this post was submitted on 16 Jun 2025
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26
The "standard" car charger is usually overkill—but your electrician might not know that [32:26] (www.youtube.com)
submitted 1 week ago by [email protected] to c/[email protected]
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[–] [email protected] 0 points 1 week ago* (last edited 1 week ago) (2 children)

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.

[–] [email protected] 2 points 1 week ago* (last edited 1 week ago)
  1. Sometimes breakers don’t trip, so there’s a small risk of fire
  2. 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
  3. Risk of heat damage to wiring with repeated trips, risk of broken connections from more frequent expansion from heat/cool cycles
  4. 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
  5. 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

[–] [email protected] 0 points 1 week ago* (last edited 1 week ago) (2 children)

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?
[–] [email protected] 2 points 1 week ago

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.

[–] [email protected] 1 points 1 week ago

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)