Usually 3 phase is delivered to a substation that splits the single phases to different streets. It does not make economic sense to put all 3 phases down every street just in case one person wants it as it adds to the cabling required. No point in the OP going frantic. You want an industrial power supply? move to an industrial location.
Someone else has noted that it's normal to take the three phases and neutral down the whole street and tap different phases at different points for different building's supplies. It's quite possible that your next door neighbour is on a different phase - something to bear in mind if you're having a party in the garden and someone decides to throw an extension cord over the fence to power the disco lights from the neighbour's mains, while you power the music from your house's mains.
You're missing the fact that the OP is in North America, where a different system prevails. Rather than picking off individual phase+neutral pairs for each property, there's a centre tapped transformer, typically every 1-3 houses (primary connected across two of the three phases), usually on a pole. This supplies two phases at 180º from each other and a neutral. Each phase is nominally 120V with respect to the neutral and 240V with respect to each other. It's normal to bring two phases and a neutral in from the transformer, and bond the neutral to earth at the distribution board. Hefty appliances get a 240V supply, others 120V.
So, three phase is a wholesale change of supply in North America, not just bringing in the missing phases. You'll need a 3 phase transformer in place of the existing two phase.
single phase, split phase is not two phase
Someone else has noted that it's normal to take the three phases and neutral down the whole street and tap different phases at different points for different building's supplies. It's quite possible that your next door neighbour is on a different phase - something to bear in mind if you're having a party in the garden and someone decides to throw an extension cord over the fence to power the disco lights from the neighbour's mains, while you power the music from your house's mains.
You're missing the fact that the OP is in North America, where a different system prevails. Rather than picking off individual phase+neutral pairs for each property, there's a centre tapped transformer, typically every 1-3 houses (primary connected across two of the three phases), usually on a pole.
This supplies two phases at 180º from each other and a neutral. Each phase is nominally 120V with respect to the neutral and 240V with respect to each other.
It's normal to bring two phases and a neutral in from the transformer, and bond the neutral to earth at the distribution board. Hefty appliances get a 240V supply, others 120V.
So, three phase is a wholesale change of supply in North America, not just bringing in the missing phases. You'll need a 3 phase transformer in place of the existing two phase.
single phase, split phase is not two phase
I think you meant to say:
Single phase, split phase is not two phases.
When being pedantic, always check your spelling, punctuation and grammar. But yes, technically you are correct.
I think you meant to say:
Single phase, split phase is not two phases.
When being pedantic, always check your spelling, punctuation and grammar. But yes, technically you are correct.
I'm no English expert but wouldn't it be ok to refer to a power system with two phases as "two phase" ?
single phase, split phase is not two phase
I think you meant to say:
Single phase, split phase is not two phases.
When being pedantic, always check your spelling, punctuation and grammar. But yes, technically you are correct.
I'm no English expert but wouldn't it be ok to refer to a power system with two phases as "two phase" ?
I think you meant to say:
Single phase, split phase is not two phases.
When being pedantic, always check your spelling, punctuation and grammar. But yes, technically you are correct.
I'm no English expert but wouldn't it be ok to refer to a power system with two phases as "two phase" ?
No, absolutely not!
Two phases would be 120° degrees apart!!
That would give you some intermediate voltage.
This is a center-tapped single phase, providing 180° separated 120-0-120
... - something to bear in mind if you're having a party in the garden and someone decides to throw an extension cord over the fence to power the disco lights from the neighbour's mains, while you power the music from your house's mains.
Wait... What?!!
Why would it matter if you use extension cords from mains supplied from different phases? You're not connecting anything across the phases or shorting them together.
Uhh, no. First of all, the pole transformer is connected from one phase to the grounded neutral, NOT across phases. Most residential streets only have one phase strung along them. The feed lines between those streets that come from distribution will have all three, and individual streets are connected to different phases to balance out the load as seen from upstream.
Somebody missed the "wink". He was taking the piss out of me (in a friendly fashion).
Practically every family house in Czechia (where I come from) or in Germany (where I live) has a 3-phase connection. It supplies electric stoves, owens, pumps, woodworking machines etc. My father has even 3-phase DIY electric mowing machine.
Somebody missed the "wink". He was taking the piss out of me (in a friendly fashion).
Nah, I saw it, but certain things that are fundamentally wrong drive me nuts, but I'm probably partially insane already anyway...
IIRC most of the mainland Europe is wired in this way.
Two phases would be 120° degrees apart!!
That would give you some intermediate voltage.
This is a center-tapped single phase, providing 180° separated 120-0-120
so what was fundamentally wrong? two-phase power has two phases, three-phase power has three phases, split-phase is a single phase because 180deg doesn't count as a seperate phase
Two phases would be 120° degrees apart!!
That would give you some intermediate voltage.
