question about 220v

Thanks for the response. I believe I hear the following for the 220v stuff (and I'm not talking code here, but practicality} :

1. The neutral is considered a ground return, in relation to the two hot

1. The neutral may in fact be connected to earth ground at some point along its way.

2. The 4th wire used in some setups is somewhat redundant, as it could also be incorporated in with the neutral, thereby eliminating the need for the

1. Where a 4th wire is used on a 220v setup, that wire is simply a ground continuity thing for safety purposes.

Is all this correct? If so, I think I understand it now.

by code, you are to only connect the neutral to the ground electron point in the Breaker box and not at any other point. in 4 wire single phase, a forth wire (ground wire) is used many times to connect the appliance case at the end point, also you can legally have this ground reconnect to some other remote ground points but never reconnect the neutral to any ground other than what is in the breaker box where the main ground electrode comes in.

the same applies to equipment grounds where is you have a neutral wire (white) running around in the cabinet, only at one point will that neutral be connected to the cabinet ground using no smaller than a 10-32 stud how ever, multiple cabinet (case) grounds can be connected all over the place in side etc.. kind of strange i know but that is the way it is. i have seen in some cases in equipment panels where the neutral side of the 120 control source never see's a case ground.! oh well!

stuff

along

also

There are excellent articles on the web on MEN (multiple earth neutral) systems. It would be better for you too look at those first.

In North America it's 120-0-120 which comes from a center tapped transformer. The center tap is grounded and is also connected to the bare wire which connects to both the ground and neutral busses in the panel. From either hot to ground/neutral is 120v, between the two hots is 240v.

Better to call it a "current return" to avoid confusion with ground.

In the US, it ALWAYS is, or should be if the code is followed.

Redundant in the sense that the 2 are at the same voltage. The redundancy is for safety, however, so that the safety ground wire can never actually get a voltage on it.

Yes, as in # 3.

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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The Neutral is a current carrying conductor, for the 110 in this case. It is connected to ground in the entrance panel for safety to keep the hot wires from floating from ground.

Also the neutral is called a grounded conductor.

Ideally the neutral will never return any current to the ground because loads are ideally supposed to be balanced. Probably rarely achieved. If the unbalance is sufficient it can raise the ground connection about ground by several or more volts AC

And FWIW: The output of the transformer that feeds you house is usually two windings. Connected so they add to give 220. The two windings are interspaced with the primary for transformer efficiency among other reasons.

No one is mentioning a 4-wire system dealing with 3-phase power (Phase A,B,C + Neutral), where single-phase is available from a neutral connected from the WYE configured source (generator, transformers, utility) to any Phase or A to B; A to C; B to C. In countries outside of the U.S., with 220 VAC single-phase appliances, the system is a 380/220 volt 3-phase 4-wire system. You would have 380 volts single phase between any two phase wires, or 220 volts from any phase wire to the neutral. The U.S. equivalent is the 208/120v 3-phase 4-wire system for small-medium commercial use. Motors rated 208 vac 3-PH (i.e. air conditioners) could be used and lighting etc. on the 120 VAC from any leg to the neutral. The generator you mentioned most likely was a 3-Phase output.

Eh? Surely in an ideal installation the 'hot' wire will be at equal potential above both ground and neutral?

One exception (possibly more) is Norway, where they use 230V three phase, but one of the phase leads are at 0V potential. All the 230V "single phase" outlets are connected to two phases.

Norway uses 4 prongs in their three phase connectors, while the rest of Europe use 5 prongs, thre phases, neutral and ground.

Thomas

Eh? Surely in an ideal installation the 'hot' wire will be at equal potential above both ground and neutral?

Each one does. 60 times a second.

Bob AZ

You've still not explained what you meant. ;-)