# Delta transfomer being fed with neutral



## Tsmil (Jul 17, 2011)

Your toolie is a tool.


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## Vintage Sounds (Oct 23, 2009)

Whatever a toolie is that guy is talking out of his ass.


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## gilbequick (Oct 6, 2007)

What's a "toolie"?


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## Southeast Power (Jan 18, 2009)

bayareaelectric said:


> so here is the deal
> we have a jbox that has 3phases plus a neutral.
> out of the jbox we are feeding our delta transfomer. Since the xfrmr does not need a neutral on the primary. I wanted to abandon the neutral at the jbox , my toolie wants to pull it along with the other wires and land it at the x0 bar. If i leave the neutral at the box he says is going to hum and make noises . I do not know if he is correct to bring it and land it at the x0 due to the long run 200 ft of extra wire not needed ........ Anybody have similar situation before/??


Ok, now tell us what's going on on the load side of the transformer.


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## Safari (Jul 9, 2013)

jrannis said:


> Ok, now tell us what's going on on the load side of the transformer.


thats the same question I have for. the op

Sent from my HUAWEI Y210-0100 using Tapatalk 2


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## bostongtp (Apr 9, 2014)

Toolie is NOT a tool. This happend to me on a job. Retail shoe store about 10,000 sq ft. Got EVERYTHING done and at the end powered up the transformer, and for some reason it was humming very loud, the power analyzer crew performed some tests and suggested we install a nuetral, we just did as asked because we had no idea and it solved the problem. I don't know if it was harmonics, size or age of the transformer etc, but the transformer did hum very loud. when we installed the nuetral it went right away. Not like it got quieter,it went right away it was a night and day difference.

I know that doesn't help you AT ALL but I remembered this job, which was last June, that it happend on. And it gave the same symptoms as your description. Will this happen to you, unfortunately I'm not sure. I just know I encountered the scenario you described, sorry couldn't be more helpful.


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## Big John (May 23, 2010)

Boston, what did the neutral you installed attach to, exactly?


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## hardworkingstiff (Jan 22, 2007)

bostongtp said:


> I know that doesn't help you AT ALL but I remembered this job, which was last June, that it happend on. And it gave the same symptoms as your description. Will this happen to you, unfortunately I'm not sure. I just know I encountered the scenario you described, sorry couldn't be more helpful.


On the contrary, this is great help.

In addition to Big John's question, was your transformer a Delta/Wye?

By any chance did anyone put an ammeter on the neutral?


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## bostongtp (Apr 9, 2014)

The transformer went directly to a distribution board with 5 breakers I believe ( some 100a,200a, etc) which then fed Lighting panels, receptacle panels, etc.

The guys forgot to place overcurrent protection on the distribution board also, they fed the buss bars instead of feeding the 500 a breaker, I was told this was ok though because as long as the board has NO MORE than 5 breakers to throw you would be OK without overcurrent protection. I wouldn't recommend this but, it was an oops.

I wouldn't be able to tell you what the nuetral was carrying, the power guys were a seperate company testing the existing transformer, so when they said install a neutral/ground it to building steel we just started moving our feet no time for questions.

What made us question if there was an issue aside from the hum, was we were getting wierd voltage readings to ground, I think I was reading things like 168 from hot to ground on a 120/208v system. Also 1 guy said i wired an outlet wrong and blew up his hammerdrill. And again im not sure on the theory, I just know for fault conditions, on what I work with, its always a must to ground the xo ( or center tap). So yes the transformer was a step down delta/wye.


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## Big John (May 23, 2010)

Sounds like someone forgot to ground the neutral on the secondary.

What OP is talking about is grounding the primary delta. I don't know of any situation in <1000V wiring where you would ever ground a transformer primary.


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## bostongtp (Apr 9, 2014)

Also doesn't he need to hit an overcurrent device ahead of the transformer?

In the event of a fault on the primary how would the OCD operate to clear the fault?


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