three breakers share one neutral and one grouding wires

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What part of "this is not in the U.S." did you find confusing? And who said it's in a residence? Certainly not the OP.
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wrote:

AIUI, grounds are grounds are grounds.
But neutral wires are conductors of electricity, the same amount that the hot wires carry.
Did he only use ONE neutral wire for all the outlets powered by three different breakers? So for example, the breakers will provide 15 amps each, 45 amps total, and the only neutral wire has to return up to 45 amps!!!! You can't carry 45 amps on 14 gauge or even 12 gauge wire, so no, it's not right.

What about the FEC, the Foreign Electrical Code?
AFAIK, the NEC is based on reality, and doesn't disapprove of things that aren't unsafe, at least somewhat**. Maybe that's not always true, but anything it says about this sort of thing probably does relate to safety.
**Small risks that people would take, or that they didnt' even know about , 50 years ago aren't permitted anymore, but why should non-Americans bear these risks when they are known now?
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On Wednesday, November 19, 2014 5:54:03 PM UTC-5, micky wrote:

When there is more than one hot and they are not the same phase, a neutral doesn't have to carry the same current that the hots carry. That's how an Edison circuit, otherwise known as a shared neutral works. You see that used here, even in residential applications.

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On Wed, 19 Nov 2014 20:26:15 +0000 (UTC), Doug Miller

I didn't think of that. But if it were a 3-phase circuit, could one wire accurately be called "neutral"?
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micky presented the following explanation :

electricy.
The OP said 5 wires which is exactly the way Electricity is distributed in Europe Australia and many other countries. 15 amps in each phase seperated by 120 degrees results in NO NIL NOTHING in the neautral wire.
Admitadly not all domestics get 3 phase, I have 3 phase because I hava a split system Air con and so do many of my neighbours. My previous house did not have A/C until very late and then the supply was changed to 3 phase.

The NEC is based on the archaeic Edison system and so is not the Bible for more advanced systems. :-Z
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On 11/19/2014 05:18 PM, John G wrote:

<snip>
I worked with it industrially for 38 years few of us here (myself included) made the assumption that the residence was three phase...though as pointed out...it could be.
The OP did not give enough info for anyone here to know.
Now, if it is a three phase "wye" feed and there are a total of three , single phase outlets the neutral current would not be zero unless the loads at all three outlets were the same...however...if it is three phase, then the electrician probably did wire it correctly.
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ground, neutral, and one for each of the three phases. Phase-to-phase voltage is 208V, and phase-to-neutral is 120V, in a typical North American installation.
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Maybe you should stick to subjects you know more about. If this is 3-phase wye, there's absolutely nothing wrong.
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email.me:

Note that you're also making the assumption that it's even a residence. The OP never stated that.
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It happens that philo  formulated :

You are correct, the neutral current will only be zero when all three phase loads are equall but the neutral current will never be more than the total on ONE phase when the other 2 phases have no current. Hence the wires would be quite acceptable if all were the same size.
It would be nice if the facts were quoted instead of blind assertions from limted sources such as Worldstandards" "three-phase electricity is rarely used for domestic purposes"
In fact 3 phase is very common outside the USA
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On 11/19/2014 06:49 PM, John G wrote:

Three phase is very common in the US, just not in residential
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I also worked around lots of 3 phase of several differant voltages in industry. I did not make any asumptions when the OP said not in the US. I don't know very much about other countries. We did get in some odd ball (for the US ) 380 volt 3 phase equipment on a project about 25 years ago. No one told us and we were trying to adjust some 3 phase 300 amp heaters to 480 volts out. Most we cold get was 380 volts. Decided to check the incomming power and the transfrormers were set for 380 that the equipment needed.
Damn junk from other countries are going to get people over here killed. Seems that in the large 3 phase cabinets the disconnect is colored backwards from the old US. If the pointer is on Green, that means the power is off and it is safe to go in. If Red it means the power is on and it is not safe. We were used to seeing it the opposit, Red is off and green is when the power is on.
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On 11/19/2014 06:56 PM, Ralph Mowery wrote:

Wow
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Let; not start talking about triplin harmonics. Heads would explode.
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On 11/19/2014 11:31 PM, snipped-for-privacy@aol.com wrote:

It's not that complicated. In a three phase "wye" the center tap (even with unbalanced loads) would not draw any more current than that of the most used leg.
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philo wrote:

I seem to recall Switzerland was one of the countries that used residential three phase power.
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On 11/20/2014 09:54 AM, Pete C. wrote:

From what I've found on-line I guess three phase is fairly common for residential in Northern and Central Europe.
Due to higher energy costs, Europe has been more energy conscious that the US.
The company I worked for (Enersys) manufactured industrial batteries and chargers. Some years back they bought out a French manufacturer of high-frequency conversion battery chargers which were more efficient that those being produced by the old Hertner plant in Cleveland. The Cleveland plant now builds the chargers used in the US...so it has all worked out well.
Three phase 460v would be rectified then converted to hi-frequency AC before it was sent to the transformer to reduce the voltage and increase the current.
In a standard battery charger the main transformer could be as much as 350#. The high-frequency transformers can be held in your hand!
The old chargers (both SCR or Ferroresonant) are still being made as their efficiency can be as high as 80%. The hi-freq chargers can get closer to 95% efficiency and had been made in Europe for 20 years before they started getting popular here.
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That is where harmonics come in. The triplin harmonic would lag the voltage to the point where it would show up in the current of an adjacent leg For this reason, they sell "super neutral" cable with the neutral 2 wire sizes bigger than the ungrounded conductors. This happens where you have a large component of electronic ballasts and switching power supplies. http://www.afcweb.com/mc-metal-clad-cables/super-neutral-cable-neutral-per-phase-or-oversized-neutral/
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On 11/20/2014 11:25 AM, snipped-for-privacy@aol.com wrote:

yes, that's true,
I guess I was thinking of just a resistive load
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They are getting more rare every day.
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