Which table provides the percentages for the transformer OCPD sizing discussed?

Which table provides the percentages for the transformer OCPD sizing discussed?

• A. Table 450.3(B)
• B. Table 430.3
• C. Table 300.5
• D. Table 200.1

Answer: (A)

When sizing the overcurrent protection for a transformer, you use a dedicated reference that translates the transformer’s rating into an appropriate OCPD size using specific percentage factors. Table 450.3(B) is the NEC table that provides those percentages for transformer OCPD sizing, covering different configurations and conditions. This makes it the correct source for the transformer-specific percentages discussed. Other tables address different topics—for example, motor protection sizing, general conductor rules, or wiring methods—so they don’t provide the transformer-focused percentages needed for this calculation.

When sizing the overcurrent protection for a transformer, you use a dedicated reference that translates the transformer’s rating into an appropriate OCPD size using specific percentage factors. Table 450.3(B) is the NEC table that provides those percentages for transformer OCPD sizing, covering different configurations and conditions. This makes it the correct source for the transformer-specific percentages discussed. Other tables address different topics—for example, motor protection sizing, general conductor rules, or wiring methods—so they don’t provide the transformer-focused percentages needed for this calculation.