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submitted 2 days ago by [email protected] to c/[email protected]
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[-] [email protected] 10 points 1 day ago* (last edited 1 day ago)

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.

[-] [email protected] 5 points 1 day ago

why are people so afraid of tripping the main breaker?

Not everyone know as much as electricity as you, I think is natural to be afraid of something you not know so much and that potentially can burn your house.

[-] [email protected] 3 points 1 day ago* (last edited 1 day ago)

Where I live, there is a pole fuse, which is, as the name implies, on the pole, and only a linesman can change it.

Massive pain in the ass if that pops.

[-] [email protected] 3 points 21 hours ago

Yes… I have experience here. I’m using dynamic energy tariffs so during real sunny weekends the price can be negative - I get paid to consume power. As you’d might imagine, I charged the EV, disconnected my solar panels, turned on all HVAC to max cooling and set both my ovens to clean-mode…….. Put some clothes in the dryer, tripped my fuse and cost me €140,- to replace it. Also, power for that phase went out which contained one of the ovens, which was midcycle. Couldn’t cool itself down, melted the plastics 😬. But at least I gained €4 during the timeframe it worked.

[-] [email protected] 8 points 1 day ago* (last edited 1 day ago)

The way that it works in most countries is that the breakers are per circuit in your wall. The breakers trip in order to prevent that single circuit from overheating and starting a fire in your walls.

Let’s say you have a wire that’s rated for 16amps. More than that and it becomes a fire risk just threw overheating. @230v that gives you 3680w per circuit.

If you have your industrial microwave, water heater, and car charger all going at the same time on that same circuit. This will draw way more than 3680w and thus would go over that 16a limit.

The breakers trips once you go over that 16a limit for safety. It’s a good thing. This all being said no sane electrician would put those three things on the same circuit. lol.

Circuit breakers are actually what enable you to safely over provision. Without them fires would just be a matter of time.

I know it works this way in the U.S. and Germany at least.

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[-] [email protected] 2 points 1 day ago* (last edited 1 day ago)

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

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

  • level 2 EV charger: 50a
  • stove: 50a
  • central ac: 40a
  • dryer: 40a
  • heat pump: 50a+
  • water heater: 50a

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

[-] [email protected] 3 points 1 day ago* (last edited 1 day ago)

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.

[-] [email protected] 2 points 22 hours ago

As a European those power draws listed sound absolutely absurd to me

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

[-] [email protected] 2 points 1 day ago

Aside from the heat pump we have all of these things and they’re often running all at once. Never had an outside

[-] [email protected] 1 points 1 day ago* (last edited 1 day ago)

There’s a standard

Then you’d round up to the nearest service level. Realistically, I believe most recent-ish houses are 200a service now with larger ones or hot climates tending to 300a+

[-] [email protected] 2 points 1 day ago* (last edited 1 day ago)

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.

[-] [email protected] 1 points 22 hours ago

That may be the entire difference, we don’t have that base cost. Our monthly bill is mainly the actual useage, itemized into generating cost, transfer cost, fees and taxes. There is usually an administrative fee but that’s fixed cost.

[-] [email protected] 75 points 2 days ago

Highly recommend Technology Connections for anyone interested in easy to understand, relatable breakdown videos of technology.

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[-] [email protected] 51 points 2 days ago

I think “might be overkill” would be a better title and position than “usually overkill.”

There is absolutely a subset of EV drivers that could get by with a level 1 charger (ignoring time of day rates), but most people would fall behind anytime they drive further than the average number of miles. Sure, taking 10 hours to recharge your Chevy Bolt overnight when you’ve driven 40 miles is doable; 64 hours when you’ve returned home from a longer trip isn’t.

I own a PHEV, and installing a level 2 charge has been one of the best quality of life and financial changes.

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[-] [email protected] 26 points 2 days ago

You might not need 50 amps now. But that line is a 1 time cost and maybe you'll want to weld one day.

