I represent a company in Germany manufacturing machinery for the concrete precast industry worldwide. We want to standardize our electrical installations in a way that will be accepted worldwide. In this regard, we have chosen to use the UL standards for our switch cabinets and panel wiring. My question:Is it allowed to connect several three phase electrical motors from a main switch cabinet to a secondary junction box connecting between the two points with a multi-conductor cable? In other words, If I had for instance 4 motors at a general location on the machine where all of the contactors and circuit protection is centrally located in a main panel away from the machine. Can I use a 16 conductor cable connecting from the main panel to a junction box that connects this mulit-conductor cable to 4 individual 4 conductor cables leading to each motor. Further, could a 13 conductor cable be used where three conductors were allocated for each motor sharing 1 common grounding lead between all four motors?
NEC Code use of multi conductor cables for motor loads
- Thread starter hvandusen
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petersonra
Senior Member
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- Northern illinois
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- engineer
Re: NEC Code use of multi conductor cables for motor loads
If it is part of a factory manufactured assembly, than you can do this per UL 508a standards, assuming UL 508a allows this.
If however, the cable would be made up and wired in the field, than NEC standards would apply since this would be considered part of the installation rather than part of the factory assembly.
I am not sure how you will deal with the color coding issues though. These are different. For instance,in the US neutral is white, in Europe it is brown. You would also need to use UL listed wire/cable for products coming to the US. US wire is sized in AWG, while European wire is sized in the metric system, and the two are not directly compatable.
As long as the green wire is sized for the largest OCPD, than a single green wire is adequate.
[ June 10, 2005, 12:39 PM: Message edited by: petersonra ]
If it is part of a factory manufactured assembly, than you can do this per UL 508a standards, assuming UL 508a allows this.
If however, the cable would be made up and wired in the field, than NEC standards would apply since this would be considered part of the installation rather than part of the factory assembly.
I am not sure how you will deal with the color coding issues though. These are different. For instance,in the US neutral is white, in Europe it is brown. You would also need to use UL listed wire/cable for products coming to the US. US wire is sized in AWG, while European wire is sized in the metric system, and the two are not directly compatable.
As long as the green wire is sized for the largest OCPD, than a single green wire is adequate.
[ June 10, 2005, 12:39 PM: Message edited by: petersonra ]
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