5 ms·

Unique British problem caused by tea. What must you Americans think of us? (is it true that Americans don't have enough power through the mains to boil a kettle

Unique British problem caused by tea. What must you Americans think of us? (is it true that Americans don't have enough power through the mains to boil a kettle?)

jdminhbg 14y ago
That's not true, although it does take a little longer here than in the UK. Mainly, we just prefer coffee.
- jvehent 14y ago
  And pop-corn machines...
deleted 14y ago
[deleted]
scaphandre 14y ago
Is that tongue-in-cheek? Of course they can boil a kettle. It does take ages, though. Conventional kettles seemed to take perhaps twice as long to boil in CA than in UK. Boiling water at 230V,13A in the UK is going to be much faster than 120V,15A in the US.
- wglb 14y ago
  Um, no. Heating rate is a function of wattage, not voltage. EDIT: my error. I neglected to notice the amps shown and just picked up on the voltage.
  - tacticus 14y ago
    W = V * I W1 = 230V * 13A = 2990 W2 = 120V * 15A = 1800 slight bit more power in the 220-240v at 10-13ish amp system than 120 @ 15
    - jsight 14y ago
      Don't most stoves in the US use 220? EDIT: oops, just realized that these are likely electric kettles. I was thinking of the stovetop variety.
      - tacticus 14y ago
        Yep these are separate plugin versions. the kettle i just bought on the weekend draws 2300W
  - function_seven 14y ago
    I think he was implying power by listing the voltages and currents (230/13 vs. 120/15)
- csense 14y ago
  Assuming you're heating 300 mL of water. The specific heat capacity of water is 4.2 J / (g°C) [3]. If you're heating it from 20°C room temperature to 100°C boiling, that's a temperature increase of 80°C. The metric system is set up so that 1 mL of water weighs 1 g (give or take a little based on temperature, pressure, impurities, etc), i.e. the density of water is 1g / mL. Plugging in the numbers: (4.2 J/(g°C)) * (1 g/mL) * 300 mL * 80°C = 100800 J So approximately 100 kJ of energy is needed to boil 300 mL of water. One kW of power is a delivery of one kJ per second. How much power do we have available? In the UK, there's 230V * 13A = 2990 W ~ 3 kW. In the US, there's 120V * 15A = 1800 W = 1.8 kW. So in the UK it takes 100 kJ / 3 kW ~ 33 seconds. (One kW is 1 kJ / s.) In the US it takes 100 kJ / 1.8 kW ~ 56 seconds. These times are likely lower bounds. Assuming the voltage and current given by the parent are correct (or you measure them directly and substitute those numbers) and you measure out exactly 300 mL of distilled water, the biggest source of error is probably the fact that you're heating more than the water. You also have to heat the resistor in your kettle or electric stove, the thermally conducting, electrically insulating housing for the resistor, the kettle itself, and the surrounding air. And water molecules heat unevenly (my thermodynamics is a bit sketchy but I think this is called a Boltzmann distribution [2]?) so a few will evaporate before the water reaches a uniform 100°C, carrying off energy. My guess would be that the above effects matter less in the UK because the higher power means they would have less time to operate. I'm pretty sure that this analysis deals correctly with the fact that the current is AC [1]; if any experts on the mysteries of power engineering want to correct me, please do reply. [1] http://en.wikipedia.org/wiki/Root_mean_square#Average_electrical_power http://en.wikipedia.org/wiki/Root_mean_square#Average_electr... [2] http://en.wikipedia.org/wiki/Boltzmann_distribution http://en.wikipedia.org/wiki/Boltzmann_distribution [3] http://en.wikipedia.org/wiki/Density_of_water#Heat_capacity_and_heats_of_vaporization_and_fusion http://en.wikipedia.org/wiki/Density_of_water#Heat_capacity_...
acomjean 14y ago
In the US in the places I've lived, Ive uses and continue to use municipal gas to cook, and boil water for tea. It heats up water fast. Doesn't strain the electric grid but has other issues.
- finnw 14y ago
  Does gas not have exactly the same issue? i.e. mains pressure drops when many people in the area are using it at the same time?
  - ars 14y ago
    You can store gas, you can't store electricity. So it's very easy to buffer gas for things like this.
danellis 14y ago
American power does seem a bit lacking. Turning on the hoover makes the lights dim.
- sbierwagen 14y ago
  Branch circuit voltage sag, from running the vacuum on the same circuit as the room lighting. Doesn't happen in commercial buildings, where the lighting runs on 277v.
deleted 14y ago
[deleted]
rmc 14y ago
(is it true that Americans don't have enough power through the mains to boil a kettle?) Wait till you find out that they don't really use kettles. They put an old fashioned pot/kettle on the oven hob....
- Thrymr 14y ago
  Though mostly we just go out to Starbucks.

