300v cable rating connected into an MCC using 380v?

[clipski]

Hello, First time user of this blog and I am trying to determine the real ruling about cable ratings and their uses
I have a system which is run from a 480vac MCC panel in which 4 rotator motor drives are used to turn large pipe.
The motors have encoders attached to them in which the encoder cables feed back to the MCC. The cable is rated
for 300v and outdoors. It is routed through rigid conduit from the motor back to the MCC. My question is if the
MCC utilizes 480vac, would I need theses encoder cables to be rated 480v or higher as well. Currently they are
rated at 300v. The encoders signals are 120vac

Thanks for any feedback

 

[GoldDigger]

Hello, First time user of this blog and I am trying to determine the real ruling about cable ratings and their uses
I have a system which is run from a 480vac MCC panel in which 4 rotator motor drives are used to turn large pipe.
The motors have encoders attached to them in which the encoder cables feed back to the MCC. The cable is rated
for 300v and outdoors. It is routed through rigid conduit from the motor back to the MCC. My question is if the
MCC utilizes 480vac, would I need theses encoder cables to be rated 480v or higher as well. Currently they are
rated at 300v. The encoders signals are 120vac

Thanks for any feedback

If the encoder signals are supplied by a 480 to 120 transformer in the equipment (e.g. in the MCC), then the signal wires do not need to be insulated to 480V unless you are trying to run them in the same raceway or cable with the 480V power wiring.
Depending on how the manufacturer built the panel and encoders, the wiring may also be Class 2 or Class 3 limited power which allows some additional options for wiring methods that you would not have otherwise.
There may need to be partitions inside the panel separating the two voltages or separating the power from Limited Power sections.