If the secondary device is a panelboard, and the mains are rated at 800-amps, then you should not have received a defect.
It should have been accepted with 250-amp fuses on the primary, when the secondary equipment has the ability to withstand the transformer inrush current.
The Ontario Electrical Safety Code allows protection of a panelboard using overcurrent protection in the primary of a transformer provided:
when the panelboard rating, adjusted by the turns ratio of the transformer, equals or exceeds the primary overcurrent device rating,
the primary overcurrent device rating is adequate to withstand the transformer inrush current, (Rule 2-034 page 16) and
there is permanent marking on the primary disconnect switch to indicate the maximum fuse size and type to be used for continued protection (Rule 2-100(3) page 17)
Minimum conductor sizes and minimum panelboard ratings can be based on the rating of the overcurrent device.
The Appendix B note to Rule 26-256 (page 464) provides a "rule of thumb" for determining the adequacy of the overcurrent device to withstand the transformer inrush current for dry type transformers. Specifically:
The current which causes the overcurrent device to operate at 0.1 seconds must exceed 12 times the transformer rated primary current, and
The current which will cause the overcurrent device to operate at 0.01 seconds must exceed 25 times the transformer primary rated current.
Where there is a question concerning a particular installation, the contractor or consultant should:
1-consult the transformer manufacturer about the inrush currents,
2-the overcurrent device supplier concerning the operating times for the overcurrent devices, and
3-be prepared to show evidence the overcurrent device can carry the inrush currents.