this post was submitted on 16 Jun 2025
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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
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.
Wow, how do you do that?
Of course over-provisioning is a thing but that’s crazy. Maybe you have much smaller appliances or assume much lower usage, but 70a basically assumes 2 major appliances at a time, using close to max load, and with nothing else turned on.
Typical 240v major appliances
Of course you won’t use them all at once and they won’t usually be drawing their full rated load but I would not want to deal with being limited to one at a time so I can also turn on the lights or use the microwave
That can theoretically draw 280a, before you even count things like lights and small appliances. If you added up all possible circuits, you may be hitting 1000a theoretical in a modern house. I’m comfortable that My 200a service will handle any combination I might use, but 70a definitely not
By contrast I once lived in an apartment with 60a service. It did not have most of these large appliances but I frequently tripped the main with combinations like stove + window ac + microwave + lights
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))
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.
Let me clarify - those are standard sized circuits, not actual draw. However the service has to be sized to handle it, and over-provisioning to account for it.a customer might install a stove that draws the full load and might use all the burners at once, and you have to account for typical usage patterns.
For sure it’s a well earned stereotype that Americans use more electricity than many other places. We tend to have bigger houses, more and bigger appliances. We not only don’t have that base charge per size of service but too some extent are charged less to use more: essentially we subsidize people electric resistive heat, who can pay a lower usage rate. We also don’t usually have time of use metering, although some do: my rate is the same whether I charge my car at night or at peak time. And of course our current leadership is intent on rolling back the efficiency standards we have.
Taking your heat pump dryer example, those are finally available here but tend to cost a lot more than a traditional dryer: savings on efficiency will never make back the extra purchase cost More importantly they’ve only been available in small sizes, not typical for houses, especially with families