Two phases to house - loss of neutral
in [Repair]
|
From: Sylvia Else on 25 Nov 2009 05:51 baron wrote: > Sylvia Else Inscribed thus: > >> Baron wrote: > >>>> 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. >> >> Sylvia. > > Yes I know ! I answered the question above ! > You think I'm mistaken about having two phases? Sylvia.
From: David on 25 Nov 2009 07:10 Phil Allison the unqualified drop out wrote: > >> Actually, the Neutral conductors are *NOT* connected to the plumbing >> system. ** Wot INSANE CRAPOLOGY !! > >> The Neutral conductor is connected by the MEN link to the main earthing >> conductor, which is connected to the appropriate earth electrode. > > ** Da knee bone's connected to da thigh bone .... But the Neutral not connected to the water pipe.... > > >> AS/NZS 3000 then requires that conductive pipe work be equipotentially >> bonded to the main earth conductor or earth terminal or bar (NOT to the >> neutral). > > This should explain it for you Phil. Not too technical. http://www.standards.org.au/downloads/080725_Electrical_Earthing_Standards_Alert.pdf David
From: whit3rd on 25 Nov 2009 15:10 On Nov 24, 7:54 am, Meat Plow <m...(a)petitmorte.net> wrote: > Removing the return leg isn't going to cause problems in a properly > wired US home. Don't know about the UK. That's just false. A properly wired US home without a neutral wire to the transformer has 240V across both phases, which can leave either phase anywhere from zero to 240 VAC. Damage to 120V appliances will result unless the breakers trip first. The 'ground' connection would have to carry the whole house's current imbalance load in place of that neutral, through the earth to some nearby dwelling that DOES have a proper neutral wire, to the same pole-pig transformer, for this calamity not to occur.
From: Jerry Peters on 25 Nov 2009 16:23 whit3rd <whit3rd(a)gmail.com> wrote: > On Nov 23, 5:38�pm, D Yuniskis <not.going.to...(a)seen.com> wrote: > >> Grounding the mains to "plumbing" *was* common in the US many >> years ago. �Now, I believe, you *must* ground to a metal >> rod driven into the earth (8 ft?). > > Just to be clear, my copy of the US National Electric Code clearly > requires (section 250-80) plumbing to be bonded to the electrical > service > ground, it just doesn't allow the buried water piping to substitute > for > a ground rod or similar to-the-soil connection. > > The ground wire from the interior water pipe grounds the pipes, not > the > electric wiring. Maybe no, but certainly not 60 years ago when my house was built. Grounding via the water supply pipe was resonably standard then. The problem now is that the water supply pipe is likely to be plastic, or perhaps partly replaced by plastic. Also the water main is very likely to be plastic if it's relatively new. Jerry
From: D Yuniskis on 25 Nov 2009 16:35
David Nebenzahl wrote: > On 11/23/2009 7:43 PM D Yuniskis spake thus: > >> Phil Allison wrote: > > >>> ** In the US and Canada - it is NOT permitted to link neutral >>> and earth or plumbing within a premises. >> >> "*within* a premises". The neutral *is* "earthed" right outside >> the home, typically. The Code goes to great lengths telling >> you exactly *how* to earth the mains at the service entrance. >> >> However, this ignores the fact that most residential wiring >> is grandfathered into "acceptance". Previously, homes *were* >> grounded through their "water main" (e.g., my parents home >> has ground at the water meter). > > Grounding a home's electrical system through the plumbing is perfectly > safe, and probably the best way to do it, assuming the plumbing is steel > or copper. > > This is no longer permitted according to the NEC (American electrical > code). Why? Because not all pipe nowadays is steel or copper. In fact, > one can get into great trouble replumbing part of a house with plastic > and severing an old ground connection. The water utility (and plumber) doesn't care about how "good" a ground their water supply is. You get what you get. OTOH, by *explicitly* mandating that you earth the mains with an "8 ft rod" (of specific characteristics), you focus on the ground itself -- as opposed to relying on ground as a "side effect" of your plumbing! E.g., I have seen several neighbors have their water service replumbed from house to street (meter is at the street, here). Had they relied on water main for earth, they would lose electric service at the same time. Also note that in many localities, homeowners are allowed to do their own *plumbing* but aren't allowed to tamper with the mains! :> ("Gee, I didn't realize that cutting my water main to install my own water softener would cause my electric to go...") Grounding has changed a *lot* over the years. Most of the homes I worked on when I was younger were 14/2 in BX. *If* a ground was used, you often saw the BX's jacket serve that purpose (or the "drain wire" within). Nowadays, I think folks would cringe at this use. >> So, you can encounter all sorts of different situations >> here in the US (I've even worked on homes with knob & tube >> wiring!) > > I've worked on lots of knob and tube wiring around here (San Francisco > Bay area). It's actually a very good wiring system, and in most cases is > still perfectly safe and functional 60 to 80 years later. It's permitted > to be "grandfathered" in under the NEC, but of course is no longer > installed anymore. I don't like dealing with the *tar*. :< |