PEC Cable Sizing

Continuous Loads Under PEC: When the 1.25× Factor Applies

Not every load gets the continuous-load safety margin — here is how to tell which ones do.

A 1.25× safety factor for continuous loads shows up across PEC, AS/NZS, and NEC alike, but it's not applied blindly to every circuit — it specifically targets loads expected to run at or near full current for an extended period, commonly defined around the three-hour mark.

What Typically Counts as Continuous

• Lighting circuits that stay on for hours at a stretch
• HVAC and refrigeration compressors running long duty cycles
• Water pumps in continuous-duty applications
• Solar PV output — the array can produce near-rated current for hours every sunny day, which is exactly why PV circuits get their own dedicated multiplier logic

What Typically Doesn't

A load that cycles briefly — a momentary motor start, a short-duration appliance — doesn't automatically carry the same 1.25× continuous-load margin, though it may have its own separate sizing consideration (like a motor's starting current surge, covered in a dedicated article).

Confirm whether your specific load qualifies as continuous before applying the multiplier in the PEC Cable Sizing calculator.

Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks

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