UL 508 A - Short-circuit current rating
Systems which are to be set up within the US must be labeled with an officially certified SCCR value since April 2006. This is to be documented on the power rating plate of the control cabinet or system by indicating the short-circuit current rating. This regulation comes from the National Electrical Code (status 2005), which refers to UL 508A.
The SCCR value indicates the short-term short-circuit rated current which an assembly or system can withstand. Since the maximum possible short-circuit currents vary, depending on the set-up location and feed line, UL inspectors demand corresponding labeling and documentation at the system acceptance.
For circuits in which the installation of higher documented components is out of the question, by connecting a correspondingly high-current listed fuse terminal block upstream, the entire circuit can be rated higher. The fuse terminal blocks UK 10,3-CC HESI N and UK 27-J HESI allow the SCCR to be rated higher to 200 kA for circuits connected downstream.
Thus, you are essentially independent of the SCCR values of the used modular terminal blocks or components when having your system qualified.
User advantages: By using Phoenix Contact products, you achieve much higher planning security for all industrially used systems set up within the scope of the UL.