Hi,
I have a 480 V switch gear we are going to feed a new maint building from. We are going underground about 50 feet from the MCC to the new building. We wont need a disco for the primary of the transformer but will for the secondary right?

Thanks

You will need a disconnect at the building to satisfy 225.31. Transformers do not require disconnects, but they do require over current protection per Article 450. The feeder OCPD will provide the required primary protection. Secondary protection for the transformer many not be required, but in most cases the secondary conductors require protection at or near the transformer per 240.21(C).
Don