Rings are more complex to test, and have nasty failure modes. I'd argue that they should only be used in said small flats, and that 20A bus/radial runs should be used in larger builds. i.e. any modern house, rather than a flat. Said run the supplying all of the sockets in any given room, it does though require a larger "consumer unit".
The rings have a 30A (or now 32A) at the "consumer unit" (distribution fuse box) with two cables running in a loop around all sockets in the circuit. The cables have traditionally been 2.5mm, and open clipped, so rated at around 27A (based upon preventing overheating).
Hence when operating properly, the wiring in the circuit can carry 54A, the circuit is fused at 30A (or 32A) to protect the cable, and an individual load is limited to 13A (being the highest cartridge fuse commonly available).
There may be several circuits, and they all have independent breakers. Certainly, an electric cooker/oven will be on its own circuit as it has higher requirements.
Then, standard ring circuit is 32A, and individual sockets are limited to 13A (via fuse in plug). So you will need to have 2 kettles on on the same circuit and then add a third device pulling not an insignificant amount of power (32 - 2x13 = 6A) before the breaker trips. This will be safe if the ring circuit is not faulty as they are usually wired with two 2.5mm2 cables (two because it's a ring) that have a standard rating of 24A each...
> in Italy most residential circuit breakers have a limit of 3.3 kW
Wait, really? That’s seriously underpowered, though I guess if you never need electric stoves or heating it could be somewhat usable. An ex-Soviet big-city apartment building will usually support 40A (~9kW) per apartment, and in France I had the impression that the values were similar—except for student dorms, which are supplied and wired like apartment buildings despite the density of occupants being 3x that or more, because apparently the builders could not into engineering and the uni authorities find it easier to blame the occupants (yes, I’m still a bit salty about that).
In a perfect world a ring circuit is a clever invention - it offers a circuit that can safely deliver about 7.3kW with hardly any more copper than normally could deliver about 4.6kW.
However in practice they have a hidden failure mode - if you break the ring they will carry on working apparently without problem except it’s quite possible that you now have overheating cables in a wall somewhere. In the real world houses are full of changes (both DIY and professional) that inadvertently break the ring and it’s not at all uncommon to see in a house with even modest refurb works having been done.
Going from memory but this is an artifact of WW2. There was a copper shortage so they decided to save on wiring costs by running only a few high current circuits through the whole house. The appliance plugs are instead fused as any fault in the appliance would happen after the plug. This is why UK plugs are all fused - they are the final branch circuit over current protection device. I actually like the idea.
> I'm struggling to understand how the British grid works
Like most things, understanding the history helps. The ring circuit was designed because it uses less copper than other methods - and copper was scarce after WWII. Almost all other design decisions either come directly from the idea of saving copper, or the idea that there are not enough Legos to step on so the electric plug must substitute.
That sounds almost as bad as what we have to deal with in the US!
I live in an early 20th century apartment in San Francisco and I quickly learned not to run my 1.8kW kettle at the same time as my 1.2kW microwave as it would consistently trip the power.
More annoying is when the fridge compressor motor starts up while running either as that also trips the power.
The difference really is night and day between a US and UK kettle.
The worst part of the British system though (although I don’t think this has anything to do with voltage, IDK) is there is nowhere to plug-in your razor, hair clippers, hair dryer, toothbrush, curling iron, etc. etc.
That's building regulations, sadly. Sockets need to be multiple meters from splash zones, but there's an exception for shaver sockets, which have their own transformer, limited amps, and have a plug that looks very similar to the non-grounded EU plugs.
No, we can still do that -- I have a dual-voltage shaver point next to my bathroom sink with my electric toothbrush plugged in.
There's a famous, common 20VA fixture by Legrand with a distinctive symbol. I asked an electrician about this last year. Most electricians will still fit them.
It won't supply a hairdryer or a pair of curling tongs, probably. Not that you really want such things in a bathroom or without an earth pin.
As an American, I find the boiling speed of 1L in an electric kettle to be remarkably fast compared to drip coffee or boiling on the stove. Granted, that says more about my expectations than the actual speed.
