The "standard" car charger is usually overkill—but your electrician might not know that [32:26]
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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
- 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.
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.
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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
Aside from the heat pump we have all of these things and they’re often running all at once. Never had an outside
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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
- 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.
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.
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Did that account for battery lifetime, because if not, that could offset efficiency gains as fast charging degrades batteries.
I‘m not sure if fast charging degrades batteries. Just read somewhere an article stating that fast charging initially - first charge - boosts the overall capacity of the batterie due to chemical reactions that do not occur that long at anodes.
The issue with fast charging was the thermal management - it’s getting to hot. This is managed by good battery management and a different packaging of cells nowadays. I think fast charging isn’t an issue anymore. Can’t provide you a link or such, it’s what I gathered through serveral podcasts.
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I‘m not sure if fast charging degrades batteries. Just read somewhere an article stating that fast charging initially - first charge - boosts the overall capacity of the batterie due to chemical reactions that do not occur that long at anodes.
The issue with fast charging was the thermal management - it’s getting to hot. This is managed by good battery management and a different packaging of cells nowadays. I think fast charging isn’t an issue anymore. Can’t provide you a link or such, it’s what I gathered through serveral podcasts.
If you could find any evidence to support all that, i might consider it, until then, ill roll with what i know.
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If you could find any evidence to support all that, i might consider it, until then, ill roll with what i know.
Can you source your statement that fast charging reduces lifetime?
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Can you source that?
Here is a paper on the relationship between heat and battery degradation
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Aside from the heat pump we have all of these things and they’re often running all at once. Never had an outside
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+
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Not talking about the circuits, but the main electrical connection to the grid. To me it often seems like there's reluctance in
overcommittingoverprovisioning 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.
- Sometimes breakers don’t trip, so there’s a small risk of fire
- Restarting the whole house may have large initial loads as everything starts at once: more chance of it happening again or potentially damaging some appliances
- Risk of heat damage to wiring with repeated trips, risk of broken connections from more frequent expansion from heat/cool cycles
- Inconvenience, especially in the old days when you’d have to go through to set clocks. If while asleep you might not be awoken in time. If you weren’t home, maybe food gone bad
- Occasional home health appliances are critical to keep going
Realistically it comes down to how conservative you are with over-provisioning. You might also expect it to handle the load for 50 years of growing usage. In the US we have the expectation of rarely to never tripping the main and when that happens it’s more likely an electrician call
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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
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.
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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+
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)
- 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)
- Transfer costs, 0.0187 €/kWh during day, 0.0089 €/kWh during night
- Electricity tax, 0.0282752 €/kWh, includes national energy security taxes as well
- Cost of the actual electricity, typically ranges from -0.05 €/kWh to 0.20 €/kWh with yearly average being about 0.055 €/kWh
- Electricity company's margin for spot prices, 0.004 €/kWh
- 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.
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Also worth noting that breaker ratings are for instantaneous usage. A 15A 120v breaker can only actually support 12A of continuous usage. But it says 15, because most things use a little extra power when they first turn on. AC system spinning up the fans and compressor, for instance. Spinning things up takes more power than keeping it moving. If you put a 15A device on a 15A breaker, it would likely trip as soon as that device turned on. In that instance, you’d likely use a 20A breaker to support the 15A device instead. But that 20A breaker would also call for upgraded wiring and outlets which could support 20A.
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.
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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)
- 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)
- Transfer costs, 0.0187 €/kWh during day, 0.0089 €/kWh during night
- Electricity tax, 0.0282752 €/kWh, includes national energy security taxes as well
- Cost of the actual electricity, typically ranges from -0.05 €/kWh to 0.20 €/kWh with yearly average being about 0.055 €/kWh
- Electricity company's margin for spot prices, 0.004 €/kWh
- 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.
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.
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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.
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
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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.
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. -
ADHD guy here.
Wondering if these are reasons but need someone knowledgable to answer
- does the mains breaker have a limited amount of resets / duty cycle?
- is it bad for the whole house to trip sometimes? For me having to reset electronics, potential data loss etc makes it annoying.
- is there a potential for surging when the mains is flicked back on from everything starting simultaneously?
Tripping a breaker under fault conditions is somewhat destructive to the breaker, and if it keeps tripping, you'll notice it becomes easier and easier over time.
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