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jack b
Gone Fishing
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join:2000-09-08
Cape Cod
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reply to sk1939

Re: Poco infrastructure question

This style meter is commonly used when supplying 2 phase service to a customer from a standard 3 phase 120/208V distribution system.
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ArgMeMatey

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said by jack b:

This style meter is commonly used when supplying 2 phase service to a customer from a standard 3 phase 120/208V distribution system.

So phase-to-ground would be 120V and phase-to-phase would still be 208V, wouldn't it?

I was thinking it might be the "house" meter, for common area lighting, maybe a fire alarm system and other small loads on a minimum-cost service that would never need 208 or 240V circuits.
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jack b
Gone Fishing
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Cape Cod
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Yup, 120 V to neutral, 208 V to phase. The meter is rated for 200 amps, the load could be anything up to that.



whizkid3
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join:2002-02-21
Queens, NY
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reply to ArgMeMatey

said by ArgMeMatey:

said by jack b:

This style meter is commonly used when supplying 2 phase service to a customer from a standard 3 phase 120/208V distribution system.

So phase-to-ground would be 120V and phase-to-phase would still be 208V, wouldn't it?

Exactly what we have throughout NYC, and likewise throughout many other cities. Its single-phase 208/120V power, not 'two-phase'.


ArgMeMatey

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said by whizkid3:

Its single-phase 208/120V power, not 'two-phase'.

Thank you. I was wondering how you'd measure 2 phases on a 120V meter. Getting confused with 240V grounded B phase.


John Galt
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said by ArgMeMatey:

said by whizkid3:

Its single-phase 208/120V power, not 'two-phase'.

Thank you. I was wondering how you'd measure 2 phases on a 120V meter. Getting confused with 240V grounded B phase.

Is that delta...??

Or are you referring to a "high leg" system?


ArgMeMatey

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said by John Galt:

Is that delta...??

Or are you referring to a "high leg" system?

aka Corner-Grounded Delta. I just looked that up because I'm no expert. One transformer with three secondary taps. One tap (B) grounded. So A & C are 240V to ground.

Advantages:
- cheaper 2-pole gear can be used all down the line
- there are only three conductors just like split phase 240V
- B phase does not have to be (and CANNOT be) switched or fused.

But this is not what the OP has.

Also I ran across something on Wikipedia that mentioned that the old power station at Niagara Falls was two-phase. Maybe that was where I'd heard that before.
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whizkid3
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Queens, NY
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4-wire, 3-phase 208/120 from a wye secondary on a transformer. Tie into any two phase conductors and the neutral, and you have single-phase 120/208. (Regardless of what they were doing in Niagara Falls ages ago.)