Two phases to house - loss of neutral
in [Repair]
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From: Sylvia Else on 25 Nov 2009 19:58 Trevor Wilson wrote: > "Sylvia Else" <sylvia(a)not.at.this.address> wrote in message > news:01059875$0$23368$c3e8da3(a)news.astraweb.com... >> Baron wrote: >>> Meat Plow wrote: >>> >>>> On Tue, 24 Nov 2009 11:10:26 +1100, Sylvia Else >>>> <sylvia(a)not.at.this.address>wrote: >>>> >>>>> I have to phases of power supply to my house - so three power lines, >>>>> two phases plus neutral. >>>>> >>>>> I've on occasion wondered what would happen if we lost the neutral >>>>> line. It seems to me that we'd then have the voltage between the two >>>>> phases across two sets of appliances, one set attached to one phase, >>>>> and the other set attached to the other phase, with the two sets in >>>>> series as a result of their common connection to the neutral wire. >>>>> Since the two sets are unlikely to represent equal loads, the net >>>>> result would be a large overvoltage on one set of appliances. >>>>> >>>>> My electrician says it's not an issue, but I can't see why. >>>>> >>>>> Any thoughts? >>>>> >>>>> Sylvia. >>>> Removing the return leg isn't going to cause problems in a properly >>>> wired US home. Don't know about the UK. >>> The lights would go out ! Domestic properties usually have just a 240v >>> single phase feed. Usually you would get a single phase running down >>> one side of the street and another phase running down the other. >>> >> I said I have two phases. > > **You are, at this time, discovering the futility of asking a question that > is specific to Australia, in an international group. Oh, I don't know. I've learnt a fair bit in the process. Those in the US who really have a split single phase rather than two phases, would experience much the same effects if they lost the centre (neutral) link back to the transformer. Sylvia.
From: Jamie on 25 Nov 2009 20:24 Sylvia Else wrote: > Trevor Wilson wrote: > >> "Sylvia Else" <sylvia(a)not.at.this.address> wrote in message >> news:01059875$0$23368$c3e8da3(a)news.astraweb.com... >> >>> Baron wrote: >>> >>>> Meat Plow wrote: >>>> >>>>> On Tue, 24 Nov 2009 11:10:26 +1100, Sylvia Else >>>>> <sylvia(a)not.at.this.address>wrote: >>>>> >>>>>> I have to phases of power supply to my house - so three power lines, >>>>>> two phases plus neutral. >>>>>> >>>>>> I've on occasion wondered what would happen if we lost the neutral >>>>>> line. It seems to me that we'd then have the voltage between the two >>>>>> phases across two sets of appliances, one set attached to one phase, >>>>>> and the other set attached to the other phase, with the two sets in >>>>>> series as a result of their common connection to the neutral wire. >>>>>> Since the two sets are unlikely to represent equal loads, the net >>>>>> result would be a large overvoltage on one set of appliances. >>>>>> >>>>>> My electrician says it's not an issue, but I can't see why. >>>>>> >>>>>> Any thoughts? >>>>>> >>>>>> Sylvia. >>>>> >>>>> Removing the return leg isn't going to cause problems in a properly >>>>> wired US home. Don't know about the UK. >>>> >>>> The lights would go out ! Domestic properties usually have just a 240v >>>> single phase feed. Usually you would get a single phase running down >>>> one side of the street and another phase running down the other. >>>> >>> I said I have two phases. >> >> >> **You are, at this time, discovering the futility of asking a question >> that is specific to Australia, in an international group. > > > Oh, I don't know. I've learnt a fair bit in the process. > > Those in the US who really have a split single phase rather than two > phases, would experience much the same effects if they lost the centre > (neutral) link back to the transformer. > > Sylvia. Yes we would, and it's a very exciting effect! ;)
From: PeterD on 25 Nov 2009 20:14 On Wed, 25 Nov 2009 17:28:50 -0700, D Yuniskis <not.going.to.be(a)seen.com> wrote: >Hi Sylvia, > >Sylvia Else wrote: >>> Are you really thick or just pretending. >> >> I'll opt for neither. So far you've said nothing relevant to the thread, >> which concerns a house with two connected phases. > >Have we decided that you really have two different *phases* >vs. two different *legs* (but really "single phase" -- think >center tapped transformer). > >E.g., 3 phase "220" (US) is three conductors plus a ground. >If you look at any two of those conductors (ground referenced) >you would see a 120 degree PHASE lag between them. > >A US residential service is "single phase, 220" in which >you have two 110V circuits ("legs") 180 degrees out of phase >with each other (i.e., the center tapped xformer concept). > >So, here, half of your lighting/living circuits are on >one *leg* (so those appliances are nominally 110VAC) >and the other half on the other "leg". Some bigger >loads tend to straddle both legs (220) -- e.g., the >blower motor in the evaporative cooler. Other >appliances *use* both legs but actually as two 110V >*circuits* (i.e., higher ampacity available on two >conductors). > US standard is 240 volts, not 220.
From: D Yuniskis on 25 Nov 2009 20:32 PeterD wrote: > On Wed, 25 Nov 2009 17:28:50 -0700, D Yuniskis > <not.going.to.be(a)seen.com> wrote: > >> Hi Sylvia, >> >> Sylvia Else wrote: >>>> Are you really thick or just pretending. >>> I'll opt for neither. So far you've said nothing relevant to the thread, >>> which concerns a house with two connected phases. >> Have we decided that you really have two different *phases* >> vs. two different *legs* (but really "single phase" -- think >> center tapped transformer). >> >> E.g., 3 phase "220" (US) is three conductors plus a ground. >> If you look at any two of those conductors (ground referenced) >> you would see a 120 degree PHASE lag between them. >> >> A US residential service is "single phase, 220" in which >> you have two 110V circuits ("legs") 180 degrees out of phase >> with each other (i.e., the center tapped xformer concept). >> >> So, here, half of your lighting/living circuits are on >> one *leg* (so those appliances are nominally 110VAC) >> and the other half on the other "leg". Some bigger >> loads tend to straddle both legs (220) -- e.g., the >> blower motor in the evaporative cooler. Other >> appliances *use* both legs but actually as two 110V >> *circuits* (i.e., higher ampacity available on two >> conductors). >> > > US standard is 240 volts, not 220. If we want to be *pedantic*, there are LOTS of "little errors" in this discussion! ;-)
From: D Yuniskis on 25 Nov 2009 20:35
Sylvia Else wrote: > D Yuniskis wrote: >> Have we decided that you really have two different *phases* >> vs. two different *legs* (but really "single phase" -- think >> center tapped transformer). > > Four wires on the power poles in the street, being a three phase supply. > We have three wires leading from the street, and two power meters, plus > a third meter for the off peak water supply. I'll ignore the comment about power meters as you can get power meters with all sorts of internal topologies (i.e., I can't deduce anything from that). So, does *your* house have "phases" A and B dropped to it; your neighbor gets B & C; *his* neighbor C & A; the large *business* at the end of the block A B & C, etc.? I.e. what criteria are used to determine *who* is connected to *what*? |