Transformer secondary protection required?

[T.M.Haja Sahib]

If the secondary conductors are 3m or less you can use (C)(2) to protect them instead of the primaries. Note that (C)(2) protects the secondary conductors without using OCPD. Example: 240.21(C)(2)(1)b mentions the poster's 200A OCPD as "the overcurrent-protective device at the termination of the secondary conductors." Here they've avoided calling the OCPD at the far end of the run "Secondary OCPD" because it's not being used for the transformer protection.

If the OCPD on the secondary side does not exceed 125% of transformer full load current for the condition stated in post#79, it can be considered that the transformer is protected.

 

[pfalcon]

... From what I see the secondary 200A breaker does not provide adequate secondary protection of the transformer. ...

If the OCPD on the secondary side does not exceed 125% of transformer full load current for the condition stated in post#79, it can be considered that the transformer is protected.

The implication in the OP is he trying to meet 450.3(B) P&S protection. David pointed out that by using 70A primary he could move to the primary-only row on the table.

Left out on that suggestion is that by going to primary-only he may have violated 240.21 for conductor protection. I stress maybe. The data for evaluating that wasn't provided. But a warning to meet 1 of the 6 methods of conductor protection is appropriate and sufficient until he expands the question.