Short Circuit Study and SCCR
Short Circuit (Fault Current) Study / Analysis
Short Circuit (Fault Current) studies are required by NEC to insure that existing and new equipment ratings are adequate to withstand the available short circuit energy available at each point in the electrical system. IEEE 242-1986 is used to determine if fault currents exceed equipment ratings which are capable of extensive equipment damage and are a serious threat to human life.
All electrical distribution equipment installed must be able to withstand the available short circuit current, and calculations should be periodically maintained or updated whenever major changes are made to the electrical system or if any replacement contact kits are needed.
DELIVERABLES OF SHORT CIRCUIT STUDY
A typcial short circuit study includes:
- Short circuit calculations, which highlights any equipment that is
ascertained to be underrated as specified
- Suggested modifications to rectify the underrated equipment; (trip
sizes within the same frame, the time curve characteristics of induction
relays, CT ranges, etc.).
SCCR Short Circuit Current Rating
SCCR studies are used to determine if the electrical components being installed are rated to handle the available short circuit current per compliance with NEC 110.10. Equipment or assemblies installed shall have an SCCR rating on them prior to installation.