3 phase delta sub panel

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Really, I am not trying to be pedantic. Preventing misunderstandings is one reason there are IEEE/ANSI standard methods for describing voltage systems.
 
jim dungar said:
Really, I am not trying to be pedantic. Preventing misunderstandings is one reason there are IEEE/ANSI standard methods for describing voltage systems.
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If it makes you feel any better it was you that got me thinking about how I post voltages. :cool:

I never knew there where standard ways of posting voltages until you brought it up.
 
The 240/120 3PH 4W delta system produces a nominal 208V to ground/neutral conductor from the high leg. To call it anything else adds confusion and misinformation as well as violates the NEC
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Whatever dude. It won't be my first or my worst violation. I don't know what nominal means and I have no desire to look it up. If I am doing something dangerous, let me know and I'll change my ways.

All I care about is that some knucklehead doesn't hook up a 120 circuit to the high leg.
 
acrwc10 said:
I am feel the imbalance caused by using only 2 of the 3 phases is a big issue with this installation if they do not correct the system to a 120/208 Y.
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208Y/120 is not more 'correct;' they're different systems. The 4-wire high-leg services I've seen almost always have a larger 120/240v 'main' transformer and a smaller high-leg unit for the 3-ph loads.There's no 'imbalance' for a system designed for the loads.
 
iwire said:
I never knew there where standard ways of posting voltages until you brought it up.
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Really? There have been several higher-voltage-first-for-3ph/lower-voltage-first-for-1ph discussions here about how to describe the supply. I'm suprised you haven't noticed (or remembered.)
 
220/221 said:
I don't know what nominal means and I have no desire to look it up.
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Translation: It is my God given right to shut the door on education and remain ignorant, I dare someone try to point me in the right direction. :D

Roger
 
roger said:
Translation: It is my God given right to shut the door on education and remain ignorant, I dare someone try to point me in the right direction. :D
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Additional translation: Don't confuse the issue with facts.
 
LarryFine said:
208Y/120 is not more 'correct;' they're different systems. The 4-wire high-leg services I've seen almost always have a larger 120/240v 'main' transformer and a smaller high-leg unit for the 3-ph loads.There's no 'imbalance' for a system designed for the loads.
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Not on the last one I worked on, all three transformers were the same size. Maybe this is because it was a converted machine shop.It was also not a service it was a feeder on a separately derived system. I don't want to imply I know more then you on this subject, I have just been taught the imbalance would be an issue. I feel if this is an IT room that is go to need room for expansion to leave it with a "high leg" would be poor planning. It is much easier to change it now rather then later.
 
Translation: It is my God given right to shut the door on education and remain ignorant,
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A) I don't need you to translate for me.

B) I am far from ignorant.

C) Half of the reason I am here is to be educated. The other half is to help educate others.


I don't know what nominal means = I don't know what nominal means.

I have no desire to look it up = I have no desire to look it up.

Don't complicate things.
 
220/221 said:
I don't know what nominal means = I don't know what nominal means.

I have no desire to look it up = I have no desire to look it up.
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Which pretty much proves Roger's point. :grin:
 
What if you had a 120/208v system and needed to add a subpanel out of a main panel. The only things needed to be ran off the subpanel were single pole loads like lights, receptacles, and baseboard heat would it be better to just a single phase panel, or would you have to add the three pase panel to balance between the three phases?
 
codeunderstanding said:
What if you had a 120/208v system and needed to add a subpanel out of a main panel. The only things needed to be ran off the subpanel were single pole loads like lights, receptacles, and baseboard heat would it be better to just a single phase panel, or would you have to add the three pase panel to balance between the three phases?
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Just my opinion, it would be irresponsible to put in a single phase load center if you had a 3 phase service, unless it was a residential setting.
 
acrwc10 said:
Just my opinion, it would be irresponsible to put in a single phase load center if you had a 3 phase service, unless it was a residential setting.
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Thats true. But wouldnt that make the system unbalanced if you did. If you put the feeder on a and b phase that make c phase onthe system all out of wack right?
 
codeunderstanding said:
. . . wouldn't that make the system unbalanced if you did. . .
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It depends on how the system was loaded and how much load you intend to put on the 120/208 volt single phase panelboard. We permit 100 ampere commercial services on 208Y/120 volt transformers but our smallest transformer is 75 kVA (normally larger) and the demand would only be 40 amperes maximum (our demand factors, not from Article 220). If you put a small load on the two lightest loaded phases, I don't see a problem. :smile:
 
Which pretty much proves Roger's point.
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Translate this, pal.

would it be better to just a single phase panel, or would you have to add the three pase panel to balance between the three phases?
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Logic tells you to use all three phases in a 120/208 system.

Logic tells you to use a single phase panel in a 120/240 delta system.
 
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