Good afternoon everyone. I have a transformer that is 1.5KVA at 460V, and it is rated for 50/60Hz. I would like to use it at 400V 50Hz on the primary side. The transformer only has primary taps for 460V. If I use 400V on the primary, then the KVA will derate at the same proportion as the voltage. So I will be left with a 1.25KVA at 400V. Does the NEC require that I calculate my fuse sizes from this new 1.25KVA value are we still required to use the 1.5KVA nameplate value?
