120/240 v single phase panel

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codequestion

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Can a 120/240v single phase panel be powered from 120/208v three phase panel with 120/208V three phase power? Does the code allow?

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kingpb

kingpb

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Yes, it is considered a 120/208Y; with that said, your 2pole loads must be capable of operation at 208V. If 240V is needed than as stated a transformer would be required.
 
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jap

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kingpb said:
Yes, it is considered a 120/208Y; with that said, your 2pole loads must be capable of operation at 208V. If 240V is needed than as stated a transformer would be required.
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I think he's wondering about the voltage rating issue with the 240v panel being fed off of a 2p breaker in the 3ph panel.

You actually do not have 120/208 Y at the subpanel if it's fed that way.

JAP>
 
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codequestion

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jap said:
I think he's wondering about the voltage rating issue with the 240v panel being fed off of a 2p breaker in the 3ph panel.

You actually do not have 120/208 Y at the subpanel if it's fed that way.

JAP>
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All is new work. Transformer secondary is 208v/120v feeding 208/120v panel three phase. Feeder breaker from 208v feeds 240/120 V panel. I think as mentioned by someone here earlier 240/120v panel can be used in 208/120v as long as there is no 240v loads.

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codequestion

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codequestion said:
All is new work. Transformer secondary is 208v/120v feeding 208/120v panel three phase. Feeder breaker from 208v feeds 240/120 V panel. I think as mentioned by someone here earlier 240/120v panel can be used in 208/120v as long as there is no 240v loads.

I just am not sure where in code it says that.





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Besoeker

Besoeker

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ActionDave said:
The panel is rated for up to 240V. You can feed it with 208V. This is done all the time. You can use two pole breakers also. There isn't very much in this world that is not usable at 208V.
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A 400V contactor coil?
They exist in this world......
:p
 
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GeorgeB

GeorgeB

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codequestion said:
Can a 120/240v single phase panel be powered from 120/208v three phase panel with 120/208V three phase power?
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You've gotten questions because of your question. A 120/240 panel can be fed with 120/208 3 wire (one is center of the wye) and EGC from a 3 phase panel ... from a 2 pole breaker. It cannot be fed with 3 phase conductors with or without the wye center.
 
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jap

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codequestion said:
Can a 120/240v single phase panel be powered from 120/208v three phase panel with 120/208V three phase power? Does the code allow?

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Click to expand...

But I will say your the king of confusing questions. :)

If your asking if a 1ph 120/240v panel can be fed 120/208v 1ph from a 120/208 3ph 4w Y Panel board by means of a 2p breaker in the 3ph panel, then, the answer is yes.

If that's not the question, then I'm still confused as to what the actual question is. :p

JAP>
 
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GoldDigger

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jap said:
Who cares that there's no 240v in the panel?

JAP>
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The OP might. He asked about feeding a 120/240 three wire single phase panel, he did not specify that there were only line to neutral loads on that panel.
A complete answer to his question would have to note that it could not drive 240V loads unless they were also rated for operation at 208V.
 
Besoeker

Besoeker

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jap said:
But I will say your the king of confusing questions. :)

If your asking if a 1ph 120/240v panel can be fed 120/208v 1ph from a 120/208 3ph 4w Y Panel board by means of a 2p breaker in the 3ph panel, then, the answer is yes.
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OK. Where would the 240V come from?
 
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codequestion

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GoldDigger said:
The OP might. He asked about feeding a 120/240 three wire single phase panel, he did not specify that there were only line to neutral loads on that panel.
A complete answer to his question would have to note that it could not drive 240V loads unless they were also rated for operation at 208V.
Click to expand...
Sorry for the confusion. To put it more clearly:

I have 480/277V transformer primary and 208/120V transformer secondary three phase. The transformer secondary feeds 208V/120V three phase panelboard.

The 208V/120V three phase panelboard has single phase 2 pole feeder circuit breaker which feeds to 240/120V single phase panelboard.

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GoldDigger

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codequestion said:
Sorry for the confusion. To put it more clearly:

I have 480/277V transformer primary and 208/120V transformer secondary three phase. The transformer secondary feeds 208V/120V three phase panelboard.

The 208V/120V three phase panelboard has single phase 2 pole feeder circuit breaker which feeds to 240/120V single phase panelboard.

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You have still not clarified what kind of loads will be fed from the 120/240 panelboard.
 
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