Code Comparison Cable Sizing
All three codes apply some form of a 1.25× safety margin to continuous loads, but the exact application and terminology differ.
A continuous-load safety margin — commonly a 1.25× factor — shows up under PEC, AS/NZS, and the NEC alike. The underlying reasoning is identical (a load running near full current for hours needs extra thermal headroom), but each code frames and applies it slightly differently.
All three recognize that a load sustained at or near full current for an extended period (commonly defined around three hours) stresses a conductor differently than a brief peak — and all three build in a margin to account for it.
| Code | General approach |
|---|---|
| PEC | Applied via continuous-load provisions in the code's ampacity and protection sections |
| AS/NZS | Reflected in demand factor and diversity considerations alongside general ampacity requirements |
| NEC | Explicit 125% factor referenced directly in multiple Articles (210, 215, 430 for motors specifically) |
Never assume a continuous-load factor from one code carries over numerically identical to another — confirm the specific provision under whichever code actually governs your project.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks