OCPD on 24V side for 1000VA transformer

[victor.cherkashi]

Turnstile’s manufacturer provides 1000VA, 1-phase, 120V/24V transformer to power several turnstiles. Transformer installed 70ft away from turnstiles. I got wiring diagrams for review from Turnstile’s contractor, but there was no OCPD on 24Volt side. Diagram shows two circuits on 24V side (3#12AWG each). To my question why there is no OCPD, they said we never saw OCPD devices installed on 24V side.

I requested to install 20A breaker for each 3#12AWG circuit on 24V side. Since it is not circuit class 1,2,3 I applied standard rules as for 120V, 208V, 480V etc.

Just want to hear your opinions, maybe I missed something in NEC.

 

[texie]

If this a 2 wire 24 volt secondary the primary OCPD can also protect the secondary and conductors as long as it is sized correctly.
Edit to add: Just noticed you said 2 #12 circuits. The output of the transformer is about 42 amps. The #12s will need OC protection.

 

[victor.cherkashi]

If this a 2 wire 24 volt secondary the primary OCPD can also protect the secondary and conductors as long as it is sized correctly.
Edit to add: Just noticed you said 2 #12 circuits. The output of the transformer is about 42 amps. The #12s will need OC protection.

There will be 20A OCPD on primary. Ratio is 120/20=5.

20Amp*5=100A

Per my understanding they need to install 100A rated wires on 24V side to get away with OCPD on 24V side of the transformer.

 

[don_resqcapt19]

There will be 20A OCPD on primary. Ratio is 120/20=5.

20Amp*5=100A

Per my understanding they need to install 100A rated wires on 24V side to get away with OCPD on 24V side of the transformer.

I don't see how that complies with Table 450.3(B) as that is above 167% of the primary current and the use of a a primary OCPD that exceeds 13.91 amps requires that the transformer have secondary OCPD. Note that there is no "round-up" note for the primary protect in the less than 9 amp column.