Fused or Non-Fused Disconnect?

[GVF]

I am installing a PV system on a barn (load-side connection). The one-line diagram represents a knife blade fused type AC disconnect between the inverter and the breaker in the MLO subpanel. The inspector who reviewed the plan stated, "Since the barn is a detached structure, the disconnect is required to be a knife blade non-fused type disconnect." Why non-fused (e.g- DU222RB) rather than fused (e.g.- D222NRB)?

 

[Dennis Alwon]

I allowed this thread but please keep the answer to just his post question.

 

[mwm1752]

Have him specify the code section.

 

[jaggedben]

I am installing a PV system on a barn (load-side connection). The one-line diagram represents a knife blade fused type AC disconnect between the inverter and the breaker in the MLO subpanel. The inspector who reviewed the plan stated, "Since the barn is a detached structure, the disconnect is required to be a knife blade non-fused type disconnect." Why non-fused (e.g- DU222RB) rather than fused (e.g.- D222NRB)?

I think the inspector is most likely wrong, because while it may be that a fused disco isn't required, that does not mean it isn't permitted. Unless this is a utility inspector enforcing some nonsensical utility rule that isn't in the NEC.

 

[pv_n00b]

There is no NEC requirement around detached structures and if a fuse or unfused disconnect is allowed. The choice to use a fused disconnect is going to be based on if you need the OCPD for downstream protection or if you need the disconnect to have a higher AIC rating than it has without fuses.