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Discussion Starter · #1 ·
We have a job going (different foremen) that I had to go to today for a change over from overhead to underground feed. Real easy. We put this gear section up and nippled through to the main. Few pics. Nothing special.
 

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Discussion Starter · #4 ·
SteveBayshore said:
I haven't seen a metering set up with CTs like that before. Is it common to have two phases looped through one CT? Any reasonng for it? Did the POCO require the customer to pay for the pad mount upgrade?
Not sure about the ct's. But what was unusual was that it was a 120/240 three phase.
The customer is building a 20million dollar building and redoing three huge parking lots. All the overhead is going under and we put all new LED light poles. This is their existing. administration building on the same property. So in sure their paying Edison.
 

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OK, I understand the metering now. Our old 240 delta services don't have the high leg metered at all. Didn't know it was delta from the phase colors. NEC requires ORANGE marking on the high leg. NEC also requires high leg on center buss unless required different by POCO.
 

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Bilge Rat
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On a 4 wire ∆ system, it's common to have the two 120 volt leg going opposite directions through one CT. The CT will measure all current in both the legs at the same time. (The currents will add to each other) A single phase CT system can have one CT and both legs going in opposite directions as well.

The high leg must be measured separately because its voltage to neutral/ground is different than the other two.

Every POCO I've worked with requires the high leg to be C. It is normally changed to B between the CT can (or meter base) and the panel.

I usually go C-A-B in the POCO equipment, then A-B-C in the panel. This sounds strange, but it is the only way to have the high leg C at POCO and B at panel and have the same phase rotation throughout the entire system.

The high leg should be orange, but it is not exactly required to be. 110.15 states, in part, "marked by an outer finish that is orange in color or other effective means." I'm not sure if blue would be considered 'effective means' or not.

P.S. A dead giveaway that a service is a 4 wire ∆ is that one of the pole-mount transformers is larger than the other two.

P.P.S. Is the wire coming up from underground the POCOs? Most likely, since they used red-blue-white as the phase conductors.
 

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Discussion Starter · #8 ·
There was no high leg. I know strange and far beyond my knowledge. My pm the Edison crew leader and myself had a 15 minute conversation on the special transformer they had to get.
 

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OK, I understand the metering now. Our old 240 delta services don't have the high leg metered at all. Didn't know it was delta from the phase colors. NEC requires ORANGE marking on the high leg. NEC also requires high leg on center buss unless required different by POCO.
If the plant is a 3 phase delta service with no neutral, is the high leg still required to be orange ? Working at one now with no marking.
 

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Not sure about the ct's. But what was unusual was that it was a 120/240 three phase.
The customer is building a 20million dollar building and redoing three huge parking lots. All the overhead is going under and we put all new LED light poles. This is their existing. administration building on the same property. So in sure their paying Edison.

Isnt literally every other service in California 120/240 high leg?
 

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Bilge Rat
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There was no high leg. I know strange and far beyond my knowledge. My pm the Edison crew leader and myself had a 15 minute conversation on the special transformer they had to get.
If there is a neutral and 3 phases and two of them are going opposite directions in one CT, and one phase has its own CT, it's a ∆ with a high leg. The POCO guy doesn't know the ∆ system very well; he's thinking it's a wye with something wrong with one of the phases.
 

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Discussion Starter · #18 ·
micromind said:
If there is a neutral and 3 phases and two of them are going opposite directions in one CT, and one phase has its own CT, it's a ∆ with a high leg. The POCO guy doesn't know the ∆ system very well; he's thinking it's a wye with something wrong with one of the phases.
We'll due to unforeseen circumstances I'm back at the job. What exactly can do to prove to you what I'am saying is true?
 

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Bilge Rat
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If the plant is a 3 phase delta service with no neutral, is the high leg still required to be orange ? Working at one now with no marking.
Most likely the grounded phase would need to be white or gray because it is a current-carrying conductor that is intentionally grounded.

This would be very confusing though; it'd look a lot like single phase but there's no 120 available. 240 phase to phase and 240 phase to neutral/ground.

The few I've seen were red or orange.
 

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Discussion Starter · #20 ·
micromind said:
If there is a neutral and 3 phases and two of them are going opposite directions in one CT, and one phase has its own CT, it's a ∆ with a high leg. The POCO guy doesn't know the ∆ system very well; he's thinking it's a wye with something wrong with one of the phases.
Again he says this is a special order transformer. No one on his crew has ever seen this set up before.
 
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