Race to the bottom

[Dave Plowman (News]

But lower frequency means less line loss?

[Fredxx]

Inductance of long lines may be less of an issue but where this is offset by capacitors will be correspondingly smaller.

I guess the real gain will be reduced dielectric loss in underground power cables.

I don't believe power conductors are big enough for skin effects to be significant. In deep bar rotor type motors the magnetic material surrounding the conductor amplifies the skin effect where rotor resistance is a strong function of slip.

[Fredxx]

Please do explain.

[Fredxx]

Many US properties are also fed with 2-phase which gives them 208V for higher power devices. Usually where a transformer is shared amongst a number of properties. Same as 2-phase supplied to a house in the UK, for when 1 phase doesn't supply sufficient power.

240V centre tapped is not, in UK parlance. 2-phase, any more than centre tapped 110V used for tools is 2-phase. It may well be in lesser territories.

So, when you said, "A 2 phase supply in the UK isn't done the same way as the USA does it", it was a blatant lie.

[Paul]

An example of deriving 208V is shown on page 7 here.

On the street I live on, this cannot be done, since three phase is not distributed on poles in residential areas. The design of the pole height in the right-of-way, means there isn't room to safely run three=phase wire on those poles.

Only areas zoned industrial, get the full three-phase treatment and then you got your deltas and your wyes, as you desire.

One of the complaints from people owning 12 foot long Westbend lathes in their basement, is they cannot convince the power company to give them what they want. And in some cases, people have resorted to motor-generator sets to get the flavor of power they want.

So I think it's more than just my street, that does not have three phase on the pole.

Another peculiarity here, is when there is three-phase, it seems to be implemented with three separate can-format transformers, rather than the integrated rectangular pole mount with the three terminals on the top. But I have not carried out a survey of one of our industrial sectors, to see what they use in there. (Our idea of an industrial sector, is "junk yards" :-) Oh, and seamless eavestrough. The zoning may be industrial, but the activity can be pretty low-class. This is not Sarnia or Hamilton.)

Even if you see three-phase out your bedroom window, and can "almost reach out and touch it", does not mean the power company will run a connection for you. They are not accommodating in that sense. The limit of their largess, is giving you a high-power single-phase transformer upgrade, on demand.

One reason we have zoning, is to keep industrial activity out of bedroom communities. And this is something the city is not doing a very good job at. The house next door to me, is carrying out commercial activity. A house up the street has an 11 ton truck parked in the drive all day long (and various heavy equipment in a "big" garage in the back yard. A bicycle repair guy tried to fight the city, to continue running his business from his house (his garage is full of bicycles when the door opens). A small courier operation, the house drive is filled with Ford Transit vans. The community is filled with villains now. But villains on single-phase power,

110/220.

One home that was operating as a custom computer build operation, got forced out of business for not having a business license and being in a residential area. It's a never ending battle to keep cheapskates out of houses. On garbage day, compared to the other houses on that street, there were a ton of computer component boxes to be recycled. The basement windows had iron bars welded over, to prevent B&E theft.

So in a way, it's a good thing three-phase power is not available in homes here, as it dissuades metal banging and machine shops from sprouting :-) Nobody wants to pay the business license fee, or lease in the industrial sector. And parking your 11 ton truck in a residential area, is so so much fun.

Paul

[Fredxx]

What you are saying is you don't understand how 208V is derived.

I can assure you it is from 2-phases of a 3-phase 120V supply. It is also worthwhile pointing out that in common parlance that is not called a centre-tapped supply.

Quite, and in the US transformers can also be shared, though with fewer customers per transformer.

You said, "A 2 phase supply in the UK isn't done the same way as the USA does it".

That has nothing to do with, "A 2 phase supply in the UK isn't done the same way as the USA does it".

I have never questioned there is less sharing of transformers in the US. However a 2-phase supply is just that and that a statement "A 2 phase supply in the UK isn't done the same way as the USA does it" is simply wrong.

[Max Demian]

Does anyone in the UK have a 2 phase supply? If so, what is the voltage and what is it use for?

The Wiki article of world voltages certainly includes 208V as a possible US figure, so they must "cheat" sometimes. I suspect that US appliances allow for the possibility in their specifications.

[The Natural Philosopher]

Oh dear.

Perhaps something written by people who know more than you will help?

Probably not.

[The Natural Philosopher]

US is complex. In general each house is fed from a center tapped *single phase* with centre tap grounded. That gives you a 110v-0-110v output with a possibility of 220V across the two 'hots'.

