Phase rotation inconsistency within site electrical system

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bmah

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Hello,

I am evaluating an industrial site electrical system (3-phase) that has undergone a few electrical updates over the last few years and ended up with some phase rotation inconsistencies, ie. the service entrance equipment is CCW phase rotation and half of the downstream distribution is CCW, but the other half is CW phase rotation (and actually switches back to CCW further downstream of the CW equipment...). It's a bit of a mess and my team is currently evaluating the process to correct the phase rotation issues for consistency.

One of the site electricians is adamant that the rotation be CW throughout since "most equipment is now designed for CW rotation", however I have found that the effort would be significantly greater to switch the CCW equipment (and end-use connections) to CW, rather than switch the CW equipment to CCW.
1. Is there an industry standard (or best practice) that specifies that the phase rotation should be consistent within an electrical system?
2. Is there an industry standard that recommends one rotation vs the other (CW vs. CCW)?
3. I am awaiting an opportunity for field verification, but I imagine that the phase conductor color-code is mismatched at the distribution equipment (SWGR, panelboards, etc.) wherever the phase rotation is switched. Would this be considered a violation of NEC 408.3(E)(1), since AC phase arrangement would be out of order at some panels?

Any input is appreciated. Thanks.
 
IMO all of the panels that are connected back to the same source should have the same configuration (i.e.- black-red-blue or brown-orange-yellow). When parts of the system get modified you can end up with the inconsistencies you've mentioned. As far as CW or CCW IMO whatever exists at the supply end (typically the service) should be consistent through out.

Welcome to the Forum. :)
 
I agree with infinity the color coding needs to be consistent. I prefer CW rotation as it makes phase monitors wiring simpler.
 
Thanks Infinity and Tom, I appreciate the input.

While phase rotation isn't specifically mentioned in the NEC, the more I think about this, the more I see it as a code violation of NEC 408.3(E)(1). Ex: a feeder breaker with feeder conductors a, b, c (left to right) switches to c, b, a (left to right) at the line-side main breaker of the downstream panel, reversing the phase rotation of the downstream panel. This results in "a", "b", "c" phases at the downstream panel are no longer left to right as required by 408.3(E)(1). So consistent phase rotation is actually a "shall" statement rather than an opinion or preference, Am I overthinking and/or stretching the meaning of this section....?
 
you say they are swapped at different places….
what does it matter? If your motor is running backwards you switch it there, correct?
also, are you positive you are landing the rotation leads properly?

Im with infinity on this one. Get the colors right. If the rotation is swapped your colors were marked wrong.
 
Hv&Lv said:
you say they are swapped at different places….
what does it matter? If your motor is running backwards you switch it there, correct?
also, are you positive you are landing the rotation leads properly?

Im with infinity on this one. Get the colors right. If the rotation is swapped your colors were marked wrong.
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Yeah I've gotten into some debates with people before who IMO over-emphasize the importance of rotation. In my experience there is no standard or consistency and you can't rely on equipment being one way or another so you're going to check it anyway when you hook something up. I have had two of the exact same RTU's be different internally.
 
electrofelon said:
In my experience there is no standard or consistency and you can't rely on equipment being one way or another so you're going to check it anyway when you hook something up. I have had two of the exact same RTU's be different internally.
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Same here, but bmah does bring up a good point. If the AØ-BØ-CØ on a panel in the basement is Blue-Red-Black can a panel on the roof be Black-Red-Blue?
 
infinity said:
Same here, but bmah does bring up a good point. If the AØ-BØ-CØ on a panel in the basement is Blue-Red-Black can a panel on the roof be Black-Red-Blue?
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That sounds extremely likely..
 
infinity said:
Same here, but bmah does bring up a good point. If the AØ-BØ-CØ on a panel in the basement is Blue-Red-Black can a panel on the roof be Black-Red-Blue?
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Not if there is more than one voltage system in the building. The conductors of each system must be identified as to both phase and voltage.
 
bmah said:
Thanks Infinity and Tom, I appreciate the input.

While phase rotation isn't specifically mentioned in the NEC, the more I think about this, the more I see it as a code violation of NEC 408.3(E)(1). Ex: a feeder breaker with feeder conductors a, b, c (left to right) switches to c, b, a (left to right) at the line-side main breaker of the downstream panel, reversing the phase rotation of the downstream panel. This results in "a", "b", "c" phases at the downstream panel are no longer left to right as required by 408.3(E)(1). So consistent phase rotation is actually a "shall" statement rather than an opinion or preference, Am I overthinking and/or stretching the meaning of this section....?
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I’d like to play devil’s advocate here and argue, “No.”

This is busbar labeling arrangement. It doesn’t direct you what wire has to be hooked up where, except for high leg arrangements. I agree that I wouldn’t swap back and forth, any more than I would run PVC or NM in a high end building.
 
Strathead said:
I’d like to play devil’s advocate here and argue, “No.”

This is busbar labeling arrangement. It doesn’t direct you what wire has to be hooked up where, except for high leg arrangements. I agree that I wouldn’t swap back and forth, any more than I would run PVC or NM in a high end building.
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Why would you not run PVC or NM in a "high end" building, if allowed? Isn't that a decision for the owner?
 
Yes it is, but given the choice, I would rather not work for an owner that prefers those methods, as it indicates to me a potential willingness to cheap out all around. (whether a fair prejudice or not.)
 
Strathead said:
Yes it is, but given the choice, I would rather not work for an owner that prefers those methods, as it indicates to me a potential willingness to cheap out all around. (whether a fair prejudice or not.)
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Have you looked at the prices of PVC compared to EMT lately?
 
Strathead said:
I’d like to play devil’s advocate here and argue, “No.”

This is busbar labeling arrangement. It doesn’t direct you what wire has to be hooked up where, except for high leg arrangements. I agree that I wouldn’t swap back and forth, any more than I would run PVC or NM in a high end building.
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I agree with the second sentence. I have seen many places where there is no conductor identification at the sup panels, and in all those cases it sort of didn't matter other than you can't determine rotation at a simple glance. If supplying loads where input rotation isn't an issue then it really doesn't matter at all or maybe say a panel filled with nothing but line to neutral loads.

Need more details before I would say no PVC or NM in a high end building. If a building with corrosive environment PVC certainly has some benefits that steel conduit has deficiencies with. But depending on just how "high end" you think it is maybe stainless is a better choice?
 
don_resqcapt19 said:
Not if there is more than one voltage system in the building. The conductors of each system must be identified as to both phase and voltage.
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But, black-red-blue, blue-red-black, blue-black-red are all the same voltage system colors, and unless the wire changes color inside a conduit, then one end is the same phase as the other end.
 
augie47 said:
Very few of the facilities of which I am aware were concerned about phase rotation on the distribution system.
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Everyone one I worked at was very concerned with having the same rotation through out the distribution system, even with multiple 5kv to .46kv transformers.
 
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