Generally I use an insulated 4L kettle that stays warm all day, so it heats up very quickly when needed and somewhat negates the issue.
An induction stove is still really inefficient at heating water, compared to an electric kettle with the resistive element in the water and 3kW of power.
Are people actually using induction stoves for tea, though?
For me, a big selling point of the kettle is that you don't have to clean it and stow it after every use, so I would still use the kettle even if it was slower (maybe no longer for pasta or when cooking in general though)...
edit: I guess you could just get a teapot that is induction-compatible, didn't think of that.
My in-laws have fried three different induction hobs boiling a kettle on them. Good quality brands too, they just can't seem to cope with frequently being set to max.
> USA uses 230-240 VAC, too. The only difference is that we ground it in the center, creating "split" phases, reducing the peak voltage relative to ground and making it easier to interface low-power loads. But high-power loads (stoves, water heaters, clothes dryers, etc.) operate across the full voltage, reducing the current required.
They generally don't blow at the rated current. I've reliably used a 13A fuse on something that draws 16A for a while when starting up and never had a problem. Obviously RCDs etc are more accurate, but wired / cartridge fuses are always under-rated, in my experience.
It's possible to ask an electrician to install a 240V outlet in the US and then get a UK-spec kettle. You just need to make sure the kettle doesn't care about the frequency difference (probably not), and the hot-hot vs hot-neutral difference (also probably not).
Possible, but the outlet will have a different plug. Most window air conditioners use that type of outlet, and some garages will have it for hobby equipment. I don't think you can legally install a UK (or EU) outlet in the US even though everything that plugs into it would be just fine on our 240V power (a few clocks won't work right, but they won't be harmed or harm anything)
Somehow I've never considered my home kettle too slow in the US, even though I have tea probably 2-3 times a day. And there's an instant hot water machine at our office, so it's not like I've gotten used to slowness.
On the hot beverage topic, I'm jealous that the espresso gear in Europe is a little cheaper/faster. The motors that drive coffee grinders and the heaters that heat up water in the boilers work a lot easier/faster.
I used to sympathize with this take until I bought a Zojirushi water boiler, which provides instantaneous hot water. Now even a faster kettle is a downgrade in experience.
Light bulbs in the early 1900s were first designed for lower voltages, and the grid slowly raised things over time, but at some point they couldn't go any higher because it would start blowing things, so they were 'stuck' in the 110-120V range.
The 50Hz and 60Hz is quite noticeable. I'm used to hearing mains hum at 50 Hz, so hearing it at 60 Hz sounds a little different. (You can sometimes hear it in audio recordings etc).
There was a video recently where YouTuber diodegonewild was fixing old power supply, he turned it on, listened to it and said "the transformer has DC offset on it, because it's humming at 50Hz, the magnetostriction doesn't care about polarity, healthy transformer hums at 100Hz, I think one of the diodes in bridge rectifier is bad" and he was right.
I'm not sure there is a good answer, beyond "the US stuck with Edison's 110V, Europe went with 230V because it's cheaper". Both 110V and 230V are reasonable choices. And of course technically the US primarily uses 230V split between two phases. But Europe mostly uses 3-phase 400V, with each phase delivering 230V (because phases are 120° offset to each other), so then we are just talking about 230V vs 400V, and two vs three phases.
Are they, though? With modern appliances, power requirements are going up and 110V is struggling to keep up. One example would be an induction hob.
I know that technically US homes can access 230V but they aren't wired for that, probably 99% are wired just for 110V except for maybe a few special lines.
US Power is typically 240v split-phase, a single phase, not two phases. The transformer is 7200v to 240v. The Neutral line to your house is center tapped on the transformer giving you 120v from Hot to Neutral and 240v from Hot to Hot. I have L14-30 and L5-30 outlets throughout my house and property for example which lets me run higher voltage/amperage workloads more easily. My workshop has an isolation transformer which is 240v primary and 120v secondary. This allows me to run 80A of 120v "stuff" in my workshop but it's a 40A 240v load from the perspective of the main panel in the house.