In light industrial and industrial premises true 3 phase is fitted just as here. And, just as here, the voltage on 3 phase is not twice the single phase voltage but a bit less - in the UK 415v instead of 480, in the USA 208V instead of 220V.

Why they do this I do not know. But that is how it is done.,

[Max Demian]

It's just taking a connection across two phases of the 120 volt-per-phase supply.

In the house I grew up in (in a residential area) the house was connected to two wires of the four, one above the other, in poles that ran along a footpath the other side of a wall. I don't remember which wires they were. Would the neutral have been at the top, for safety? I expect the earth for the house was connected to the mains water pipes.

Often such an arrangement had a bundle of telephone wires under the four.

[charles]

My house is fed with 2 phases, although only one is in use.

[Fredxx]

If you read my post carefully you will see how I qualified the occasions where 3-phase enters a building where two of the 3 are used for when high power is required.

There are circumstances where 2-phases of a 3-phase is used in residential areas. This forum post says it's quite common in apartments:

Given your reply earlier, "A 2 phase supply in the UK isn't done the same way as the USA does it" where I hadn't mentions phase just goes to show your ignorance on the subject.

But some residential property do get 2 of those 3 phases.

No, just trying to explain to you that when you say, "A 2 phase supply in the UK isn't done the same way as the USA does it", it was an explanation of your ignorance.

Excellent, sometimes these transformers are 3 phase and 2 phases are routed into properties to give you 208V across conductors.

No, you mentioned phases, presumable through your own confusion, when I said, "Given the norm is 240V split either side of neutral/ground it can't be much different to the UK".

So why make the post you did if it wasn't out of ignorance?

Yet when I mentioned 240V you said, "A 2 phase supply in the UK isn't done the same way as the USA does it."

Anyway, we have ascertained that some US residential properties are fed with 2-phase from a 3-phase supply.

If you still want to claim this never happens in US residential properties then keep proving the ignoramus you truly are.

[Fredxx]

I can't see a passage that says that 2-phases are never supplied to residential properties?

Are you also saying in a UK DIY group that you would call a split 240V supply centred on ground is a 2-phase supply?

The article cites 208V across phases? What are you trying to say?

[Dave Plowman (News]

My parent's house, built in the 30s, had two incoming phases, but only one used. Explanation I was given was to allow electric central heating to be fitted later.

[Fredxx]

At last recognition it is done in the US in a residential setting. We've moved a long way.

Are you now saying that a 240V supply split either side of ground/neutral is a 2-phase supply?

And I said "Given the norm is 240V split either side of neutral/ground it can't be much different to the UK?" Nothing to do with houses or phases.

Just correcting mistruths and lies.

[Paul]

It's single-phase center-tapped, 113V at the mast between a Hot and a Neutral. That allows for some voltage drop from the pole and lines in the right-of-way on the property (2V drop). From hot to hot is then 230V nominal, 226V measured.

single-phase, center-tapped, house side

-------\ || /---------- Hot1 / || \ \ || /---------- Neutral / || \

-------\ || /---------- Hot2

Street House (SafetyGround)

Mine right now is on the high side, and is non-compliant.

The measured value at the moment (I have a Kill-O-Watt in the room) is 121.5V between hot and neutral. Which is just outside the acceptable range.

And they know what the voltage is that I'm reading, as each house (no exceptions) has the same digital meter with radio transmitter, and store-and-forward mesh network design. They get regular updates on units used, voltage, power factor and so on. The people at that power company, they know that the distribution of my power is done improperly. But I'm not phoning them up any more. They know, and that is where my responsibility ends. I can't "push a piece of string". They tried to fix the distribution one evening, the project was an engineering fail, and they had to undo their mod and return to the broken operating condition (too much Delta_V from end to end on the street distribution spur).

Paul

[Fredxx]

I thought US and Canada has a 6% tolerance on their 120V supply, so 113V to 127V?

[The Natural Philosopher]

No, they a not. 2 phase supplies are at least light industrial like a farm. you are wrong and wriggling. Why not fess up and have done with it?

[The Natural Philosopher]

That is because they say instead that they are supplied to light industrial and commercial properties only

No, you are.

That that is what is true two phase.

If its 240v its split single phase. If its 208v its true two phase.

No US homes are fed 208V.

I cant work out whether you are just a stupid egotists a professional troll or just plain stupid.

The plonk button is looming

[The Natural Philosopher]

No, you didnt say that You claimed it was tow separate phases. And its nothing like UK.

No, just mindless nit picking and bare faced lying