3 ms·

In many countries charging a car in a wallplug is a fire hazard (they are not rated for the heat).

by msh 1y ago

throwaway-blaze 1y ago
This doesn't make sense. Wall plugs (like circuit breakers) are designed for a particular max amperage draw. If I have a 10A 120V circuit and wall plug, I can't charge my car at 8A? I have wall ovens that connect via a 50A circuit. Do I need to worry about fire hazards when I bake something for hours and hours?
- Volundr 1y ago
  Not an electrician, consult a real one for any actual electrical work or questions. It's complicated. Heat builds up over time. So for example your standard 15 amp breaker on a 14 gauge wire in the US is rated for 15 amps of intermittent use, but if you draw that continuously without letting the heat dissipate it becomes a fire hazard. IIRC circuits are generally rated for ~80% of their max load for continuous use, so that 15 amp circuit is considered good for 12 continuous. Or in your 10 amp example 8 should be ok. Your oven and circuit should be sized such that your long cooks aren't a concern, if you look at it's label you'll probably find it has a max draw of well below 50amps, but if you have actual doubts ask a professional.
  - Astronaut3315 1y ago
    Also not an electrician. A concern for high current outlets in the US, such as NEMA 14-50, is that they weren't necessarily designed for a large number of plug/unplug cycles. Typically you'd plug your stove in and leave it there for years to decades. If you use the same 14-50 outlet for car charging, which is not uncommon, the contacts can lose their grip over time. End users may want to take their mobile EVSE with them and incur cycles on the outlet. Properly installed but worn 14-50s have been known to melt or even catch fire under these conditions. End users should prefer to have their EVSE(s) hardwired or installed with a higher grade outlet like Hubbell or Bryant.
  - hvb2 1y ago
    Having charged 2 EVs on wall sockets for years, I've not seen them go over 12 amps, so that checks out. One of those was a leaf
  - eldaisfish 1y ago
    i'm always surprised how people here downvote correct information. This is 100% correct because heat in electrical wiring is a function of power (current) and time. The vast majority of electrical devices in a typical home use under 80% of their rated power. The few that do use their full power, like a resistive heater, often do not run continuously. In contrast, it is completely normal to charge an EV at a socket's maximum power for over ten hours straight. This time component is why charging EVs from a regular AC outlet can be a fire risk.
- msh 1y ago
  https://aminacharging.com/articles/can-i-charge-my-car-in-a-socket/#:~:text=With%20that%20much%20power%2C%20there's,has%20left%20the%20socket%20either. https://aminacharging.com/articles/can-i-charge-my-car-in-a-...
  - Miraste 1y ago
    That still didn't explain anything. Surely the car could limit itself to 80% of standard socket rated output for continuous draw, like they do in other countries. Are Norwegian outlets commonly installed so far below spec that that will cause them to catch fire? What was the impetus for this regulation?
    - msh 1y ago
      I don’t know exactly for Norway as that was the best English article I could find. A standard danish outlet (they are crap) is 16A but is not rated for more than 6A if the load is continuous for more than 2 hours.
      - aidenn0 1y ago
        Then use a 6A charger? Assuming it's 2x the voltage of the US that's the same power as a 12A charger would be in the US, and I get plenty of charging at 16A (which is the maximum continuous load on a 20A circuit)
- quesera 1y ago
  FWIW, oven/range circuits are notoriously overspecified. Code in the US is 220V/50A. Your wall oven will get the same, despite having a much lower max draw than the usual oven/cooktop combination. 50A (upgraded from 30A several years ago) is specified for having the oven plus all cooktop elements ON. Maximum instantaneous draw will be below 50A. There's also the standard 20% headroom allotment, and some additional safety margin to account for the heat generated by all of the above being ON (or high duty cycle) for an extended period.
barbazoo 1y ago
Source?
- msh 1y ago
  https://aminacharging.com/articles/can-i-charge-my-car-in-a-socket/#:~:text=With%20that%20much%20power%2C%20there's,has%20left%20the%20socket%20either. https://aminacharging.com/articles/can-i-charge-my-car-in-a-...
  - barbazoo 1y ago
    > And since your car needs so much power stored in its battery to drive, it will probably pull more power than any other electrical appliance in your home. Probably? No, it pulls less than my dryer which runs at 240V15A I think but also just the same as my 1500W space heater. You can totally control how much power the charger should draw. > With that much power, there’s a risk of overheating and fire. Unlike a dedicated EV charger, a socket is simply not equipped to handle the amount of electricity needed to charge a car battery. Wrong assumption leads to wrong conclusion. Any charger you can physically plug in will work in a house that's wired up to standard.
    - msh 1y ago
      Your dryer will load the socket for far less time than a car charger and will probably not use 15A for the entire drying cycle. It’s the long charge time that leads to heat buildup, not the max amp. Where I am from standard outlets can deliver 16A but are not rated for more than 6A if the load is longer than 2 hours.
      - barbazoo 1y ago
        Here it's 15A and the charger itself actually tops out at 12A as is common. Perhaps that being common is how to avoid fires. I'm actually not sure now if that's a law or just best practice here.
- schmookeeg 1y ago

In many countries charging a car in a wallplug is a fire hazard (they are not rated for the heat).

by msh 1y ago

In many countries charging a car in a wallplug is a fire hazard (they are not rated for the heat).