So, not only is the UK 230v, it's also wired in a ring (i.e., your circuit isn't a branch from your junction box, it's a full loop). So, for a given power capacity, you can use much less copper.
UK fixed wiring circuits, unlike those found in almost all other countries, make widespread use of ring circuit designs, as well as radial circuit designs often seen in other countries. (This was one of the recommendations of the Electrical Installations Committee, convened in 1942 as part of the Post War Building Studies programme, which in 1944 determined that the ring final circuit offered a more efficient and lower cost method to support a greater number of sockets.[6]) It continues to be the usual wiring method for domestic and light commercial socket and device wiring in the UK. Lighting circuits, which typically have lower power requirements, are usually radially wired, confusingly sometimes called "loop" wiring.
So, the why is: More power, less copper, and that's really useful when you're resource constrained because someone has declared war on you and is blockading your coast, or you're recovering from that.
Safety was one significant concern. 230-240V is more likely to stop a person's heart. 220 is available in most US homes for specific cases where it is more practical.
Speaking from experience, I don't think it is uncommon for a person to have been electrically shocked at some point in their lives --- often when they were a child.
Maybe common in the US. Europe takes plug and outlet design more serious (as a consequence of 230V), and while the UK plug and continental Europe's Schuko plug are very different both make it basically impossible to accidentally shock yourself.
And to me this seems most obvious answers. With possibility that you had other resistive loads at that voltage already sold. And people would be rather gross if they had to replace them.
The one explaining that Edison's DC system they were competing with, in the US, was using ~100v DC. And the public disinformation campaign characterizing AC as unsafe. Including attacking anything higher than approximately 100v as unsafe. That seemed like it answered the question to me.
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As to why split phase.... I am not really sure. Really, I wish a three phase residential had become normal instead. All the advantages of split phase but now your motors don't have to suck. I have heard a three phase residential connection is common in some parts of Germany, lucky bastards.
One interesting side note is how the US last mile distribution layout is different than germany. The US uses a lot more smaller transformers, really one per street. while germany uses fewer larger transformers, one per neighborhood. not sure which one is better I bet the german layout is more efficient. but I will note it is a lot easier to keep spares and change out a small transformer.
Really all modern residential connections in Europe are 400V three phase electric power, capable to immediately power an electric motor without the need of capacitors.
No matter how you put it, the US residential power grid is conceptionally lagging.
For example, a common big motor that needs a starter capacitor is a HVAC unit. Usually the copper to run those is extremely expensive, on the order of hundreds of dollars. Adding an additional wire may add an additional hundred dollars or more. By comparison, starter caps are quite cheap. $20 for a HVAC sized one. That also isn't counting any of the costs of three phase infrastructure for breakers etc.
That also isn't even counting that many appliances are moving to inverter based technologies that don't utilize induction motors at all, such as induction hobs. Or, many appliances with no benefit from extra phases (resistive heating devices such as ovens, dryers, toasters, etc).
Seems to me that the tradeoff is worth it.
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.
Seems the power grid has the capability of delivering three phase power, but many (most?) homes in quite a few European countries don't actually have all three phases delivered.
> No matter how you put it, the US residential power grid is conceptionally lagging.
That's only the case if you believe the US is "missing out" on all that much with our split-phase setup. I don't think that's the case, really. Even for EV charging, using the 240V across the -120V and 120V lines is more or less fine. We've been doing the same thing with our electric stoves, water heaters, etc. for quite some time now.
Certainly there are some things you can do with 3-phase that aren't really feasible with split-phase, but I don't think most people living in the US care too much. It's true that those who do are probably upset about it, though!
Also consider that the US power system is trivially 3-phase! We just don't wire all those phases to homes, as we a) don't generally see the need to, b) chicken-and-egg problem suggests that most people wouldn't be able to use it anyway, since appliances made for the US wouldn't be able to take advantage of it.
[0] https://electronics.stackexchange.com/questions/625353/is-3-...
One of my favorite things about US residential power is that 120v is far less dangerous when homeowners (or worse, kids) accidentally do something they shouldn't.
