antimidas

Ok – that works a bit differently for our code then. Standard breakers are 10 A and 16 A, which means 10 A and 16 A constant load. Load characteristics affect which profile you use, typical residential alternatives are B and C profile breakers. B trips quicker, C trips slower and is meant for circuits with more reactive load characteristics. 16 A C profile breaker can take up to an hour to trip under 18-19 A load as an example. Your standard breaker can deal with quite a lot of inrush current – even with the faster B profile.

Wiring is built to withstand approximately 15 A when using a 10 A breaker, and 20 A when using a 16 A breaker. As such, the fuses display the value for constant loads, not for the peak. The most commonly used outlets in the EU (i.e. Schuko) are rated for 8 A continuous, 16 A peak, and are typically put on a 16 A circuit. 10 A circuits are mainly used for lighting nowadays, at least in Finland – 16 A being the standard for most things.

The voltage difference might have something to do with this, as 230 V will be capable of driving much more power though a potential short. As such any actual fault condition will most likely cause the fuse to trip quite quickly. Also current code mandates GFCI on all outlets in a house, which will help with smaller faults that aren't enough for the breaker to trip.

At least here the electrical service base rate is largely set by the max amperage you can draw from the grid. I'll use my own home's electricity cost breakdown as an example (all listed prices, even the additional tax, include our 25.5 % VAT)

1. Monthly base rate for your main breaker, depends on your grid operator – mine is 7.63€ for 3x25 A connection (among the cheapest grids in Finland, I previously used another example often seen in smaller cities, which is 29.71 €/month)
2. Transfer costs, 0.0187 €/kWh during day, 0.0089 €/kWh during night
3. Electricity tax, 0.0282752 €/kWh, includes national energy security taxes as well
4. Cost of the actual electricity, typically ranges from -0.05 €/kWh to 0.20 €/kWh with yearly average being about 0.055 €/kWh
5. Electricity company's margin for spot prices, 0.004 €/kWh
6. Electricity company's base rate, 4.90 €/Month

For many cities in Finland the base rate for grid connection is considerably higher, and especially for apartments tends to be the majority of your electricity bill outside major urban centers. Even in cities it makes up a large percentage, so there's a big incentive to not overspec your service.

As a European those power draws listed sound absolutely absurd to me. I mean, I can easily believe you, but a stove pulling 50 A at 240 V, so 12 kW, sounds like a complete overkill in normal use. The dryer power use also sounds comically high, when viewed from a country where heat pump dryers are the norm.

Let's go for a standard single family home example. Level 2 charger is either 8 A (5.5 kW) or 16 A (11 kW) three phase. On top of that, typical sauna is 6-7.5 kW, 1-2 heat pumps (approx. 1.5 kW a piece), stove (8.5 kW max), water heater (2-3 kW), + other appliances like dishwasher, washing machine etc.

It would seem like that easily trips the breaker, but you won't be charging the car and warming up the sauna at the same time, unless opting to 5.5 kW charging. However, you typically charge the car at night, when the other things running are the heat pumps and the water heater – this will end up drawing around 16 kW total (in the worst case scenario) which fits in the limit. When you don't count the car into the mix, there's plenty of power to go around.

There are multiple reasons behind this. One is our homes are relatively well insulated, which means that we can get by with a lot less AC and heating. Appliances in the EU are also generally more efficient – as an example, our dryers are typically based on heat pumps and pull a lot less amperage for the same performance. Lot of homes also don't have a dryer. Stoves have generally lower power requirements as well, and practically never draw peak power. Here's an example washer+dryer combo where the suggested fuse for the whole thing is 10 A (meaning 2.3 kW available for the combo).

So listing the same appliances you have (at 230 V single phase equivalent for simplicity, i.e. 75 A available (3 * 25))

• level 2 EV charger: 24-48 A depending on chosen speed
• stove: 20 A
• Heat pumps (also used for AC) worst case scenario approx. 15 A, practically only reached for longer periods in extreme cold
• dryer and washing machine: 10 A
• water heater: 16 A

Which will result in 79 A total worst case or 103 A depending on the car charger spec. A bit over the 75 A available, and not calculating additional smaller loads like the microwave, kettle, TV, lighting etc. That worst case will in practice never be reached, though, and even the main breaker typically has some tolerance before it trips (usually main breaker is using a slow-blow fuse equivalent profile, which doesn't immediately trip with a minor overload or a short spike). Our code mandates enough tolerance in wiring gauges that this doesn't pose any risk.

Why don't we want the added headroom then? Upgrading the service from 3x25A to 3x35A isn't really that expensive in urban areas, and can be done relatively simply? Well – Finns are stingy and depending on who happens to own your local distribution grid you can get heavily penalized monetarily in the long term, when upgrading the service to a higher tier. Caruna owns a lot of the Finnish distribution grid nowadays, and as an example from their pricing chart going from 3x25A to 3x35A raises your monthly base rate from 29.71 € to 51.68 €. That's 240 € extra per year, which is a pretty high cost for a just in case that's easily avoided. In cities that still have municipally owned distribution (Lahti, Turku, Helsinki as an example) the costs are typically much lower, both for upgrading the service and monthly costs, compared to the privately owned grids.

