Interrupt Rating (IR) vs SCCR

[fifty60]

I understand that SCCR and IR are not the same thing. Fuses and Circuit breakers have IR's, and contactors and other power components have SCCR's. The SCCR of an entire equipment cannot be greater than the lowest IR or the lowest SCCR. The SCCR for the equipment is typically the lowest SCCR or IR of the power components.

With that being said, is there any benifit in knowing the IR of a machine if you already know the SCCR? I think it i would just be confusing to list both on a single machine. Someone may look at a machine and think "Wow, it has an IR of 25KA", but the SCCR is only 5KA.

I know there is a requirement to put the SCCR on equipment labeling, but is there also a requirement to put the IR on the label? Was the IR on the label before the SCCR labeling requirement came into affect several code cycles ago?

 

[packersparky]

I understand that SCCR and IR are not the same thing. Fuses and Circuit breakers have IR's, and contactors and other power components have SCCR's. The SCCR of an entire equipment cannot be greater than the lowest IR or the lowest SCCR. The SCCR for the equipment is typically the lowest SCCR or IR of the power components.

With that being said, is there any benifit in knowing the IR of a machine if you already know the SCCR? I think it i would just be confusing to list both on a single machine. Someone may look at a machine and think "Wow, it has an IR of 25KA", but the SCCR is only 5KA.

I know there is a requirement to put the SCCR on equipment labeling, but is there also a requirement to put the IR on the label? Was the IR on the label before the SCCR labeling requirement came into affect several code cycles ago?

A piece of equipment will not have an interrupting rating. It may have an SCCR rating. An interrupting rating will be found only on breakers and fuses.

 

[Jraef]

The IR of the protective device is a factor in determining the SCCR but any value higher than the SCCR is irrelevant, so there is no requirement to show it, in fact it can be confusing to those not yet familiar with all of the terminology.

There really is little excuse for ending up with a 5kA SCCR label any more, it just means someone didn’t care enough about it to do a thorough investigation of the components they used; i.e. laziness.