Two phases to house - loss of neutral

Actually, the Neutral conductors are *NOT* connected to the plumbing system. The Neutral conductor is connected by the MEN link to the main earthing conductor, which is connected to the appropriate earth electrode. 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).

David

I witnessed potentially expensive neutral problems twice, once while living in Hawaii, and once at my present location in North Carolina. In Hawaii the house I was staying in had to be fumigated and while the workers were tenting the house, they managed to break a partially corroded-thru neutral wire coming from the power pole, which no one noticed. Upon moving back into the house, the recently-new refrigerator died a quick death upon being plugged back in, upon which an electrician was called in, who quickly located the broken neutral.

The second time was when I'd been living where I am now, and I'd recently bought a new fridge - after a few months having it working fine I noticed it was sounding like it was struggling to start and at the same time some of the lights would get brighter (I guess they were on the other half of the 240V supply). Not wanting to have to deal with a dead fridge again, I investigated the incoming power panel and found the neutral to be rather lose, so I coated it and the other 2 incoming wires with some Noalox (an anti-aluminum oxidation compound) and tightened 'em all goot-n-tite. That was about 7 years ago, no more problems so far.

Mike

Removing the return leg isn't going to cause problems in a properly wired US home. Don't know about the UK.

I actually had the neutral fail (break) a few years back during a winter wind-storm. No deleterious effects. The imbalance (neutral) current was carried by the ground, a copper water pipe that's probably at least 10 feet below gound level and 20 0r so feet long.

Jerry

You're *supposed* to have a bypass around the meter for just this reason, or the ground connected before the meter.

Jerry

I haven't checked a *current* CodeBook but I think connections to water pipes have to be within a few feet of the pipe's entry to the building, etc. And the water pipe must have a certain length *in* the soil, etc.

Buildings with metal structural members often have the building itself earthed. And, of course, rules change depending on the potential available on each conductor, etc.

But, as I said, I think this is all deprecated as you can't

Except where plastic is in use. Mine is all plastic and the safety earth is linked to the armouring on the incoming mains feed cable.

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.

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.

Is this something new(

I said I have two phases.

Sylvia.

Sometimes, just to make things really exciting, some of the neutral current flows over alternate paths to a neighbor's house. These alternate paths can include things like cable TV shields.

On 11/23/2009 7:43 PM D Yuniskis spake thus:

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.

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.

Sylvia Else Inscribed thus:

Yes I know ! I answered the question above !

You think I'm mistaken about having two phases?

Sylvia.

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.

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

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.

I don't like dealing with the *tar*. :<

Are you really thick or just pretending.