Talk:Ground and neutral

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[edit] grounding to neutral in portable appliances

im sure i have seen it mentioned on a number of sites that at some stage the north americans grounded the case of thier portable appliances to the neutral in some cases. There is a passing reference here at National Electrical Code (U.S.) here but i am sure i have seen it in other places.

There seem to be a lot of american sites giving stark advice against connecting appliances with polarised plugs to unpolarised outputs but little in the way of information on why. Are they merely scaremongering? or is there some other reason? Plugwash 18:56, 28 Dec 2004 (UTC)

The only place a neutral was allowed to be used as a case ground was in a stove, which at the time was permanently wired. I'm told this was an effort to save copper wire during WWII. This exemption was removed from the US code a decade or so back, but I'll have to hunt around to find the date.

As for unpolarized applicances, nearly everything with a polarized plug has a case made of plastic so there's no grounding possible anyway. Double-insulated tools require two independant insulation failures before any part of the case can contact the live circuit - these tools also come with polarized plugs. The only place I can think of this being remotely useful is for portable TV receivers where proper polarization of the plug may help prevent energizing the antenna terminals - but this is pretty far-fetched. Rest assured that in the litiginous US market, if people were being injured by non-polarized plugs, you wouldn't be able to buy them any more. --Wtshymanski 04:53, 29 Dec 2004 (UTC)

I'm prety sure that electric driers also allowed "neutral as ground" in the past.

With regard to polarised appliances in unpolarized outlets, the only way you can (practically) do that is to cut off the polarising tabs on the neutral pin of the plug. That means that the appliance will never be polarised again. This could mean that, for example, the shell of an light bulb may subsequently be both hot and unswitched, and one could easily get shocked changing the light bulb. Americans are famous for doing something dumb and then trying to find someone to sue over their own error, so the push is to try to prevent them from doing dumb things in the first place.

Atlant 15:01, 1 March 2006 (UTC)

[edit] Erroneous text?

The following:

In almost all low voltage (under 1KV) wiring with more than one phase core the neutral fits both of these definitions. and we will assume this is the case for the remainder of this article.

is just wrong. I'd like to remove it. The article needlessly confuses the functions of grounds and neutrals. --Wtshymanski 20:38, 28 Jan 2005 (UTC)

[edit] Core? What's a core?

I'm confused by the term "core" used in paragraph 3, defining Neutral. Are you talking about individual strands of wire or cabling? If so, a diagram would be helpful here. When you say "a core that acts as a common for several phase cores", do you mean that the three different strands carrying the different phases are wrapped around a central strand? If so, in such a case does the central strand provide structural integrity, or is it used to carry charges, or both, or neither? Sorry for asking such basic questions. --RCT3 17:17, 17 Feb 2005 (UTC)

a core is an insulated current carrying conductor within a cable. A core consists of one or more standard of copper covered in an insulating material.

and yes a neutral that is a common of multiple phase cores will cary current unless the system is perfectly balanced. Plugwash 20:55, 17 Feb 2005 (UTC)

It's a Europeanism. In North America, we'd typically say "conductor" instead.

Atlant 15:01, 1 March 2006 (UTC)