three breakers share one neutral and one grouding wires

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wrote:

The panel should be mark with it's type. You could post a picture of the nametag if you are unsure.
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On 23/11/2014 05:10, Seymore4Head wrote:

The panel has no writing of any sort. The electricians here don't even bother to label circuits for light, A/C, water heater, etc.
The panel and breaker are quite different from those used in the US. In the US, breakers get their power from the two bars in the middle of the panel. Here, you have to wire one breaker to the next. So, if the wire connecting breaker #5 and 6 is loose, breakers #6 and down will have no power.
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wrote:

You could still take a picture of the panel. If it is 3 phase, it should have 3 large connectors for three phase conductors. It should then have a large neutral bar for another large neutral conductor and another buss bar (maybe) for the grounds, depending on how old the panel is.
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On 23/11/2014 09:24, Seymore4Head wrote:

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On Friday, November 28, 2014 9:26:36 AM UTC-5, yyy378 wrote:

Maybe it's just me, but I find it a little weird that instead of just saying, this is in Katmandu, or wherever it is, you're expecting answers based on "it's not in the USA". Nor is there much other pertinent information. If safety is the issue, maybe you should ask the local inspection authority, assuming they have one in wherever it is.
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On 28/11/2014 21:25, trader_4 wrote:

thought I was asking a question in physics. Physics doesn't change from country to country. What is changed is code. I don't think my question is code related.
If I were in France, Britain, or Germany, I would have said so in the beginning because maybe somebody knows something there. But I am in Myanmar (and I have said so six days ago). Does it help anything? I doubt. There is no code in Myanmar. Once I asked the electric company which did a job for me to give me a conformity letter. They did not know what a conformity letter is. I then said I wanted a letter from them stating the work they did complied with government regulations. They said government did not regulate these things. If I had said in the very beginning I am in Myanmar, maybe people would think "Oh! I don't know anything about Myanmar" and just ignore my question.
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On Friday, November 28, 2014 6:20:14 PM UTC-5, yyy378 wrote: There are only two incoming cables. Cannot be 3 phase.

It does, because a quick google shows that you have single phase 230V or 3 phase. You've said you only have two conductors entering the building, so it sure sounds like you have single phase 230V service. You said you had several outlets installed on 3 breakers. Are these outlets all 230V?
And actually your question is code related, because you asked what is "safe". The safety standards are to a great extent, embodied in the codes and they vary from country to country. What is considered safe in one, may not be considered safe enough in another.
I

Let's assume you have 230V, single phase service. You said you have:
several new outlets on 3 breakers serving them are 3 hots, one neutral, one ground
You want to know if it's safe. First, we don't know for sure how it'w wired, so it's impossible to say for sure. But let's assume that one breaker is for each of the hots and that they all share one common neutral. That seems a reasonable assumption. Let;s also assume the grounds are done properly. That leaves two main aspects of safety that I see:
1 - Are the conductors and breakers sized and adequate for the max current? That would seem to mean the neutral would have to be larger than the hots.
2 - Since it sounds like it's almost certainly a shared neutral situation, then are the breakers sharing that neutral tied together so that they trip together? That's where you get to the finer points of safety. Here in the USA it's required to be wired that way for safety, so that someone working on it, won't make the mistake of having a neutral still carrying current when they have opened only one of the breakers that they think are associated with that neutral. Will it burn your house down? No. Is it allowed and considered safe in some other countries? Probably, especially if you have no codes.
I'd say if you're really concerned about the safety, then the only way you're going to know is get someone in there that's qualified to take a look.
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On 29/11/2014 18:18, trader_4 wrote:

that the electrician wires the single phase circuits in 3 phase way which is quite common here.
Not sure how to find a qualified electrician. Since the government doesn't regulate it, there is no license, hence, no licensed electrician.
Once I saw a plug of a piece of equipment being cut off and two leads are inserted into an outlet. I asked around to see who did it and was told an electrician did it. I was shocked. I'm no electrician but I know that is wrong.
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On Saturday, November 29, 2014 9:03:04 AM UTC-5, yyy378 wrote:

IDK how it would ever be possible to wire a single phase as 3 phase. Also, if you're knowledgable enough to know that, then I would think you could figure out what you actually have and how it's wired.
But for sure, to have single phase, 3 hots feeding outlets, only one netural, all same gauge, does not sound right as from what is given, the current on the neutral would be greater. The other possibility is the hots are over-sized, but that defeats the purpose of a shared neutral.

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On 11/29/2014 9:02 AM, yyy378 wrote:

I have seen an old farmer do that in the USA, but only to test and see if some thing worked.
He would then wire on a real plug, and do it more safely.
- . Christopher A. Young Learn about Jesus www.lds.org .
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...

This makes zero sense...there is no such thing as "wiring single-phase in a 3-phase way". It's either single or three phase.
Can you make a sketch of what this arrangement is or are you making assumptions as to what wires go where and where return neutrals/grounds may be just by looking at one end?
--





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On 11/28/2014 5:19 PM, yyy378 wrote: ...