Unique British problem caused by tea. What must you Americans think of us? (is it true that Americans don't have enough power through the mains to boil a kettle?)

jdminhbg 14y ago

That's not true, although it does take a little longer here than in the UK. Mainly, we just prefer coffee.

jvehent 14y ago
And pop-corn machines...

deleted 14y ago

[deleted]

scaphandre 14y ago

Is that tongue-in-cheek? Of course they can boil a kettle. It does take ages, though. Conventional kettles seemed to take perhaps twice as long to boil in CA than in UK. Boiling water at 230V,13A in the UK is going to be much faster than 120V,15A in the US.

wglb 14y ago
Um, no. Heating rate is a function of wattage, not voltage. EDIT: my error. I neglected to notice the amps shown and just picked up on the voltage.
- tacticus 14y ago
  W = V * I W1 = 230V * 13A = 2990 W2 = 120V * 15A = 1800 slight bit more power in the 220-240v at 10-13ish amp system than 120 @ 15
  - jsight 14y ago
    Don't most stoves in the US use 220? EDIT: oops, just realized that these are likely electric kettles. I was thinking of the stovetop variety.
    - tacticus 14y ago
      Yep these are separate plugin versions. the kettle i just bought on the weekend draws 2300W
- function_seven 14y ago
  I think he was implying power by listing the voltages and currents (230/13 vs. 120/15)
csense 14y ago
Assuming you're heating 300 mL of water. The specific heat capacity of water is 4.2 J / (g°C) [3]. If you're heating it from 20°C room temperature to 100°C boiling, that's a temperature increase of 80°C. The metric system is set up so that 1 mL of water weighs 1 g (give or take a little based on temperature, pressure, impurities, etc), i.e. the density of water is 1g / mL. Plugging in the numbers: (4.2 J/(g°C)) * (1 g/mL) * 300 mL * 80°C = 100800 J So approximately 100 kJ of energy is needed to boil 300 mL of water. One kW of power is a delivery of one kJ per second. How much power do we have available? In the UK, there's 230V * 13A = 2990 W ~ 3 kW. In the US, there's 120V * 15A = 1800 W = 1.8 kW. So in the UK it takes 100 kJ / 3 kW ~ 33 seconds. (One kW is 1 kJ / s.) In the US it takes 100 kJ / 1.8 kW ~ 56 seconds. These times are likely lower bounds. Assuming the voltage and current given by the parent are correct (or you measure them directly and substitute those numbers) and you measure out exactly 300 mL of distilled water, the biggest source of error is probably the fact that you're heating more than the water. You also have to heat the resistor in your kettle or electric stove, the thermally conducting, electrically insulating housing for the resistor, the kettle itself, and the surrounding air. And water molecules heat unevenly (my thermodynamics is a bit sketchy but I think this is called a Boltzmann distribution [2]?) so a few will evaporate before the water reaches a uniform 100°C, carrying off energy. My guess would be that the above effects matter less in the UK because the higher power means they would have less time to operate. I'm pretty sure that this analysis deals correctly with the fact that the current is AC [1]; if any experts on the mysteries of power engineering want to correct me, please do reply. [1] http://en.wikipedia.org/wiki/Root_mean_square#Average_electrical_power http://en.wikipedia.org/wiki/Root_mean_square#Average_electr... [2] http://en.wikipedia.org/wiki/Boltzmann_distribution http://en.wikipedia.org/wiki/Boltzmann_distribution [3] http://en.wikipedia.org/wiki/Density_of_water#Heat_capacity_and_heats_of_vaporization_and_fusion http://en.wikipedia.org/wiki/Density_of_water#Heat_capacity_...

acomjean 14y ago

In the US in the places I've lived, Ive uses and continue to use municipal gas to cook, and boil water for tea. It heats up water fast. Doesn't strain the electric grid but has other issues.

finnw 14y ago
Does gas not have exactly the same issue? i.e. mains pressure drops when many people in the area are using it at the same time?
- ars 14y ago
  You can store gas, you can't store electricity. So it's very easy to buffer gas for things like this.

danellis 14y ago

American power does seem a bit lacking. Turning on the hoover makes the lights dim.

sbierwagen 14y ago
Branch circuit voltage sag, from running the vacuum on the same circuit as the room lighting. Doesn't happen in commercial buildings, where the lighting runs on 277v.

deleted 14y ago

[deleted]

rmc 14y ago

(is it true that Americans don't have enough power through the mains to boil a kettle?) Wait till you find out that they don't really use kettles. They put an old fashioned pot/kettle on the oven hob....

Thrymr 14y ago
Though mostly we just go out to Starbucks.