Nec Ocpd Ratings: 450.3(B)
NEC overcurrent protective device (OCPD) ratings — standard ampere ratings for fuses and circuit breakers per Section 240.6(A), motor branch circuit protection per 430.52(C)(1), overload relay sizing per 430.32, and transformer OCPD sizing per 450.3
| nec section | record id | description | device type | location type | primary ocpd 9a or more | primary ocpd less than 2a | primary ocpd less than 9a | protection method | rating amp (A) | secondary ocpd 9a or more | secondary ocpd less than 9a | secondary protection pct | standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 450.3(B) | 450.3B_primary_and_secondary_protection | — | — | — | 250% | 250% | 250% | Primary and secondary protection | — | 125% | 167% | — | NEC (NFPA 70) 2017 Table 450.3(B) |
| 450.3(B) | 450.3B_primary_only_protection | — | — | — | 125% | 300% | 167% | Primary only protection | — | Not required | Not required | — | NEC (NFPA 70) 2017 Table 450.3(B) |
| 450.3(B) | circuit_breaker_supervised_125A | Transformer secondary protection (≤ 1000V secondary) — supervised location, CB | circuit_breaker | supervised | — | — | — | — | 125 | — | — | 125 | NEC (NFPA 70) 2023 Table 450.3(B) |
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