The attached indicates Myanmar follows IEC and has 230V/50Hz distribution for low-voltage (household) use.
<http://www.legrand.com/files/fck/File/pdf/Guide-International.pdf Code in US isn't government-controlled, either, the NEC is written/maintained/underwritten by a private membership non-profit corporation. Local governmental regulations may require use of these Codes but that's not the same thing as the government itself actually being the regulator. Hence, I suspect the response to the question asked was correct; if you're located in a population center of any size I'd be quite surprised if there isn't a regulation somewhere that doesn't reference IEC or the like.
Now, that building codes and the like may not be enforced or very laxly enforced wouldn't surprise me a bit...there are areas in the US where that is also true.
As others have said, I suspect the only way to get any kind of resolution whatsoever on your queries here will be for you to take and post pictures on one of the hosting sites that show the subject pieces/parts and areas of concern/question. Simply trying to describe it with the unfamiliarity from both sides isn't going to get anywhere useful as can be seen from the meandering thread...
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wrote:

So if it's three phase it means that the neutral is never carrying more than one of the "returns" from any one of the three branches at the same time?
Even if that's true, isn't it still in some sense more heavily loaded then the three "hot" legs. Each hot leg is "hot" for one third of the time whereas the neutral is carrying "return" current ALL the time, at least if something is plugged in and running on each of the three legs.
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On Monday, November 24, 2014 3:36:45 PM UTC-5, Ashton Crusher wrote:

No. At least if my memory is correct, it's been a while since I worked in a plant with 3 phase power, but if the loads are balanced I think there is no return current at all in the "neutral." 3P is a way of doing 3 separate circuits that would normally need 6 wires (hot and return for each circuit ) with only 3 wires by taking advantage of the phase difference.
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Given that each of the hot legs is 120 degrees out of phase with respect to the others, the current in the grounded conductor (aka neutral) will sum to zero when all of the hot legs are pulling max current. In the worst case, where only one leg is pulling max current, the grounded conductor also conducts max current.
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On Mon, 24 Nov 2014 21:39:21 GMT, snipped-for-privacy@slp53.sl.home (Scott Lurndal) wrote:

Thanks Tim and Scott. Also saw some other similar explanations further down the thread. I assume there's only zero current when all the loads are the same inductively as well as resistively so there's equal phases shift on all legs??
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On Monday, November 24, 2014 8:58:41 PM UTC-5, Ashton Crusher wrote:

I'd have to go back to the text to answer that, probably someone else here is more current (pun) than I.
However, there's a complication. You can run 3P power without a neutral at all. 3 wires is enough to keep your equipment running, and any two of tho se three to run single phase equipment. But you have only phase to phase v oltage. For common US residential 3P, that means you would have only 208, from any hot leg to any other hot leg. To get 120 you run hot to neutral. It seems likely to me that this puts more current on the neutral. But as I said I'm rusty at this stuff. In the plant where I worked we had 440 fro m leg to leg to run motors, and 277 from leg to neutral to run lighting. W e had 3P in residential when I lived in Germany but I didn't work on it, it was a rental.
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On Tuesday, November 25, 2014 8:44:28 AM UTC-5, TimR wrote:

I don't see how that's a complication. It's the case that he's citing. If the load or loads are balanced, on all 3 phases, then you have no curren t in the neutral.

e. For common US residential 3P, that means you would have only 208, from any hot leg to any other hot leg. To get 120 you run hot to neutral. It s eems likely to >me that this puts more current on the neutral.
If it were balanced to begin with and you placed an additional load from one phase to neutral, then the load through that load would flow through the neutral. If you put two more identical loads on the other two phases, then the overall load would be balanced again and there would be no load through the neutral again.
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On Wednesday, November 26, 2014 9:19:01 AM UTC-5, trader_4 wrote:

age. For common US residential 3P, that means you would have only 208, fro m any hot leg to any other hot leg. To get 120 you run hot to neutral. It seems likely to >me that this puts more current on the neutral.

I'm not sure I'm following you.
I have L1, L2, L3, and N.
I can put a load between L1 and L2, L1 and L3, and/or L2 and L3, at 208 V ( thinking residential). No current should flow through the neutral. Even if the loads are unbalanced, maybe.
I can put a load between L1 and N at 120 V. That full load current will fl ow through the neutral.
Now add a load between L1 and L2. Will that reduce the load through the ne utral? Doesn't seem like it should. Adding a load betwen L2 and N might?
I'm pretty sure I had to solve problems like that in the basic circuits cou rse. Trouble is that was way back in the 80s and I disremember.
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On Wednesday, November 26, 2014 10:49:42 AM UTC-5, TimR wrote:

ltage. For common US residential 3P, that means you would have only 208, f rom any hot leg to any other hot leg. To get 120 you run hot to neutral. It seems likely to >me that this puts more current on the neutral.

if the loads are unbalanced, maybe.

Put additional equal loads between L2 and N and L3 and N. The current in the neutral is now zero.

You're right, it won't reduce the current through the neutral because the current has only one place to go, there is nothing else connected to the neutral.
Adding a load betwen L2 and N might?

Yes, per the example given.

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