Phase Rotation

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merriar

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It seems customary for the power company to land their delta high-leg conductor on "C" phase on the line side of the service. Section 408.3(E) tells us to terminate the wire on "B" phase in our service panel. Isn't it customary for the power company to give us A-B-C phase rotation? When we switch the wires we are changing that rotation. Don't we want to be maintaining A-B-C rotation in our installations?
 
Meter bases are set up for the high leg on C for proper metering. Then we take it to B. If you need to change rotation, swap A and C down stream.
 
The Meter is not required by code. Follow any POCO requirements and just roll the conductors to maintain the correct phase rotation and arrangement
 
As Tom said, just roll the connections.

POCO gives you A-B-C, where C is the high leg, then roll them to B(as A)-C(as B)-A(as C). This maintains POCO rotation.
 
The poco doesn't really care what rotation they give you, they try to keep everything on their side consistant, as rotation does not matter with their metering, but in order for their meter to work correctly, the high leg is always on "C" phase in the meter base. I have found that Duke power is almost always CCW rotation, at least in North Carolina. I have replaced service laterals that were damaged by a pad mount transformer being hit by vehicle, and when Georgia Power hooked it back up, they could not guarantee the rotation was the same, although we phased everything back the same. (They have inadvertently changed it on several occasions.)
 
Yep, same as above. ACB through the meter base to ABC at the service disconnect. I do this everytime, no matter what, because sometimes I'm not sure what service voltage I'm getting.
 
merriar said:
It seems customary for the power company to land their delta high-leg conductor on "C" phase on the line side of the service. Section 408.3(E) tells us to terminate the wire on "B" phase in our service panel. Isn't it customary for the power company to give us A-B-C phase rotation? When we switch the wires we are changing that rotation. Don't we want to be maintaining A-B-C rotation in our installations?
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That is IF it were CW in the first place? (If it were an existing service you're replacing...)


Back when I was a schmuck... (Early 90's) I was helping out - by failing to mark the service drop before I cut it... Lots of grief from all on hand.... (Including those who were supposed to be in charge....) Long story short - we all waited while someone ran and got a rotation meter - hooked back up CW - went to go find motors to check in the building - ones that wouldn't damage anything..... In the meantime some dope being paid more than I at the time - got on the frieght elevator in lapse of reason - broke it. Up=Down Down=Up (not too bad - but went past a limit switch)

Back to CCW as it was before....
 
e57 said:
went to go find motors to check in the building - ones that wouldn't damage anything.....
Click to expand...


Something I ran in to on checking motor rotation last summer. A storm dropped a tree and wiped out the POCO lines feeding one of our sewer plants. I told a fellow electrician to go check the rotation on a few motors in a building that we knew the rotation wouldn't kill stuff. He came back out and said everything was cool, right rotation.

I didn't know he only checked one motor. It was on a VFD! VFD's, at least everyone I have ran in to, don't care about rotation. Flipped the breakers for the rest of the buildings.

Five years ago we asked for the money to install phase monitors on all of the motors and they told us the plant will be off line in a year, "we don't need to spend the money." Five one years....

Several thousand $'s of damage. Two days of repair and installing phase monitors on every motor in the plant........
 
hockeyoligist2 said:
Something I ran in to on checking motor rotation last summer. A storm dropped a tree and wiped out the POCO lines feeding one of our sewer plants. I told a fellow electrician to go check the rotation on a few motors in a building that we knew the rotation wouldn't kill stuff. He came back out and said everything was cool, right rotation.

I didn't know he only checked one motor. It was on a VFD! VFD's, at least everyone I have ran in to, don't care about rotation. Flipped the breakers for the rest of the buildings.

Five years ago we asked for the money to install phase monitors on all of the motors and they told us the plant will be off line in a year, "we don't need to spend the money." Five one years....

Several thousand $'s of damage. Two days of repair and installing phase monitors on every motor in the plant........
Click to expand...




I had a well seasoned veteran electrician try and tell me that when wiring the plant (any production plant) from scratch when wiring all your motors, if you wire your motors B1, O2, Y3, then the motor would automatically be turning the right way.:roll: He said it didn't used to be like that,,,,,the power company's getting better and better about it. :roll:

I told him he was off his rocker
 
That one thing my SOP is bring the phase roation tester with moi so you can able verify if that is on CW or CCW rotation.

I have that issue all the time in France so it become a automatic thing you have to bring out the rotation tester I never really trust the conductor colour even the numbers :roll:.,,,

But once you verify it either you leave it as it is or roll the whole bloody thing one rotation then you are good to go.

Merci,Marc
 
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