4 ms·

The split phase arrangement comes from Edison's DC systems. For large installations they found out that the losses were unacceptable and solved thet by running

by dfox 3y ago

The split phase arrangement comes from Edison's DC systems. For large installations they found out that the losses were unacceptable and solved thet by running the lighting on 220V with sets of two 110V bulbs in series, usually combined with some somewhat funky wiring scheme in order to even more reduce the required wiring cross-section (it is somewhat reminiscent of later British ring mains construction and strikingly similar to various arrangements for powering long LED strips). This is also the reason why it is somewhat common for the US commercial lighting to use 220V. Three phase for residental connection is pretty much a standard everywhere with 230/400V system. Only small flats and really small houses get single phase. This is because the 230/400V output of the larger distribution transformer is inherently threephase and this gets distributed to essentially all the points of connection and the only reason why there are single phase residental connection is that they are slightly cheaper (both in terms of fixed monthly payment for capacity and in terms of initial installation costs). While in US the input to the typical residental pole/pedestal mounted local distribution transformer is already single phase, so you cannot really get three phases without running additional wires to the substation (and probably also having you own dedicated distribution transformer) and thus in a residantal area you are simply stuck with split-phase.

MrBuddyCasino 3y ago
Another thing Americans miss out on - the "boost" function on modern induction stoves. Since the oven usually gets one phase and the cooking fields get two dedicated phases of the 400V lines, you can use "boost" to steal power from the other phase. Water boils even faster than in a tea kettle!
- andersa 3y ago
  Sure would be nice to have some kind of hyper boost setting. There's a 3 phase connection, so why don't they use it? Time to heat that one pot of water with 11 kW.
  - Ekaros 3y ago
    Having 3 different inducting circuits would be hard to fit and make less even heating distribution. Also I think they would induct to each other. Also 11 kW could be dangerous with empty containers that is quite a bit of power. Like resistive heaters get red hot at lower power.
    - andersa 3y ago
      There are actually some stoves out there that can use two phases for one large pot, reaching 7.2kW. For example, Miele stoves with the "PowerFlex" feature do this (that is quite the big brain name given the context). Since it is possible to do for two phases, why wouldn't it also work for 3? More power!
  - deleted 3y ago
    [deleted]
  - dtgriscom 3y ago
    More power! https://www.youtube.com/watch?v=kBNPAJLhKZ4 https://www.youtube.com/watch?v=kBNPAJLhKZ4
- Kirby64 3y ago
  What do you mean? Comparing a UK Bosch induction hob with a US one, they both seem to offer roughly 2.5kW of power in normal mode, and both offers a "boost" functionality that boosts the output temporarily to 3.6kW. Stove outlets can handle 12kW in the US... So there's plenty of power to go around. Built in outlets can go even higher, with 240V/60A being somewhat common for larger appliances.
  - MrBuddyCasino 3y ago
    It is hard to find numbers, but combining phases is definitely how it works for some models, eg Miele PowerFlex uses "booster output of up to 7.4 kW" [0]. This is why you can only use it for one field. > Stove outlets can handle 12kW wasn't aware, in that case I was wrong, good for them [0] https://www.miele.co.th/domestic/1512.htm?&&&info=200004302-ZST https://www.miele.co.th/domestic/1512.htm?&&&info=200004302-...
- sbradford26 3y ago
  American induction cooktops also have boost functionality. All boost does is temporarily increases the power output usually at the expense of other elements. Power isn't "stolen" from other phases. Usually the reason why the cooktop cannot be in boost mode the entire time is cooling related. https://www.subzero-wolf.com/assistance/answers/wolf/common/inductioncooktop-power-boost-feature https://www.subzero-wolf.com/assistance/answers/wolf/common/...
- chinchilla2020 3y ago
  It's just increasing the power draw. There is no concept of 'stealing power from another phase'
bruckie 3y ago
> solved thet by running the lighting on 220V with sets of two 110V bulbs in series Sounds like an exciting day when one of your bulbs burns out!
- bitdivision 3y ago
  Bulbs normally burn out open, breaking the circuit. And in the unusual case that they don't, I would imagine the thin wires leading to the filament will melt, also breaking the circuit. And if all else fails you your circuit breaker should flip. If bulbs normally failed short, then you'd have circuit breaker's flipping a lot more often.
  - eythian 3y ago
    They can be a little spectacular when they fail short. My last incandescent (a bathroom light) did it a few weeks ago, exploding the glass of the bulb and popping the breaker for my downstairs circuit.
- jefftk 3y ago
  Why? A burned-out bulb fails open not closed. If it failed closed then a bulb burning out would trip the circuit breaker.
  - sokoloff 3y ago
    > Why? A burned-out bulb fails closed not open. In electrical circuit terminology, "open" means "not connected" while "closed" means "connected/shorted". That's different from direct translation of Chinese (and I think several European languages) where "open the light" means to turn it on (by closing the circuit, naturally). I think it's most common English engineering usage (by far) to say that a burned out lamp fails open [circuit].
    - jefftk 3y ago
      Whoops, sorry, I had them reversed!
sokoloff 3y ago
> solved thet by running the lighting on 220V with sets of two 110V bulbs in series A related tip is to build a "dim bulb tester" to help you diagnose short circuits on mains-powered equipment. I have a traditional incandescent lightbulb in a porcelain socket wired in series with an outlet (and a switch). A non-shorted load will tend to work pretty well as the cold/cool incandescent bulb is fairly low resistance in series with the load. A shorted load will light up the light bulb brightly but not trip any breakers, allowing the opportunity to do some troubleshooting on the bench. I've also used this concept several times to find short circuits in house wiring. Put the dim bulb tester in series with the circuit that's shorted and then, using a non-contact voltage tester, find where the measurement on the NCVT changes. That's likely where your short is. In building such a device, you're on your own liability-wise; please don't be dumb.
- mindslight 3y ago
  When I was a kid, I (ab)used this trick by wiring around a dozen 100 watt bulbs in parallel, between the line and a "probe". It was great fun for zapping whatever I wanted, writing stuff on metal, etc. In retrospect the biggest safety issue I missed was the light from the arc.