-1/2 to 3/4 HP furnace fan - 3 to 5 ton AC unit
Neither of these benefit from a 3-phase motor aside from not having to swap out $10 start/run capacitors, the conductors would be #8 for 3p and #6 for split phase.
You can easily power a three-phase motor on a split-phase service with a VFD.
You can get three-phase power in certain locations at a residence, but you pay a monthly connection charge and commercial rates.
Not just conceptually == reliability is lower than that of its peers: https://www.statista.com/statistics/268155/ranking-of-the-20... (if you don't have a statista account, US is at the bottom of this list at 98.6)
State level data: https://www.eia.gov/electricity/data/eia861/
I had to upgrade my electricity meter and switch box (even though as mentioned three-phase to the house is already standard) recently in order to accommodate planned environmental upgrades.
Not the case in the UK.
Three phase for residental connection is pretty much a standard everywhere with 230/400V system. Only small flats and really small houses get single phase. This is because the 230/400V output of the larger distribution transformer is inherently threephase and this gets distributed to essentially all the points of connection and the only reason why there are single phase residental connection is that they are slightly cheaper (both in terms of fixed monthly payment for capacity and in terms of initial installation costs). While in US the input to the typical residental pole/pedestal mounted local distribution transformer is already single phase, so you cannot really get three phases without running additional wires to the substation (and probably also having you own dedicated distribution transformer) and thus in a residantal area you are simply stuck with split-phase.
A related tip is to build a "dim bulb tester" to help you diagnose short circuits on mains-powered equipment. I have a traditional incandescent lightbulb in a porcelain socket wired in series with an outlet (and a switch). A non-shorted load will tend to work pretty well as the cold/cool incandescent bulb is fairly low resistance in series with the load. A shorted load will light up the light bulb brightly but not trip any breakers, allowing the opportunity to do some troubleshooting on the bench.
I've also used this concept several times to find short circuits in house wiring. Put the dim bulb tester in series with the circuit that's shorted and then, using a non-contact voltage tester, find where the measurement on the NCVT changes. That's likely where your short is.
In building such a device, you're on your own liability-wise; please don't be dumb.
Sounds like an exciting day when one of your bulbs burns out!
German here. Virtually all houses built after the 60s will have at least 3x63A @ 230V (L-N) / 400V (L1-L2/L2-L3/L3-L1) AC. Individual flats/apartments/studios from before the 90s will usually have a single phase 32-40A uplink, so in a 12-unit house you'll have four flats wired to L1, four to L2, and the last four to L3 to ensure even load across the phases. More recent builds that don't have gas stoves any more will have a 3x40 connection to allow for powerful electric stoves and ovens.
How are loads balanced to phases in a standalone house?
I think in both cases, for urban and suburban areas it is standard to run the MV feeder as a normally open ring so that in case of a fault in the primary, parts of the system can be run from the other end of the ring by remotely operated automatic breakers. What I don't know is whether US systems do that at the level of the main primary only or also on the laterals.
I am from Spain and living in the US and something that was shocking to me about it is that here, at least where I lived, these last transformers are hanging from poles and every now and then I can hear an explosion and it is one of them blowing up.
I have no idea but, maybe being exposed like they are here in the US makes them more vulnerable to weather conditions and that makes them explode? Or maybe it simply is that in Spain they also explode but the fact of not being that close to residences makes it harder to hear it.
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In my neighborhood, about once a year there's a loud pop, or quiet bang, and a bunch of houses lose power. The electric company will fix it pretty quickly.
I think that it's performing selection pressure on the unlicensed squirrel electrician population.
It was manufactured in 1959!
Over here (large country in South Asia) it's three phase by default.
You can get single phase upon request, provided it's a really really small house, shop etc.
It sounds like a crossword puzzle. :)
Not some parts. It's common in all parts of Germany - and I think even common on the whole EU.
More power in less copper. Most items do fine with 240 volts, but high-power items like ovens and electric cars can use two or three. Also, we have the CEE 5P plugs, which look awesome and allow you to draw a lot of juice from a single point.
