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This is an observation I am basing very much basing on anecdotal evidence. I have recently moved to the U.S from Europe, and have previously lived in New Zealand. I find that kettles (known as tea kettles here) take a lot longer to boil water in the United States.

Someone suggested to me that this is due to the lower mains voltage level (120 as opposed to 240V in NZ). Is this correct? I would have thought it would be easy to compensate for by increasing the current.

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  • \$\begingroup\$ There is also a significant influence of air pressure or height. The closer to sea level you are, the higher the boiling temp, and the slower the cooking in a boiler with the same rating. \$\endgroup\$ – posipiet Jan 11 '13 at 7:39
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    \$\begingroup\$ While this question, as phrased, it not really suited for EE.sx, the differences that lead to the OP asking the question (e.g. the difference in available power from an outlet in various countries) does seem appropriate for the EE.sx site. As such, I think it might need rephrasing, but it seems useful to keep around. \$\endgroup\$ – Connor Wolf Jan 11 '13 at 8:36
  • \$\begingroup\$ This is very much a real question which highlights the impact of electrical design decisions, in this case domestic outlet voltage. Electric kettles as discussed here may not be so common in the US (Boston tea party fallout making a countertop coffee maker more patriotic) but are well known and depended upon in much of the developed world. (Or at least the 240 vac regions). \$\endgroup\$ – Chris Stratton Jan 11 '13 at 15:00
  • \$\begingroup\$ @ChrisStratton This seems off-topic to me as a clear impact in consumer-electronics support. There is no design here, just discussion of what leads to a kettle boiling slower in one country then another. We would need detailed measurements on the kettle, if it is a case that it is the exact same kettle with a cable to the outlet I think the answer is relatively easy to explain, lower voltage-same resistance. While I agree this highlights impacts of electrical design decisions, do do many Super User questions discussing hardware choices, that does not make the question fit automatically. \$\endgroup\$ – Kortuk Jan 11 '13 at 19:48
  • \$\begingroup\$ If this question were on topic we would have to have detailed info on altitude, which kettles were used and full electrical specs on how they were implemented. \$\endgroup\$ – Kortuk Jan 11 '13 at 19:50
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It's not just you, and you are in fact correct.

What it boils down to is the available power on the local circuit breaker.

In the US, a house is normally broken up into various segments, each getting it's power through a 15A circuit breaker.

As such, the maximum available power for the circuit is 120V * 15A, or 1800 watts.
Furthermore, to prevent the breaker from tripping if a lamp or other device is also plugged into a circuit, the maximum power I have seen a single device draw is generally limited to ~1500W.

In a country with 240V mains, you only need to draw ~6.25A to get an equivalent 1500W.
A quick search for 240V electric kettles leads me to some devices that claim *3100 watt heaters.

I don't know what the standard/common breaker rating is in a 240V country, but if it's also 15A, that would mean that you can draw approximately twice the amount of power from any one outlet then you can in a 120V country.

That likely explains the difference you perceive.


Edit:

From @RJR in the comments:

Common breakers in Europe (NL at least) are 16A. 10A (older homes, lights) and 20A (power appliances like hotplates/hobs) are used also but not generally for normal power outlets.

As such, the maximum available power for a electric kettle is indeed twice the maximum available power in most 120V houses.

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    \$\begingroup\$ Common breakers in Europe (NL at least) are 16A. 10A (older homes, lights) and 20A (power appliances like hotplates/hobs) are used also but not generally for normal power outlets. \$\endgroup\$ – RJR Jan 11 '13 at 8:28
  • \$\begingroup\$ @RJR - Excellent! That nails it, then. \$\endgroup\$ – Connor Wolf Jan 11 '13 at 8:33
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    \$\begingroup\$ "What it boils down to" - heh :) \$\endgroup\$ – Martin Thompson Jan 11 '13 at 9:58
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    \$\begingroup\$ In the UK at least every mains plug is fitted with a <=13A fuse (3,5, and 13A are the common ratings), so you can't exceed ~3000W (taking into account startup kick on many devices). Most houses are wired on a ring-main system with a 16 or 32A breaker. \$\endgroup\$ – John U Jan 11 '13 at 9:59
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    \$\begingroup\$ @RJR Your observation is true for Germany, too. In my home, most breakers are B16. There is one for the washing machine, C16 (a bit more on the slo-blo edge). I use two B10 breakers for a room with old (1 mm^2) wiring, and I have seen B20 for big appliances, too. The standard outlets in the lab at the company I work at are fitted with C16, because our bench equipment would trip B16 all the time. \$\endgroup\$ – zebonaut Jan 11 '13 at 15:37

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