Indoor transformer 75kVA, not single phase 2W or delta-delta 3W, can MCB qualify as OCP for the secondary side?

[jap]

Correct me if I'm wrong but the ability to lock out the primary side doesn't necessarily negate the benefit of a secondary OCPD outside the panelboard. The primary OCPD for a transformer may be sized as high as 2.5X of FLA to compensate for inrush, therefore the arc flash current as a multiple of rated current of the primary OCPD is likely to be much lower (and hence much higher clearing time) than that for a secondary side OCPD. I bring this up because there may be occasion to work live in the secondary panel.

Again, a circuit breaker is an acceptable means of overcurrent protection for the secondary side of a transformer.

When you start discussing the need to reduce arc flash, and working in live panels, or safety, it gets into a whole different line of things that can be done to help reduce the hazard.

By the OP's original question, (although all valid points have been brought up since), I don't think think his original question was anything other than if a breaker would qualify as a means of OCP for the secondary of the transformer in lieu of a fused disconnect.

Augie took care of that answer in post #3.

JAP>