Parrallel circuit to a wye delta contactor

[PhaseShift]

We have a 480V 3 phase wye delta motor contactor controlling a motor. The drawing calls for a parallel feed to be brought from the mcc to the main contactor and then jumpered over to the delta contactor. The contractor is saying that he will bring one set of the parallel feeder to the main contactor and the other set to the delta contactor. He will then put a jumper between contactors.

I don't believe that you can do this and am trying to explain why. The first thing that comes to mind I'd the fact that parallel feeders need to land on the same termination point and not on seperate contactors (even I jumpered)

Besides what I mentioned above are there other reasons why this cannot be done this way?

 

[crossman gary]

From a "will it work" standpoint, I see no problem with doing the installation as the contractor says. The little bit of extra length from the jumper is not going to cause any practically noticable variation in current flow as compared between the individual paralleled conductors.

Now to the Code.... my first inclination is that it would be a violation, but this may be based on assumptions I have made. Now that I went back and carefully read 310.4, I'm not quite so sure.


310.4(A) "...shall be permitted to be connected in parallel (electrically joined at both ends).

Does the contractor's suggestion meet this? I say yes. The language does not say the wires must be terminated on the same lug. It says they must be electrically joined at both ends. I don't think we can automatically assume that the jumper is part of the parallel conductor arrangement. It is part of the termination means. The jumper is the "electrically joined at both ends" part.

310.4(B) gives the requirements on same length, same conductor material, etc.

Does the contractor's suggestion meet these? As long as he follows the guidelines, and he certainly could, then he is okay on the above.

I'm definitely interested in hearing other perspectives.