[-] [email protected] 7 points 1 day ago

My wife had to try charging on a 120V outlet last winter. The plug couldn't even keep up with the battery heating requirements to actually start charging; the battery percentage was going DOWN while plugged in. It was -25°C outside though, so it's a specific situation, but it's actually why she had to try to charge; it's a trip we can easily do without charging in the summer.

[-] [email protected] 3 points 1 day ago* (last edited 1 day ago)

Car specific maybe? I was able to charge at -30C outside from a 120V outlet last winter.

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[-] [email protected] 25 points 2 days ago* (last edited 2 days ago)

I agree with this youtube comment:

As an electrician (in Australia), I agree with your basic premise. However, if you are asking me to install an EV charger, unless you tell me “I want it to charge slowly with a limited current capacity”, I am going to assume it is to charge an EV under ALL situations - fast to slow, for whoever may drive one today or in the future, even with a potential new homeowner. We generally do our work with the priority order (1) safety - nobody gets an electric shock and nothing catches fire; (2) avoidance of nuisance i.e. the thing you just installed doesn’t work and keeps tripping the breaker 😑 (3) avoiding needing replacement electrical work for at least 25 - 50 years

Also I live in a townhouse with no garage. Our charger is between the neighborhood sidewalk and our parking spaces, so I'd prefer keeping it plugged in as little as possible to minimize any issues with foot traffic (neighbors, delivery people, garbage pickup, etc). I've seen other townhouse EV owners literally run an extension cable over the sidewalk to do an L1 charge for their EV and that's just asking for trouble.

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[-] [email protected] 30 points 2 days ago

could this be an article instead of a video? I'm not spending 32 minutes watching this, tbh

[-] [email protected] 41 points 2 days ago

This has to be my favorite thing about Jeff Geerling vs other YouTube channels, he'll make an accompanying blog post to go with each of his main channel videos that is effectively an annotated text version of the video with appropriately embedded images and links.

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[-] [email protected] 30 points 2 days ago

You should give it a shot. The dudes videos are super captivating.

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[-] [email protected] 6 points 1 day ago

I watched the video and it seems to make good points, but no matter how many times I see something related to US power circuits it just feels so ... antique? I have 3x25A fuses on the house and several 3x16A outlets around so getting 11kW out is just a matter of plugging in a socket.

Obviously it would be a good thing to have controls so that water heater, floor heating or sauna stove aren't all on together but I think I've replaced a single 25A fuse over 10 years we've lived on this house and I'm pretty sure that was caused by a small(ish) surge on the grid and not our load.

[-] [email protected] 8 points 1 day ago

I'm not sure what you mean by this. Any modern US house would have a similar capability, it's just older homes that would struggle since there would never be a need for such high power devices in a garage.

Most older garages would only need enough power to run a single lightbulb, if it was slightly newer, maybe a low power automatic garage door opener.

It's the same in any country with buildings over 100 years old.

[-] [email protected] 4 points 1 day ago

It’s the same in any country with buildings over 100 years old.

In here 100+ year old houses are pretty common but practically all of them still have at least somewhat up to date electrics with that 3-phase input. It's been around for decades after all. My house is built originally 1928 and my mothers house is from 1909 and both of them have 3x25A main breakers with those 380V 16A CEE sockets around.

And as garages commonly double as a work space with 3-phase induction motors on the tools it's still pretty common to have that 3x16A available as it's not that much more expensive to pull 5x2.5mm² cable to the garage compared to 3x2.5mm² for single phase 16A outlet.

[-] [email protected] 3 points 1 day ago* (last edited 1 day ago)

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.

[-] [email protected] 4 points 1 day ago

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.

[-] [email protected] 3 points 1 day ago

having three phases allows for simplest induction motors for things like blowers and circular saws

Which is really nice. No capacitors or other electronics needed. My old drill press has 750W 3-phase motor and it just works. Also having the power available gives options like running a 7kW log splitter with circular saw at the end of 20 meter long extension cord.

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this post was submitted on 16 Jun 2025
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