Breaker for 20A boost transformer?

Not open for further replies.


New User
St. Paul
Factory maintenance
Hi, seeking a electrcian's comment on this if possible:

We just acquired a used single-phase compressor that must run on 230v. Our service is 208Y/120. I've got my eye on a boost transformer that should meet our needs (current draw on the compressor is 12.7 Amps). The transformer itself has a primary side of 208v /20 Amps and a secondary of 230v / 18.6 Amps.

I am just wondering if it's OK & proper to protect that circuit, which will have the transformer inline, upstream of the compressor, with a 20 Amp breaker at the main panel, or if I need to do a standard 125% increase for the breaker/circuit size. There is 12 gauge wire already run to the location so I'm especially motivated to keep it all on a 20A breaker if possible, but I do not know if the transformer, with it's primary 20A rating, means I need to go up to a higher breaker and wire size for any reason.

Many thanks!
Not open for further replies.