Whilst as a consumer you should never connect "Protective Ground" and "Neutral" in the UK supply chain this is common.
So whilst we have separate "ground/earth" and "neutral" wires in the house wiring and in the wall sockets etc. in many new supply systems we also have "Protective Multiple Earthing" which means that a single conductor in the supply line from substation to premises serves as both "Earth" and "Neutral", and the internal earth and neutral are both connected to this on entry to the house. In these systems it is important not to separately connect the internal "Earth" or "Ground" to the real ground, and to ensure that all exposed metal work in the premises is "earth bonded". This can cause Radio Hams like myself real problems as you can' put a separate earth on a radio transmitter. I think this is basically covered here:- http://en.wikipedia.org/wiki/Earthing_system Dave Wade G4UGM Illegitimi Non Carborundum > -----Original Message----- > From: The IBM z/VM Operating System [mailto:[email protected]] On > Behalf Of Kris Buelens > Sent: 04 May 2009 19:09 > To: [email protected] > Subject: Re: z890 power: 3 phase vs 1 phase? > > You are perfectly right: the same here in Belgium: neutral is the > middle of the 380 3ph, it should never be grounded; 1 ph + neutral > gives 240V (used to be 220V >30 years ago). To get 3ph 380 at home > one needs to convince the power distributor otherwise one gets 1 ph + > neutral only. > > 2009/5/4 Bruce Hayden <[email protected]>: > > Lots of discussion on this.. I'm no expert, but it didn't sound > > right. I found 2 relevant articles on Wikipedia: > > http://en.wikipedia.org/wiki/Three-phase_electric_power > > http://en.wikipedia.org/wiki/Split_phase > > > > So, your dryer, oven, etc. in a U.S. home runs on split phase power, > > *not* 3 phase. (2 phase power is not the same as split phase.) And > > your reference to "ground" should be "neutral". The ground wire > > should never carry a current - if it does, then you have a problem. > > It is there for safety. The neutral wire (I've heard it called the > > "grounded conductor") can carry current for loads that require a > > single phase. > > > > I agree with what you said about 3 phase in commercial installations. > > > > Note: My experience is only the U.S.A. - what you say may be true for > the U.K. > > > > On Mon, May 4, 2009 at 12:52 PM, Dave Wade <[email protected]> > wrote: > >> 2 Live + ground is two phase. A three phase supplies doesn't need a > ground, > >> but usually one is provided to allow single phase equipment to be used. > >> > >> > >> > >> Power is generated by three phase alternators and these expect the load > on > >> each phase to be identical. > >> > >> > >> > >> So in most areas of buildings where high power is used (e.g. a large > machine > >> room or server centre) there will be outlets connected to each of the > three > >> phases and attempts made to balance the load across the phases. > >> > >> > >> > >> Certainly in the UK using the power in an unbalanced way may result in > >> financial penalties. > >> > >> > >> > >> Typically three phase equipment performs the balancing internally so > are > >> "desirable" from the suppliers point of view. > >> > >> > >> > >> Even when we ran 4381's we still had a mix of three phase and single > phase, > >> but of course we are on 22volts. I don't think there is any three phase > >> stuff left in our machine room any more. > >> > >> > >> > >> Dave Wade G4UGM > >> > >> Illegitimi Non Carborundum > >> > >> > >> > >> -----Original Message----- > >> From: The IBM z/VM Operating System [mailto:[email protected]] On > >> Behalf Of John Harris > >> Sent: 04 May 2009 17:05 > >> To: [email protected] > >> Subject: Re: z890 power: 3 phase vs 1 phase? > >> > >> > >> > >> The main difference between single phase and 3-phase (basically a > ground and > >> 2 live circuits) is the resultant voltage. > >> > >> Single-phase = 110v US and 220v UK > >> > >> 3-Phase = 220v US and 385v UK > >> > >> All heavy duty applicances in the US (A/Cs, Washer/Dryers, Electrical > >> cooktops etc) use 220v,(3phase). > >> > >> By supporting 3-phase, appliances can run in a multi-tude countries and > the > >> manufacturer only has to worry about the frequency i.e. 50/60hz between > the > >> regions. > >> > >> I had one pulled into my garage for my 220v tools. > >> > >> My 2-cents worth > >> > >> John Harris > >> > >> IBM > >> > >> ------ Original Message ------ > >> Received: 11:37 AM EDT, 05/04/2009 > >> From: Dave Jones <[email protected]> > >> To: [email protected] > >> Subject: Re: z890 power: 3 phase vs 1 phase? > >> > >> That's right...the z boxes basically have an a/c system built into > them. > >> The a/c units here at the house (living here in Houston, we know a > >> thing or two about a/c....) both run on three phase power. > >> > >> Alan Altmark wrote: > >>> On Monday, 05/04/2009 at 08:57 EDT, Dave Jones <d...@vsoft- > software.com> > >>> wrote: > >>>> Well, the z boxes all have motors to drive the fans, but I do not > >>>> understand why they would need 3 phase power..... > >>> > >>> Don't forget the coolant compressors. > >>> > >>> Alan Altmark > >>> z/VM Development > >>> IBM Endicott > >> > >> -- > >> Dave Jones > >> V/Soft > >> www.vsoft-software.com > >> Houston, TX > >> 281.578.7544 > >> > >> > > > > > > > > -- > > Bruce Hayden > > Linux on System z Advanced Technical Support > > IBM, Endicott, NY > > > > > > -- > Kris Buelens, > IBM Belgium, VM customer support
