NEC 400.5 AND 3 PHASE PLUGS

[fifty60]

I am using NEC 400.5 to size power chords. My understanding of 400.5 is this: 3 current carying conductors in a jacket use column A. 2 current carrying conductors in a jacket use column B. I know there has to be more to it than that. Is there anything else with 400.5 that I should consider when sizing SOOW cable to be used for powerchords?

I am using the chord for use with switch rated plugs. My final question is this: the customer has a 460V 3phase supply. My machine operates on 2 phases of the 460V 3Phase. I only need to have a plug with 2 conductors and a ground that is rated for 460V? There is no reason to buy the full 460V 3 Phase plug and receptacle?

I am buying the receptacle as well, so it will also be a 2 phase and ground receptacle. I know it seems like an obvious question but I want to make sure that I am not overlooking anything. I am only using 2 of the 3 phases, so it makes sense to only buy a plug and receptacle with 2 phases and a ground. The following is an example of the plug/receptacle I will be using:

 

[GoldDigger]

I am using NEC 400.5 to size power chords. My understanding of 400.5 is this: 3 current carying conductors in a jacket use column A. 2 current carrying conductors in a jacket use column B. I know there has to be more to it than that. Is there anything else with 400.5 that I should consider when sizing SOOW cable to be used for powerchords?

I am using the chord for use with switch rated plugs. My final question is this: the customer has a 460V 3phase supply. My machine operates on 2 phases of the 460V 3Phase. I only need to have a plug with 2 conductors and a ground that is rated for 460V? There is no reason to buy the full 460V 3 Phase plug and receptacle?

I am buying the receptacle as well, so it will also be a 2 phase and ground receptacle. I know it seems like an obvious question but I want to make sure that I am not overlooking anything. I am only using 2 of the 3 phases, so it makes sense to only buy a plug and receptacle with 2 phases and a ground. The following is an example of the plug/receptacle I will be using:
...

Is your load wired phase-to-phase on a delta (or wye) without using a neutral connection? If so, then yes you only need to carry two phase wires and an EGC. I would be careful not to get a plug which is rated for a symmetrical 460 (that is 230 volts maximum to ground). Each of your phase wires will be more than 230 volts above ground.

Wording caution to avoid problems down the road in this discussion: You are only using two of the phase wires, which gives you a single phase load which is connected across one phase (of a delta). It is not a two-phase load.

 

[fifty60]

The load is wired phase to phase. I definitely did not mean to "2 Phase" in this situation. But, it is my understanding that 3Phase is 3 seperate phases 120 degrees out of phase with each other. So wouldn't using 2 phases of this really best be worded 2 phases 120 degrees apart, and not just single phase?

The catalog does not explicitly say it is rated for 277V to ground. I do believe that by the way catalog reads that it is indeed 480/277. Please look towards the bottom right of this attached image. There is a 2P + G and a 3P + G option, the 2P + G option is what I believe to be 480/277:

 

[GoldDigger]

The load is wired phase to phase. I definitely did not mean to "2 Phase" in this situation. But, it is my understanding that 3Phase is 3 seperate phases 120 degrees out of phase with each other. So wouldn't using 2 phases of this really best be worded 2 phases 120 degrees apart, and not just single phase?

The catalog does not explicitly say it is rated for 277V to ground. I do believe that by the way catalog reads that it is indeed 480/277. Please look towards the bottom right of this attached image. There is a 2P + G and a 3P + G option, the 2P + G option is what I believe to be 480/277:

The load is a single phase load, which does not care about anything except the voltage between the two leads. It does not use any reference to ground or the third phase, so it doesn't know about any 120 degree angles. It would work just as well on 138-0-138 single phase without using the neutral as it would on two wires of three phase.
The supply is indeed two phase wires out of three, or one phase out of three depending on how you look at it.

Since the listing shows three phase and 480 volt, I would have to agree with you that 277 to ground should be fine.

 

[electrofelon]

The load is wired phase to phase. I definitely did not mean to "2 Phase" in this situation. But, it is my understanding that 3Phase is 3 seperate phases 120 degrees out of phase with each other. So wouldn't using 2 phases of this really best be worded 2 phases 120 degrees apart, and not just single phase?

Just to expand on what golddigger said from a mathematician's standpoint: Picture those two 120 degree out of phase phases on a graph. Now if you were to plot the vertical distance between the two phases on a new graph at every x value (or enough to get a decent graph), you would have a "new" single sine wave. That new single sin wave is a better representation of what the load "sees".