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.
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.
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.
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
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.
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
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
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)
I don’t think overprovisioning is a thing that is realistically is a problem in the U.S. or in Germany. I know that modern homes tend to have 300amp mains. Older homes 100amps. You would have to have a house that was wired in 1920 in order to have a 20amp mains available. In that case you have bigger issues safety wise.
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.
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.
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.
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
The infinitely easier solution is to let the car charger know how much power is available to draw.
Well, true. Fair enough
ADHD guy here.
Wondering if these are reasons but need someone knowledgable to answer
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.
one of us
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)
I don’t think overprovisioning is a thing that is realistically is a problem in the U.S. or in Germany. I know that modern homes tend to have 300amp mains. Older homes 100amps. You would have to have a house that was wired in 1920 in order to have a 20amp mains available. In that case you have bigger issues safety wise.