NEC 409/UL 508A

NEC defines the Short Circuit Current Rating (SCCR) as: "The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria."

What this means is that the SCCR is the maximum short-circuit current equipment can survive without damage or without causing a hazardous condition. SCCR applies to equipment and components. It does not apply to fuses or breakers, which are intended to interrupt current. However, it does apply to the panel where the interrupt devices are installed as well as the equipment they protect.

However, the SCCR and the interrupt device are related. For example, can equipment withstand short circuit conditions until the interrupt device stops the current flow? What is the maximum current that can exist during the time it takes the interrupt device to stop the current flow?

Both NEC 409 and UL508A require the marking of industrial control panels with their SCCR. This means that anyone who assembles electrical equipment such as panels, disconnect switches and power circuit components is required to test the equipment and label them with their SCCR. This includes manufacturers, contractors, system integrators and end users.

The SCCR typically is included on the equipment nameplate label, along with such information as the name and location of the manufacturer, the panel type, electrical wiring diagram or a reference number to the electrical drawings, and various other information.

It is crucial that this label be permanent and the information it contains be specific to the equipment. The best way to make these labels is using a DuraLabel printer. With DuraLabel you can print labels, of various sizes, using nearly any software you have. Labels can include text, diagrams and logos. And each label can be custom designed with as many copies as needed quickly printed.