Last edit: 12/07/2023
Regarding the determination of the industrial control panel SCCR, Rule 4.13 was completely rewritten. The following rules are now present:
- 13.1 Control circuits tapped from feeder circuits
- 13.2 Control circuits tapped from the load-side of a motor branch circuit protective device
- 13.3 Determining assembly SCCRs
The latest rule has the following important note:
[C22.2 N°286: 2023] 4.13.3 … Notes:
1) The default method for determining the industrial control panel’s overall SCCR is to apply the lowest SCCR or interrupting rating of any individual component within the primary circuit of the assembly.
2) An alternative technique is to determine the short-circuit ratings of the individual power circuit components, investigate opportunities to increase the SCCR of individual circuits using current limiting components, and then determine the final SCCR for the complete assembly.
- 13.4 High fault short-circuit current rating of bus bars
- 13.5 Power transformers used to limit the available short-circuit current
- 13.6 Current limiting circuit breakers used to limit the available short-circuit current in feeder circuits
- 13. 7 Class CC, G, J, L, RK1, RKS, or T fuses used to limit the available short-circuit current in feeder circuits. Please refer to an abstract from Table 22 shown in this page.
- 13.8 Current-limiting circuit breakers and current-limiting fuses
- 13.9 Overall SCCR of the panel
- 13.10 Isolated power circuits
- 13.11 Components connected to the secondary circuit of a transformer