This is a center-tapped single phase, providing 180° separated 120-0-120
The center-tapped single phase creates a 2-phase system. But if you have two phases out of a 3-phase system, then those two are 120° apart. And if the power distribution is based on a 3-phase system while each phase powers a transformer with a center-tapped output, then you've basically created a 6-phase system. Of course, each house has only access to its local center-tapped single phase. BTW, some industries use special multi-phase systems with much more than three phases to power huge motors. Typically they operate dedicated multi-phase generators for that purpose as they get only a 3-phase system from the power grid.
Somebody missed the hint - disco lights on one phase, music system on the other - one generally connects the music system to the disco lights to make them flash in time. Sure, it's all fine if there are no faults or 'creative' wiring (I have seen, in real life, someone use more than one plug socket wired together to get a higher current feed out of a nominal 13A socket). I said "bear in mind" not, "this is a recipe for immediate disaster", don't blow what I said out of all proportion.
QuoteUhh, no. First of all, the pole transformer is connected from one phase to the grounded neutral, NOT across phases. Most residential streets only have one phase strung along them. The feed lines between those streets that come from distribution will have all three, and individual streets are connected to different phases to balance out the load as seen from upstream.
I stand corrected. I've always assumed, when I've seen things like this:
that all three phases were being used to keep balance. Three wires, three phases, seems natural to take the xformer primary's feeds from phase to phase.
center-tapped is not two phases, 180deg doesn't count. you don't need special generators to generate more phases as soon as you have atleast two, all other phase angles can be created with linear combinations
so what was fundamentally wrong? two-phase power has two phases, three-phase power has three phases, split-phase is a single phase because 180deg doesn't count as a seperate phase
Show me anywhere that you find a two phase supply to a site externally from the power company.
Here, there is really only one situation where you see a two-phase, 120° supply, which makes it 208 volts to your range, clothes drier, etc. (and appliances here ARE rated for 240/208 with different wattage ratings) and that is a multi-unit apartment or condo building with more than, say, about 6 units, where they have a three phase supply to the actual building, but then each unit only has a standard two-pole-style residential panel instead of a commercial-style three-phase panel, where each individual unit is connected to two of the phases, balanced by the connections to each of the various units.
You can't get an actual two-phase from the power company. You only end up with that when you run a device intended for split-phase 240 off two legs of the incoming three-phase.
center-tapped is not two phases, 180deg doesn't count. you don't need special generators to generate more phases as soon as you have atleast two, all other phase angles can be created with linear combinations
And how would you design a multi-phase motor for that? All windings have to be same and they have to be powered by the same voltage.
The center-tapped single phase creates a 2-phase system.
But if you have two phases out of a 3-phase system, then those two are 120° apart. And if the power distribution is based on a 3-phase system while each phase powers a transformer with a center-tapped output, then you've basically created a 6-phase system. Of course, each house has only access to its local center-tapped single phase. BTW, some industries use special multi-phase systems with much more than three phases to power huge motors. Typically they operate dedicated multi-phase generators for that purpose as they get only a 3-phase system from the power grid.
Not outraged at all, however I am 85% convinced that the traditional 3 phase grid is no longer appropriate, and probably wasteful a lot in terms of energy loss and all the complexity to control it these days.
Existing 3 phase generation should be converted to DC at point of generation.
The transmission grids would become 3 wire split DC, loosely regulated, with relaxed voltage control tolerances,
and regional DC storage that can support outages for short periods.
Voltage step -down and regulation would be by inverters.
Let me guess... you own a lot of stock in power semiconductor manufacturers?
Large transformers are relatively efficient, cheap and reliable.
Change that to giant inverters everywhere? Really?
Run all 3-phase induction motors off VFDs from now on?! There's a reason they work so well on three phase, the rotating currents make a continuous stream.
Long distance, high voltage transmission is a completely different animal! DC has some advantages there but the task of conversion and the conversion losses are non trivial.
Somebody missed the hint - disco lights on one phase, music system on the other - one generally connects the music system to the disco lights to make them flash in time. Sure, it's all fine if there are no faults or 'creative' wiring (I have seen, in real life, someone use more than one plug socket wired together to get a higher current feed out of a nominal 13A socket). I said "bear in mind" not, "this is a recipe for immediate disaster", don't blow what I said out of all proportion.
The only time that would be a problem would be a severe ground fault due to total lack of ground on one system and some sort of fault. Maybe this is a common occurrence over there, hence the reason that you require an RCD/GFCI on the whole premises? That wouldn't be any different, though, whether or not your neighbor is on the same phase as you or not. If one of your neutrals is lifted above ground, it doesn't really matter whether it is single or three phases, the problem is the neutral not being at ground potential, and THAT is DANGEROUS!
Here we actually ground everything. Every power pole is grounded to its own ground rod. Every service entrance is grounded to a copper water main or ground rod or ground plate, etc and bonded to the neutral at the service entrance.