Breaker sizing for a circuit

[EITsingh]

HEllo all,

I have a circuit that includes a transformer feeding a control panel which feeds a condenser (multiple fans). I am looking to size my branch circuit breaker for it and was wondering if I will base it on Transformer primary or actual load.

 

[jraef]

Assuming that your load is less than the transformer rating, your control panel has branch protection for the condenser and the transformer has secondary protection, you would size it for the transformer primary. If you size it for the load and try to eschew the secondary protection, you run the risk of the transformer inrush not allowing your breaker to hold in.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[EITsingh]

what if the manufacturer recommended MOCP is less than that of the calculated based on the transformer, shall I go with manufacturer or still base it on code sizing?

 

[EITsingh]

to add to the last comment, the control panel has secondary protection for each fans.

 

[Parchie]

what if the manufacturer recommended MOCP is less than that of the calculated based on the transformer, shall I go with manufacturer or still base it on code sizing?

If that is the case, the sizing given by the manufacturer is on the safe side, IMO. The protection will be very near the actual continuous current.