I can think of three, sort of:
1. A well pump, pumping from a high-producing well, into a tank or pond at the surface, where the pump is sized to efficiently pump somewhat less than the well’s production.
2. A pool or pond pump which, by some miracle, has been correctly sized for the system, and which, by some other miracle, is more appropriate in the application in question than an Intelliflo VSF or similar pump.
3. HVAC fans. But these are usually pretty small, and better systems usually use ECM motors.
I think your pretty spot on that most people do not need 3 phase, even in the limited cases you mentioned. =)
Czech Republic switched to 3 phase 380V in 1919. I guess the transition DC -> 110V AC -> 3 phase ~400V went quick everywhere in the world, just in US they did not do the last step.
Also the 3xT13, 3 plugs where everywhere else in the world is just one plug. [2]
[1] https://de.m.wikipedia.org/wiki/SN_441011
[2] https://hager.com/de-ch/katalog/produkt/wh22730700k-ka-eb-st...
By the way, the US nominal voltage is 120 volts. I don't know why everyone refers to 110 Volts.
You are correct about the last mile. Since single phase is distributed so often, the utility distribution engineer has a lot more work to balance things. In the UK and other networks, there is no single phase distribution.
I've heard for some wet construction locations they'll set up 120V split phase with two 60V legs, to keep the potential to ground smaller.
The only advantage for 240V is higher power. All desktop PSUs top out at 1800W because of the 120V 15A limit. There are server PSU that have higher power limits that would need to use 240V to reach the higher limit.
Generally anything that has an IEC power connector will support running at 240v (but beware, you may need to flip a switch).
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You have some misunderstandings in your comment.
Unless it is a very old construction or a smaller home, houses in the US as well as most of americas are provided with one or more phases derived from the secondary of a step-down transformer in Y configuration (3-phase, 1-neutral => 4 wires).
So, for a small apartment, maybe you'll get a single phase wire plus the neutral, or more commonly 2-phase wires plus neutral, up to the full 3 phase wires plus neutral.
The phases are usually 220V between then and 120 between any individual phase and the neutral connector.
Europeans don't have this convenience because the step-down transformers give homes 3 phases in a delta configuration (so, 3 phase wires, no neutral wire), so, they only have the 220V between any two-phases.
Also, split and wall ar-conditioning systems are almost universally bi-polar with a capacitor, in Europe, Asia, or the Americas. As well as most refrigerators, freezers and other similar appliances. In the past we used to have driers that would be multi-polar, but it was never very common.
It is more usual to have tri-phase motors in bigger motors, like those used in central AC units. And HVAC systems in the US accordingly will usually require an upgrade if your home is not wired with 3-phase plus neutral, unless it is a small HVAC. Electrical vehicle charges also usually require 3-phase.
People are confusing what they have the electric outlets inside their homes with what gets from the street into the distribution panel in the house. Most power outlets inside a house are bi-polar connectors (so, in europe, they can only be 220 phase-to-phase, and in the US and most of the American continent, they can be either 220 phase-to-phase or 110 V phase-to-neutral. The third connector in a domestic outlet is usually the ground, not another phase or the neutral.
The three-phases are usually split between different circuits at home, trying to ensure that the load is somewhat evenly split, but at the outlets, you'll have either phase-phase, or phase-neutral, and this is the same in Europe or America, but the americans have the flexibility to have phase-neutral dipole with half the voltage that europeans don't have.
Regarding having smaller step down transformers close to homes instead of a single giant unit, we need to remember that keeping the low-tension wires short is more efficient, and this is achieved by having the transformers closer to consumers, instead of having a giant transformer distant from the consumers.
I am not an American, and I know that a lot of things in America could be more efficient, but power distribution to residences is probably not something were europe have an edge over the US.
> So, for a small apartment, maybe you'll get a single phase wire plus the neutral, or more commonly 2-phase wires plus neutral, up to the full 3 phase wires plus neutral.
> The phases are usually 220V between then and 120 between any individual phase and the neutral connector.