by dfox 3y ago

MrBuddyCasino 3y ago

Another thing Americans miss out on - the "boost" function on modern induction stoves. Since the oven usually gets one phase and the cooking fields get two dedicated phases of the 400V lines, you can use "boost" to steal power from the other phase. Water boils even faster than in a tea kettle!

andersa 3y ago
Sure would be nice to have some kind of hyper boost setting. There's a 3 phase connection, so why don't they use it? Time to heat that one pot of water with 11 kW.
- Ekaros 3y ago
  Having 3 different inducting circuits would be hard to fit and make less even heating distribution. Also I think they would induct to each other. Also 11 kW could be dangerous with empty containers that is quite a bit of power. Like resistive heaters get red hot at lower power.
  - andersa 3y ago
    There are actually some stoves out there that can use two phases for one large pot, reaching 7.2kW. For example, Miele stoves with the "PowerFlex" feature do this (that is quite the big brain name given the context). Since it is possible to do for two phases, why wouldn't it also work for 3? More power!
- deleted 3y ago
  [deleted]
- dtgriscom 3y ago
  More power! https://www.youtube.com/watch?v=kBNPAJLhKZ4 https://www.youtube.com/watch?v=kBNPAJLhKZ4
Kirby64 3y ago
What do you mean? Comparing a UK Bosch induction hob with a US one, they both seem to offer roughly 2.5kW of power in normal mode, and both offers a "boost" functionality that boosts the output temporarily to 3.6kW. Stove outlets can handle 12kW in the US... So there's plenty of power to go around. Built in outlets can go even higher, with 240V/60A being somewhat common for larger appliances.
- MrBuddyCasino 3y ago
  It is hard to find numbers, but combining phases is definitely how it works for some models, eg Miele PowerFlex uses "booster output of up to 7.4 kW" [0]. This is why you can only use it for one field. > Stove outlets can handle 12kW wasn't aware, in that case I was wrong, good for them [0] https://www.miele.co.th/domestic/1512.htm?&&&info=200004302-ZST https://www.miele.co.th/domestic/1512.htm?&&&info=200004302-...
sbradford26 3y ago
American induction cooktops also have boost functionality. All boost does is temporarily increases the power output usually at the expense of other elements. Power isn't "stolen" from other phases. Usually the reason why the cooktop cannot be in boost mode the entire time is cooling related. https://www.subzero-wolf.com/assistance/answers/wolf/common/inductioncooktop-power-boost-feature https://www.subzero-wolf.com/assistance/answers/wolf/common/...
chinchilla2020 3y ago
It's just increasing the power draw. There is no concept of 'stealing power from another phase'

bruckie 3y ago

> solved thet by running the lighting on 220V with sets of two 110V bulbs in series Sounds like an exciting day when one of your bulbs burns out!

bitdivision 3y ago
Bulbs normally burn out open, breaking the circuit. And in the unusual case that they don't, I would imagine the thin wires leading to the filament will melt, also breaking the circuit. And if all else fails you your circuit breaker should flip. If bulbs normally failed short, then you'd have circuit breaker's flipping a lot more often.
- eythian 3y ago
  They can be a little spectacular when they fail short. My last incandescent (a bathroom light) did it a few weeks ago, exploding the glass of the bulb and popping the breaker for my downstairs circuit.
jefftk 3y ago
Why? A burned-out bulb fails open not closed. If it failed closed then a bulb burning out would trip the circuit breaker.
- sokoloff 3y ago
  > Why? A burned-out bulb fails closed not open. In electrical circuit terminology, "open" means "not connected" while "closed" means "connected/shorted". That's different from direct translation of Chinese (and I think several European languages) where "open the light" means to turn it on (by closing the circuit, naturally). I think it's most common English engineering usage (by far) to say that a burned out lamp fails open [circuit].
  - jefftk 3y ago
    Whoops, sorry, I had them reversed!

sokoloff 3y ago

> solved thet by running the lighting on 220V with sets of two 110V bulbs in series A related tip is to build a "dim bulb tester" to help you diagnose short circuits on mains-powered equipment. I have a traditional incandescent lightbulb in a porcelain socket wired in series with an outlet (and a switch). A non-shorted load will tend to work pretty well as the cold/cool incandescent bulb is fairly low resistance in series with the load. A shorted load will light up the light bulb brightly but not trip any breakers, allowing the opportunity to do some troubleshooting on the bench. I've also used this concept several times to find short circuits in house wiring. Put the dim bulb tester in series with the circuit that's shorted and then, using a non-contact voltage tester, find where the measurement on the NCVT changes. That's likely where your short is. In building such a device, you're on your own liability-wise; please don't be dumb.

mindslight 3y ago
When I was a kid, I (ab)used this trick by wiring around a dozen 100 watt bulbs in parallel, between the line and a "probe". It was great fun for zapping whatever I wanted, writing stuff on metal, etc. In retrospect the biggest safety issue I missed was the light from the arc.