New Feature All Codes
A new calculator finds the prospective fault current at the end of a cable run — using each code tab's own already-verified cable data.
OhmWorks now calculates prospective short-circuit (fault) current — a new calculator added to the PEC, AS/NZS, and NEC tabs alike.
Given a source impedance (either a known fault current at the origin, or a directly measured impedance) plus a cable's material, size, and length, it calculates the current that would flow if a bolted fault occurred at the far end of that run — the number a protective device's breaking capacity has to be rated at or above.
Rather than introducing new tables, each code's version pulls from cable impedance data OhmWorks already had, fully verified for the existing Cable Sizing and Voltage Drop calculators — the same PEC mV/A/m figures, the same AS/NZS 3008.1.1 voltage-drop tables, the same NEC Chapter 9 Table 8 resistance data.
This version calculates fault current only. It doesn't check a specific breaker or fuse's thermal (I²t) withstand against its trip curve — that needs manufacturer-specific device data OhmWorks doesn't have reliable access to yet. What it does give you is real, and it's built to make that scope clear rather than imply more than it delivers.
Every Short Circuit Analysis screen includes an expandable "How this works & definitions" section — what prospective fault current means, why source impedance matters, why a breaker's breaking capacity has to match it, and why fault current drops the further you get from the source.
Find it under any of the PEC, AS/NZS, or NEC tabs.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks