Hello,

A 25 kva transformer is being installed. When sizing my OCPD for the secondary conductors and the single phase 120/240 panel board (70' from transformer) I multiplied secondary current by 125% (104 x 125% = 130 amps). If I use the next size up OCPD, I get a 150 amp OCPD. I was looking at a single phase chart from Mike Holt that states the 25kva single phase transformer should have a secondary OCPD of 125 amps. Would anyone be willing to help clarify which OCPD (125a or 150a) would be correct and why?

Chart: https://www.mikeholt.com/files/PDF/T...rmer_Chart.pdf

Thank you,

Carl

A 25 kva transformer is being installed. When sizing my OCPD for the secondary conductors and the single phase 120/240 panel board (70' from transformer) I multiplied secondary current by 125% (104 x 125% = 130 amps). If I use the next size up OCPD, I get a 150 amp OCPD. I was looking at a single phase chart from Mike Holt that states the 25kva single phase transformer should have a secondary OCPD of 125 amps. Would anyone be willing to help clarify which OCPD (125a or 150a) would be correct and why?

Chart: https://www.mikeholt.com/files/PDF/T...rmer_Chart.pdf

Thank you,

Carl

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