Also, it's typically not that expensive to upgrade your panel, if you live in a zoned area. Buildings in the unzoned area typically have good electrical connections since in the countryside you typically want access to three phases.

As an example for moving from older single phase service to 3x25A, it costs around 810 € typically, with 2000-3000 € as a worst case scenario. That's in Lahti, Finland – in Espoo it seems to be around 500 €

Of course there's then the need to upgrade the panel as well, but that's a relatively simple operation.

My childhood home had 3x90A breakers since it originally had a resistive heat setup, in a relatively large building (plus some other energy intensive equipment housed there). In reality it was far too much even then, the max load we calculated under full load was more like 25-30 kW.

Well, true. Fair enough

Ok, so the US-style GFCI-breakers are indeed a lot more expensive than similarly rated DIN-rail alternatives. TIL

one of us

1. Hadn't considered that one TBH, no practical limits with actuations (rated in the thousands) but they're probably not rated for that many trips under a fault condition – now I'm curious, will have to dig up a spec sheet at some point
2. Not really, unless you have equipment that's poorly designed everything should be fine. It's not much different from a brownout, and things should be configured to deal with that anyways if you don't have a UPS
3. If there are a lot of reactive loads, then yes – e.g. electric motors, large capacitors. Those will have a large inrush when started again. Typically there isn't that much reactive loading in a residential home though, and it should be covered by the latency designed into the breaker.

The first point is actually a really good one, and one I didn't really remember to consider. I'd guess it has at least something to do with that (and would explain why many homes around here are still configured with traditional fuses for the main connection – no need to worry about lifetime when you have to replace them anyways)

Not talking about the circuits, but the main electrical connection to the grid. To me it often seems like there's reluctance in ~~overcommitting~~ overprovisioning that capacity: as an example, four 16A circuits on a 25A main breaker. Here that's quite common, but even in Tech connections videos I've seen him bring up smart electric cabinets or automatic load monitoring when putting enough capacity on the mains to possibly go over.

What I'm asking is, why bother? If you trip the mains by having too much load, just reset the breaker and be done with it. No need to automate things to not run into that situation, one will learn to not have the oven on while charging the car full blast. No need to gimp the charger amperage since you're running a new circuit anyway, and it's not like it's much different running a 20A circuit vs a 40A one. If that's 70% of your total available capacity, it doesn't matter – worst you have to do is walk downstairs and flip a switch.

I might've been unclear, I don't mean 230 V by itself, but three-phase distribution. The standard socket is labeled either 3x16A 230V alternatively labeled 380V 16A. Typically uses an IEC 60309 plug that looks like this:

(Source: https://www.plugsocketmuseum.nl/IEC60309_2.html)

Three phase has other benefits besides just more power, the US has it with their lower voltage as well, but typically reserved just for larger buildings.

Are they somehow more expensive in the US? 40A 230V rated ones cost something like 30-50 € around here which doesn't feel that expensive to me. I'll admit it's considerably more expensive (~4x the price) than a standard breaker, but it's still more like a rounding error in overall costs.

Although EVSE's projection doesn't require you to periodically trip the GFCI so it doesn't get stuck, which is a major plus.

One thing I really don't get in the discussion around EVs and charging is, why are people so afraid of tripping the main breaker? If you have a total of e.g. 17 kW available and happen to go over, just reset the main breaker (or replace it in case it's still a traditional one). It's there precisely so that you wouldn't need to care about overloading the connection.

In my experience people get by with a 3x25A (17 kW available, matches approximately a 70A service in the US) while using the available power to

• heat/cool a single family home (in -20 °C weather mind you)
• run all appliances (including the oven, stove, dryer etc.)
• heat up a sauna
• charge an EV
• whatever else you typically would want to plug in, kettles and such

While it's true you can trip the main breaker if you have everything on at the same time, typically it never happens even if there are no lockouts in place preventing overuse. And it's not like tripping it causes any permanent harm.

Why is an electrical service upgrade constantly brought up as a solution when any home with >15 kW of available power won't need it? Is it against code to purposefully overcommit your mains in the US or something?

Edit: there were valid concerns raised over how long-lived the breakers are (probably won't be rated for tens of fault-condition related trips), also that these smaller service specs aren't as common as I've gathered from the media. That might have something to do with this at least. Thanks for the replies – it's been an interesting discussion.

Yep – US also doesn't generally do residential three-phase unlike many countries in the EU. A lot of garages around here have 3x16A 230V, not (only) due to the power requirements but because having three phases allows for simplest induction motors for things like blowers and circular saws. When you have three phases having a proper outlet in the garage starts making sense.

Around here (Finland more specifically) we have three-phase even in most apartments. My two bedroom apartment has a 3x25A main breaker, and two devices on 3x16A circuit's – the sauna stove and oven+stovetop. Most single-family homes have 3x25A or 3x36A as well.

US households are missing out on a lot of things due to their split-phase system.