Code section for arc flash label

[Strathead]

I am not sure what will happen if the OCPD does not perform as expected.

For example, if the OCPD cannot withstand the fault due to a low AIC, will it open the circuit faster or slower? In that case, is the TCC still valid for calculating the fault-clearing time?

Same idea for 208v fuse in 480v system.

It depends. The arc can melt the contacts so quickly that the fuse together and don't open at all, or they can blow apart possibly compromising the area around the breaker.

 

[jim dungar]

I am not sure what will happen if the OCPD does not perform as expected.

For example, if the OCPD cannot withstand the fault due to a low AIC, will it open the circuit faster or slower? In that case, is the TCC still valid for calculating the fault-clearing time?

Same idea for 208v fuse in 480v system.

A 300V fuse can only be installed in a 300V switch which means the line to ground installation may fail while interrupting a 480V fault resulting in the OCPD not clearing the fault thus negating the Arc Flash calculation that used this device's clearing time.

For an underrated OCPD, the device's clearing time may also be negatively compromised also negating the AF calculation.

Added the word not.