Table 450.3(B) Maximum Rating or Setting of Overcurrent Protection for Transformers 1000V
and Less (as Percentage of Transformer Rated Current)
| Protection Method |
Primary Protection |
Secondary Protection (See Note 2) |
| Currents of 9 Amperes or More |
Currents Less Than 9 Amperes |
Currents Less Than 2 Amperes |
Currents of 9 Amperes or More |
Currents Less Than 9 Amperes |
| Primary only protection |
125% (See Note 1) |
167% |
300% |
Not required |
Not required |
| Primary and secondary protection |
250% (See Note 3) |
250% (See Note 3) |
250% (See Note 3) |
125% (See Note 1) |
167% |