Three-phase and single-phase 208V conductor color-coding practices.

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Jon456

Jon456

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Colorado
I know that the NEC does not dictate insulation color choices for phase conductors. But I'd like to get recommendations and industry best-practices from the esteemed members of this forum. I've worked with 3-phase before, but it's always been in the setting of big industrial applications (field pump motors, solar installation, transformers, etc.) with large conductors and where the phase orientation is critical. But now I'm working with some small branch circuits in a commercial building with 208Y/120V service.

A couple of the loads are 3-phase 208V (a fan and a VFD driven motor). Several of the loads are 1-phase 208V. The rest are 1-phase 120V.

I'll be pulling as many as 9 current-carrying conductors through 3/4" EMT, and I'm trying to decide on the best way to distinguish the different circuits, particularly the 208V circuits.

For example, I could use black/red/blue for a 3-phase 208V load. Or I could use all blue and tape the ends to indicate the A-B-C phases. I'm leaning towards the latter because it reduces the duplication of color with the other circuits in the conduit, making it more obvious which circuit is which.

For the 1-phase 208V loads, I could use something like black/red or I could use something like orange/orange. Again, the latter would make it easier to distinguish each branch from the others in the conduit. And since these are dedicated circuits, the phases are irrelevant. But it would probably be prudent to mark the phases so someone doesn't think they are the same phase.

Finally, I have one 120V MWBC feeding a couple of receptacles. In this case, I think it would be imperative to use two different colors to distinguish the phases so that if someone else were to work on the circuit, they would know that the two wires are not coming off the same phase. Two conductors of the same color could be used with tape marking the phases, but if a taped end were ever cut off, it could result in someone creating a hazardous situation.

Thoughts?
 
Is the motor VFD circuit wiring after the VFD? If so you sure wouldn't want that getting crossed with another conductor. Also, I don't know that I would want VFD output conductors in a raceway with other circuit conductors.

As far as coloring, I would use normal blk/red/blu | A/B/C for everything and bundle the phases together everywhere theyre exposed, and label them where appropriate.
 
Todd0x1 said:
Is the motor VFD circuit wiring after the VFD? If so you sure wouldn't want that getting crossed with another conductor. Also, I don't know that I would want VFD output conductors in a raceway with other circuit conductors.

As far as coloring, I would use normal blk/red/blu | A/B/C for everything and bundle the phases together everywhere theyre exposed, and label them where appropriate.
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I meant bundle the phases of each circuit together.
 
Todd0x1 said:
As far as coloring, I would use normal blk/red/blu | A/B/C for everything and bundle the phases together everywhere theyre exposed, and label them where appropriate.
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I'd add use different colored tape for each black/red/blue/white bundle, and other combinations.
 
Todd0x1 said:
As far as coloring, I would use normal blk/red/blu | A/B/C for everything and bundle the phases together everywhere theyre exposed, and label them where appropriate.
Click to expand...
There are only two 3-phase circuits, and they are in different conduits going to different locations in the facility. So there's no chance of them getting mixed up. But there are other single-phase branch circuits in each of those conduits.
 
Jon456 said:
There are only two 3-phase circuits, and they are in different conduits going to different locations in the facility. So there's no chance of them getting mixed up. But there are other single-phase branch circuits in each of those conduits.
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Are the single phase circuits really single (all the same) phase or are they 2 or two phase conductors from the three phase? That will determine what colors you should use for the single phase circuits.

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I would just use black-red-blue for the 3Ø loads and white with whatever the appropriate phase color is for the 120 volt loads. With 9 conductors it shouldn't be very difficult to identify which conductors go together. I would just separate them with wraps of tape and individually number them when it's all done.
 
GoldDigger said:
Are the single phase circuits really single (all the same) phase or are they 2 or two phase conductors from the three phase? That will determine what colors you should use for the single phase circuits.
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The single-phase 120V circuits draw selectively from A, B, or C for panel balancing.
The (qty 3) single-phase 208V circuits are A-B, C-A, and B-C, again for balancing purposes.
The one single-phase 120V MWBC draws from A-B.

I was thinking it would be better to minimize a lot a lot of color duplication in each conduit so it's more clear which circuit is which. I do group and label my circuits, but it's still nice to have a more visual distinction between the conductors. I've found that most installs are not grouped or labeled at all and it's always a PITA trying to sort out the circuits when you have several black and several red in the same junction box.
 
Only NEC requirement is to identify each voltage system and phase when there is more than one voltage system on the premises. If this is a facility with only one voltage system (description so far seems to be this is the case) there is no requirement to identify things like described, but still maybe a good design choice.
 
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