transformer protection

[jmfelectric]

greetings forum

transformer protection is the question this morning.
450.3(B) note 1, tells us next size up standard protection if the current is 9amps or more.

for 9amps or less and 2amps or less where does it state that we can go next standard size down?

thanks
john

 

[iwire]

greetings forum

transformer protection is the question this morning.
450.3(B) note 1, tells us next size up standard protection if the current is 9amps or more.

for 9amps or less and 2amps or less where does it state that we can go next standard size down?

thanks
john

No need, the tables are maximums not minimums.

 

[jumper]

Why do you wish to go down? Just curious.

 

[templdl]

Is secondary protection being provided? When providing protection for transformers a properly sized secondary OCPD will protect the transformer from overload while the pri. OCPD will protect the upstream distribution system should the transformer itself short circuit and fail. Take away the sec. OCPD and now you have to rely on the pri. OCPD for transformer overload protection if alowed by the NEC art 450.