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I actually have 3 phase in my home. Notes you said it was not possible. Not sure why, but it is here. Why would anyone ever want it?

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Where do you live (country) and is this an apartment building? –  Fiasco Labs Jul 30 '13 at 5:39
What makes you think you have 3 phase? What kind of connection (outlet) is it? –  Elliott B Jul 30 '13 at 5:56
Sometimes you'll have equipment designed for three phases. Those are very powerful heaters, very powerful AC systems and industrial equipment (such as an industrial sewing machine) induction motors. –  sharptooth Jul 30 '13 at 9:26

2 Answers 2

Here's an example:

My home was provided with a three-phase supply when it was built in 1990 because the builder intended to install an electrical storage-heating system.

I bought the house before the heating system was installed and opted for an oil-fired system instead.

So, in my area, it's an option you can request from the power company if you have a specific need for it.

So far as I know, three-phase supply is commonly used for equipment that requires substantially more power than most domestic household appliances. Some industrial electric motors require a three phase supply. In my area a single phase is 230 V so domestic households almost always use only a single phase. I expect the phases are separated at the local substation where high voltage local distribution is reduced to 230 V.

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Plus 3-phase motors are more efficient and self starting without extra circuitry. –  Fiasco Labs Jul 30 '13 at 18:44

Three phase power distribution is used in cases, such as industrial setups, where large motors or other loads are attached to the AC power mains. The advantage of 3-phase over single or two phase is that more net power can be delivered to the load over a 3-phase system for a given conductor size.

If you happen to actually have 3-phase power delivered to your site then it is possible that a previous owner or site occupant had loads of the type that demanded the more efficient power transmission.

Three phase power installations use a different type of main load center distribution panel than a single or dual phase system. Thus it is not a good idea to even think of mixing the two.

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Three phase systems are also useful for lighting when you need to mitigate against the stroboscopic "Wagon-Wheel" effect, where high-speed rotating objects appear to have a different rotation direction/speed (or even appear stationary) –  MrJamin Jul 31 '13 at 11:50

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