240 volt 3 phase 3 wire service

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aelectricalman

aelectricalman

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When businesses with three phase 240V equipment are located in areas where three phase service is not available, Louisville Gas and Electric tells me I must do the following. They stated this is called a 3 phase 3 wire 240v service and this is what they are trying to get me to believe I should do. I've never done this and quite frankly I cant see how it possibly works. They stated that I bring 3 wires into the panel where Phase A and C are the 240V and a neutral. B phase is not connected to an ungrounded leg from the xfmr however the B lug is jumpered to the equipment ground. Now, my question is, what is this about? I've just never seem this I really dont know how to go about breakering this type of service. Have anyone ever seen this in the field and if so how does it work as three phase? It sounds to me like a 240/120V single phase just fancied up.
 
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So then why does B phase have overcurrent protection.

So then why does B phase have overcurrent protection.

Roger, sorry about the language. I guess my idea of editing was still vulger. The f actually meant farad. :)

I guess where Im stumped is, why is B breakered? Just not used to it I guess.
 
aelectricalman said:
When businesses with three phase 240V equipment are located in areas where three phase service is not available, Louisville Gas and Electric tells me I must do the following. They stated this is called a 3 phase 3 wire 240v service and this is what they are trying to get me to believe I should do. I've never done this and quite frankly I cant see how it possibly works. They stated that I bring 3 wires into the panel where Phase A and C are the 240V and a neutral. B phase is not connected to an ungrounded leg from the xfmr however the B lug is jumpered to the equipment ground. Now, my question is, what is this about? I've just never seem this I really dont know how to go about breakering this type of service. Have anyone ever seen this in the field and if so how does it work as three phase? It sounds to me like a 240/120V single phase just fancied up.
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This does not sound right????

You may be misunderstanding what was directed to you or the person from the POCO was misrepresenting what was supposed to be said.

I would ask for a detail from the POCO... most POCOs have a book with these available.
 
A more normal approach would be to use a single phase panel, and use the two "hots" along with a "neutral" to serve the 3-phase loads. They're just showing you another option by using a 3-phase panel and jumping the "neutral" to the b-phase. I don't really like that method.
 
aelectricalman said:
So then this requires a single phase 400 amp meter.
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I sorta doubt it, but I can't honestly say how they meter corner grounded delta. I've never put one in from scratch. Just worked in a few places that were so served.
 
So basically I skip 2, 5, 8,11,14....................... when using this setup. 1/3 of my panel is dead in the water. My 240v overcurrent protection should be 2 pole.
 
Is this a 3 phase system or isn't it? Your first two sentence contradict each other:

three phase 240V equipment are located in areas where three phase service is not available
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They stated this is called a 3 phase 3 wire 240v service
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Im not sure your motives behind that question?

Are you trying to help me solve my dilemma?

If you would have read the question, it stated that is what I was told from LGE. If you havent figured out where Im going with this thread, please forgive me, Im actually trying to figure out if this thing is a true 3 phase service, or some horse crap LGE is doing because they are too cheap to do it right. Thanks for help.
 
That's a 3 Phase 3 wire only service, with center phase grounded... This system works without a Neutral. It's strickly used for 3 Phase/3 Wire equipment...
 
I think Marc is right

I think Marc is right

aelectricalman said:
When businesses with three phase 240V equipment are located in areas where three phase service is not available, Louisville Gas and Electric tells me I must do the following. They stated this is called a 3 phase 3 wire 240v service and this is what they are trying to get me to believe I should do. I've never done this and quite frankly I cant see how it possibly works. They stated that I bring 3 wires into the panel where Phase A and C are the 240V and a neutral. B phase is not connected to an ungrounded leg from the xfmr however the B lug is jumpered to the equipment ground. Now, my question is, what is this about? I've just never seem this I really dont know how to go about breakering this type of service. Have anyone ever seen this in the field and if so how does it work as three phase? It sounds to me like a 240/120V single phase just fancied up.
Click to expand...
I think they are selling you a 240v corner grounded delta and you will need a transformer to get 120/208 or 120 /240 power.
 
aelectricalman said:
Im not sure your motives behind that question?

Are you trying to help me solve my dilemma?
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Sorry for the direct tone, but we're all trying to understand what you have to properly answer the questions. Without the proper information we're all just guessing which will not help you to find an answer. Your OP said that a "three phase system is not available". To me that means that you do not have a three phase service, but you also said that the POCO is calling this a 3 phase 3 wire service. One of those statements is false. By figuring out which one it is will allow someone to properly answer the questions.
 
Chris
I am not sure if I missed the link for the schematic...but I still think that from the way you have described this installation, the method the POCO wants you to tie into the panel is not correct.
3 phase corner grounded, although not common are still around. I am assuming this is a building with motor loads.

Remember the grounded phase leg is required to be identified with white or gray tape.
I have some drawings in my files somewhere, I will try to find them later today- you know sort of like a Pre-SuperBowl thing. ;)
 
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