I am an American - an electrical engineer in the Midwest - and I was on roofs last week after a tornado came through our town, working with the distribution panels. What you said is not correct. Homes get 240/120 nominal line voltage, or 220/110V at the load, 180 degrees out of phase, plus a neutral.
That is not the same as two phases plus the center conductor of 3-phase Y.
In industrial facilities, it's reasonably common 208V 3-phase in a Y configuration, with three wires each 120 degrees out of phase with each other. This is typically used for lighting circuits, because it's 120 phase to ground and can use commodity bulbs and ballasts. More commonly, machines will run off 480V 3-phase, which is 277 phase-to-ground.
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US voltage is 120 V (240 V phase to phase), not 110 V. And while 115 V is within service tolerances specified by ANSI C84.1 (114 V to 126 V), that's not the nominal value.
A minority are still 115-120VAC but very few still at 110VAC or even 110VDC.
But 110V line voltage is still too common of a misconception still lingering overseas.
This can be seen in some power transformers which are built overseas with multiple primary windings intended for international use. Often these will step-up or step-down the incoming line voltage to the working level correctly using the 240V primary when 230-240V is actually powering the transformer through that winding. But when used in the USA with the 110V primary, the transformer powers the working circuit with almost 10 percent higher voltage than the engineers thought they were going to get.
Japan uses 100V and 50/60 Hz depending on where you are in the country.
For example, my laptop charger is rated for 100-240V, which is not uncommon.
Power supplies are rated for 100V because that's the voltage in Japan. Though the tolerance would probably be useful for running a really long US extension cord.
https://www.electrical4u.com/rms-or-root-mean-square-value-o...
When we want tea, we just fill up the cup with the already boiled and ready water. It's super efficient because it's super insulated so it barely takes any energy to keep it hot after it's been boiled.
Why don't Brits (and other tea drinking cultures in Europe) do this?
Always use freshly drawn (filtered if possible) cold water in the kettle. Tea loves oxygen as it helps the flavour develop.
Most of us are guilty of the following... looking at the kettle seeing there is some old, used water in there and simply re-boiling.
If you keep re-boiling the water in the kettle, it loses all of its oxygen and you’ll be left with a really flat cup of tea.
If you boil the kettle with fresh water, you’ll have a delicious cup of oxygenated tea that tastes divine.
https://twinings.co.uk/blogs/news/how-to-make-a-cup-of-tea-p...
I'm not sure how much difference this makes, but when I use the hot water boiler at work, the tea definitely tastes slightly off compared to using a kettle at home. But it's also possible the hot water boiler at work is not producing hot enough water.
The limiting factor is the specific heat capacity of water. If daily consumption is 2l, you have to put in the joules to raise 2l to boiling, either way. If you have heat losses during the day, there's your inefficiency.
As to why Asian households have it and we don't, I think it's simply that we have been boiling water in kettles since the stoves ran on coal, and the electric kettle is just an upgrade of that same old system
Not to mention the age of our housing stock. The Asian households you refer to, when were their homes built? I'm guessing much more recently, comparatively speaking.
My pet peeve in the US is ordering a cup of tea and getting a cup of cooling water and a teabag by the side. Fine for herbal or green tea but terrible for black tea.
Because it is better to boil the right amount of water to the precise temperature when you need it, as it takes virtually no time.
I kid, but there's something about "fresh" water probably?
=-=-=
Question #1: Can we get 3 kilowatts of power out of some lithium ion batteries?
There are high-current versions of lithium batteries. Conveniently, they're widely available because they're used for vaping.
I found a battery that looks reasonable (https://www.18650batterystore.com/products/molicel-p42a). Its stats: 4200 mAh capacity, 3.6V nominal, 45A continuous discharge, and retail cost $4.99.
At 3.6V and 45A, each battery should output 162 watts. Rounding to 150 watts, we'd need 20 of them to make 3 kilowatts. So $100 worth of batteries.
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Question #2: How long will they last? Long enough to boil water?
At the 45-amp discharge rate and with 4.2 amp-hour capacity, it should take 4.2/45 hours = 6 or 7 minutes to discharge them.