This doesn't make sense. Wall plugs (like circuit breakers) are designed for a particular max amperage draw. If I have a 10A 120V circuit and wall plug, I can't charge my car at 8A? I have wall ovens that connect via a 50A circuit. Do I need to worry about fire hazards when I bake something for hours and hours?

Volundr 1y ago
Not an electrician, consult a real one for any actual electrical work or questions. It's complicated. Heat builds up over time. So for example your standard 15 amp breaker on a 14 gauge wire in the US is rated for 15 amps of intermittent use, but if you draw that continuously without letting the heat dissipate it becomes a fire hazard. IIRC circuits are generally rated for ~80% of their max load for continuous use, so that 15 amp circuit is considered good for 12 continuous. Or in your 10 amp example 8 should be ok. Your oven and circuit should be sized such that your long cooks aren't a concern, if you look at it's label you'll probably find it has a max draw of well below 50amps, but if you have actual doubts ask a professional.
- Astronaut3315 1y ago
  Also not an electrician. A concern for high current outlets in the US, such as NEMA 14-50, is that they weren't necessarily designed for a large number of plug/unplug cycles. Typically you'd plug your stove in and leave it there for years to decades. If you use the same 14-50 outlet for car charging, which is not uncommon, the contacts can lose their grip over time. End users may want to take their mobile EVSE with them and incur cycles on the outlet. Properly installed but worn 14-50s have been known to melt or even catch fire under these conditions. End users should prefer to have their EVSE(s) hardwired or installed with a higher grade outlet like Hubbell or Bryant.
- hvb2 1y ago
  Having charged 2 EVs on wall sockets for years, I've not seen them go over 12 amps, so that checks out. One of those was a leaf
- eldaisfish 1y ago
  i'm always surprised how people here downvote correct information. This is 100% correct because heat in electrical wiring is a function of power (current) and time. The vast majority of electrical devices in a typical home use under 80% of their rated power. The few that do use their full power, like a resistive heater, often do not run continuously. In contrast, it is completely normal to charge an EV at a socket's maximum power for over ten hours straight. This time component is why charging EVs from a regular AC outlet can be a fire risk.
msh 1y ago
https://aminacharging.com/articles/can-i-charge-my-car-in-a-socket/#:~:text=With%20that%20much%20power%2C%20there's,has%20left%20the%20socket%20either. https://aminacharging.com/articles/can-i-charge-my-car-in-a-...
- Miraste 1y ago
  That still didn't explain anything. Surely the car could limit itself to 80% of standard socket rated output for continuous draw, like they do in other countries. Are Norwegian outlets commonly installed so far below spec that that will cause them to catch fire? What was the impetus for this regulation?
  - msh 1y ago
    I don’t know exactly for Norway as that was the best English article I could find. A standard danish outlet (they are crap) is 16A but is not rated for more than 6A if the load is continuous for more than 2 hours.
    - aidenn0 1y ago
      Then use a 6A charger? Assuming it's 2x the voltage of the US that's the same power as a 12A charger would be in the US, and I get plenty of charging at 16A (which is the maximum continuous load on a 20A circuit)
quesera 1y ago
FWIW, oven/range circuits are notoriously overspecified. Code in the US is 220V/50A. Your wall oven will get the same, despite having a much lower max draw than the usual oven/cooktop combination. 50A (upgraded from 30A several years ago) is specified for having the oven plus all cooktop elements ON. Maximum instantaneous draw will be below 50A. There's also the standard 20% headroom allotment, and some additional safety margin to account for the heat generated by all of the above being ON (or high duty cycle) for an extended period.

barbazoo 1y ago

Source?

msh 1y ago
https://aminacharging.com/articles/can-i-charge-my-car-in-a-socket/#:~:text=With%20that%20much%20power%2C%20there's,has%20left%20the%20socket%20either. https://aminacharging.com/articles/can-i-charge-my-car-in-a-...
- barbazoo 1y ago
  > And since your car needs so much power stored in its battery to drive, it will probably pull more power than any other electrical appliance in your home. Probably? No, it pulls less than my dryer which runs at 240V15A I think but also just the same as my 1500W space heater. You can totally control how much power the charger should draw. > With that much power, there’s a risk of overheating and fire. Unlike a dedicated EV charger, a socket is simply not equipped to handle the amount of electricity needed to charge a car battery. Wrong assumption leads to wrong conclusion. Any charger you can physically plug in will work in a house that's wired up to standard.
  - msh 1y ago
    Your dryer will load the socket for far less time than a car charger and will probably not use 15A for the entire drying cycle. It’s the long charge time that leads to heat buildup, not the max amp. Where I am from standard outlets can deliver 16A but are not rated for more than 6A if the load is longer than 2 hours.
    - barbazoo 1y ago
      Here it's 15A and the charger itself actually tops out at 12A as is common. Perhaps that being common is how to avoid fires. I'm actually not sure now if that's a law or just best practice here.
schmookeeg 1y ago