# Transformer OCP



## don_resqcapt19 (Jul 18, 2010)

The transformer primary is protected at less than 125% so the code does not require that the transformer secondary be protected. As long as the secondary conductors have an ampacity of at least 100 amps the installation is code compliant.
In general the rules for the protection of the transformer are in Article 450 and the rules for the protection of the secondary conductors are in 240.21(C).


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## micromind (Aug 11, 2007)

don_resqcapt19 said:


> The transformer primary is protected at less than 125% so the code does not require that the transformer secondary be protected. As long as the secondary conductors have an ampacity of at least 100 amps the installation is code compliant.
> In general the rules for the protection of the transformer are in Article 450 and the rules for the protection of the secondary conductors are in 240.21(C).


I could very easily be reading it wrong, but it seems to me that both 240.4(F) and 240.21(C)(1) would require secondary protection for this type of transformer.


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