In industrial application, we have a MV 4.16kV Transformer that is feeding one MCC line up. Both Transformer and MCC are located outdoor, specific for MCC is located under shelter. We have an initiative to add 1 MCC line up that will be tied in directly to the secondary side of transformer. Is this comply with NEC? Please for your feedbacks and comments. Thank you.
Transformer Feeding Two MCCs
- Thread starter glluga
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electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Generally you must provide protection for the secondary conductors 240.21(C), and for the transformer itself (450.3). I know the transformer protection values are different for MV, but I am not sure offhand if there is anything different for the conductors being >1kv. Check in the MV portion of 240.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
In general this is permissible.
It is not clear to me from your post if the 4160 V xfmr is 4160 V on the primary or secondary side. It would be code legal either way but could be a little different implementation wise.
For the transformer we have already installed 87T protection in which CTs are installed on the HV and LV side of transformer, and will trip HV side breaker. Do we still need protection for secondary if each lineup of the MCC is having CL Fuse as incoming side protection?
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