By my math, it takes 335 kilojoules to heat a liter of water from 20°C to 100°C. A 3 kilowatt kettle should be able to do it in 335/3 = 112 seconds.
So the batteries should be able to boil water around 3 times before discharged.
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Those calculations are for running on battery alone. Since you can get 1500W out of an American 120V outlet, you could make a kettle that draws 1500W from the wall and boosts it with 1500W of battery power. (I'd use two heating elements.) Then you only need $50 of batteries.
The kettle is going to be a bit heavy, though. The batteries are 70g each, so 20 of them is 1.4 kg. Also, I don't know much batteries heat up when cranking out 45 amps, but I bet the answer is a lot, and you may need active cooling and/or thermal shutoff.
https://twitter.com/sdamico/status/1592553611879673856?s=20
Ignoring the UK with their 13A/30A rings for a moment, since their wiring is unique.
For the a typical US house the standard feed into the house is 200 amps at 240v. So 48kW of power coming in we just segment it down a lot more.
The building code for the province of Ontario (Canada) states that delivered water cannot be higher than 49C (120F); §7.6.5.1. Maximum Temperature of Hot Water:
* https://www.ontario.ca/laws/regulation/r04023
An exception is given for dish— and clothes washer outlets.
In the UK I put the water on then while it’s boiling get a mug and tea bag and then the kettle is boiled very soon after.
In the US I generally wonder off as the kettle takes a couple of minutes longer.
https://en.wikipedia.org/wiki/TV_pickup
Schuko makes the most sense because it's unpolarized, so appliances don't expect a neutral leg. You still have the 50/60 Hz problem, but something like a kettle probably won't care.
Or there could be a countertop "Schuko dongle" that attaches to the screw terminals on the back of an existing range, if it weren't for those meddling codes...
Though in practice, the key to boiling fast is to use less water. A 1500W kettle with 500 mL minimum fill is totally reasonable for cup of coffee/tea.
In practice, NEC code likely prohibits you from doing this.
Yet in Britain, with a 3 kW kettle, I've never managed to trip it, with a combination of laundry machine, electric oven, microwave, dishwasher. Is there no circuit breaker limit?
Rings are more complex to test, and have nasty failure modes. I'd argue that they should only be used in said small flats, and that 20A bus/radial runs should be used in larger builds. i.e. any modern house, rather than a flat. Said run the supplying all of the sockets in any given room, it does though require a larger "consumer unit".
The rings have a 30A (or now 32A) at the "consumer unit" (distribution fuse box) with two cables running in a loop around all sockets in the circuit. The cables have traditionally been 2.5mm, and open clipped, so rated at around 27A (based upon preventing overheating).
Hence when operating properly, the wiring in the circuit can carry 54A, the circuit is fused at 30A (or 32A) to protect the cable, and an individual load is limited to 13A (being the highest cartridge fuse commonly available).
Have a look here: https://www.diydoctor.org.uk/projects/cablesizes.htm
Then, standard ring circuit is 32A, and individual sockets are limited to 13A (via fuse in plug). So you will need to have 2 kettles on on the same circuit and then add a third device pulling not an insignificant amount of power (32 - 2x13 = 6A) before the breaker trips. This will be safe if the ring circuit is not faulty as they are usually wired with two 2.5mm2 cables (two because it's a ring) that have a standard rating of 24A each...
Wait, really? That’s seriously underpowered, though I guess if you never need electric stoves or heating it could be somewhat usable. An ex-Soviet big-city apartment building will usually support 40A (~9kW) per apartment, and in France I had the impression that the values were similar—except for student dorms, which are supplied and wired like apartment buildings despite the density of occupants being 3x that or more, because apparently the builders could not into engineering and the uni authorities find it easier to blame the occupants (yes, I’m still a bit salty about that).
In a perfect world a ring circuit is a clever invention - it offers a circuit that can safely deliver about 7.3kW with hardly any more copper than normally could deliver about 4.6kW.
