Table 450.3(B) Maximum or Less?

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When designing the OCPD for a transformer using this table how does the designer or engineer decide what OCPD value to use? For example we have a 1Ø, 1kva 480-120 volt transformer, how would you decide what size primary and secondary protection to use given the maximum values listed in Table 450.3(B)?

 

[Smart $]

Take other parameters into consideration, namely load and wire size.

For 1kVA, I'd just use the maximum permitted, provided it don't exceed the ampacity permitted for the wire size I want to use.

 

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I figured that most just use the maximum allowable value but was curious as to whether or not there was a rule of thumb for determining the OCPD size. For my application I believe that they will be providing 5 amp primary and 12 amp secondary Type CC fuses which fits in the 250% primary and 167% secondary range.