However in practice they have a hidden failure mode - if you break the ring they will carry on working apparently without problem except it’s quite possible that you now have overheating cables in a wall somewhere. In the real world houses are full of changes (both DIY and professional) that inadvertently break the ring and it’s not at all uncommon to see in a house with even modest refurb works having been done.
I live in an early 20th century apartment in San Francisco and I quickly learned not to run my 1.8kW kettle at the same time as my 1.2kW microwave as it would consistently trip the power.
More annoying is when the fridge compressor motor starts up while running either as that also trips the power.
https://www.homedepot.com/p/Rheem-Performance-36-kw-Self-Mod...
/s
The worst part of the British system though (although I don’t think this has anything to do with voltage, IDK) is there is nowhere to plug-in your razor, hair clippers, hair dryer, toothbrush, curling iron, etc. etc.
There's a famous, common 20VA fixture by Legrand with a distinctive symbol. I asked an electrician about this last year. Most electricians will still fit them.
It won't supply a hairdryer or a pair of curling tongs, probably. Not that you really want such things in a bathroom or without an earth pin.
Generally I use an insulated 4L kettle that stays warm all day, so it heats up very quickly when needed and somewhat negates the issue.
For me, a big selling point of the kettle is that you don't have to clean it and stow it after every use, so I would still use the kettle even if it was slower (maybe no longer for pasta or when cooking in general though)...
edit: I guess you could just get a teapot that is induction-compatible, didn't think of that.
The difference is 2 minutes on the boil time of 1L.
> USA uses 230-240 VAC, too. The only difference is that we ground it in the center, creating "split" phases, reducing the peak voltage relative to ground and making it easier to interface low-power loads. But high-power loads (stoves, water heaters, clothes dryers, etc.) operate across the full voltage, reducing the current required.
3000 / 230 = 13.04
3000 / 240 = 12.5
We fit 13A fuses to the plugs of kettles. At 230V the tolerance would be too close.
Whereas in reality, a kettle designed to be 3kW at 240V would only be 2.755kW at 230V, or 2.520kW at 220V.
You'll often find the latter pair of number printed on the base of the kettle. i.e. 2520-3000W at 220-240V.
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Being compelled to wait two minutes more to boil a kettle for a cuppa would be enough to provoke an armed rebellion.
Not even sure I'm kidding.
https://en.wikipedia.org/wiki/Boiling_vessel
* https://www.youtube.com/watch?v=7yRGvMgieEU
Edison originally purchased others' dynamos, especially Wallace-Farmer, which was 110V (DC):
* https://americanhistory.si.edu/collections/search/object/nma...
* https://en.wikipedia.org/wiki/Moses_G._Farmer
So Edison's long-legged Mary-Ann was also 110V:
* https://www.collectorsweekly.com/stories/82967-thomas-edison...
* https://edison.rutgers.edu/life-of-edison/inventions?view=ar...
* https://americanhistory.si.edu/collections/search/object/nma...
Light bulbs in the early 1900s were first designed for lower voltages, and the grid slowly raised things over time, but at some point they couldn't go any higher because it would start blowing things, so they were 'stuck' in the 110-120V range.
50 Hz is about a G, and 60 Hz is about a B-flat. Video comparison: https://youtu.be/pMtn-loUrg8
https://www.youtube.com/watch?v=bWxS2njU-JI&t=355s
Are they, though? With modern appliances, power requirements are going up and 110V is struggling to keep up. One example would be an induction hob.
I know that technically US homes can access 230V but they aren't wired for that, probably 99% are wired just for 110V except for maybe a few special lines.
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(from the wiki: https://en.wikipedia.org/wiki/Electrical_wiring_in_the_Unite...)
So, the why is: More power, less copper, and that's really useful when you're resource constrained because someone has declared war on you and is blockading your coast, or you're recovering from that.Safety was one significant concern. 230-240V is more likely to stop a person's heart. 220 is available in most US homes for specific cases where it is more practical.
Speaking from experience, I don't think it is uncommon for a person to have been electrically shocked at some point in their lives --- often when they were a child.
https://electronics.stackexchange.com/questions/469913/compu...