A continuous load is a device or circuit that stays on, such as a refrigerator or a Wi-Fi router. A non-continuous load, such as a microwave, air conditioner or electric stove, switches on and off. In the PV sector, loads can run for longer than one hour. SMA treats such a permanent load as a reason to reduce a circuit breaker's usable current, using a factor of 0.9. Breaker sizing also includes other factors, such as breakers mounted side by side with no gap and the ambient temperature inside the distribution board. Some breaker specifications state a continuous load rating. One example is the 80% rating listed for the optional AC breaker of the Solectria SGI 500XT. Equipment datasheets often state their limits as continuous current. One example is the Enphase IQ Combiner 6C, which gives continuous ampere limits for PV, battery, EV charger and backfeed circuits. The NABCEP PV resource guide lists checking continuous load calculations as a design review step under NEC Article 690.
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related_toc1 drafted · lead AC circuit breaker proposed
Breaker specifications give a continuous load rating, and breaker nominal current is reduced when the load lasts longer than one hour.
tbl=8.r1 h=f63ed489565bsec=h27 h=72d122bd272ctbl=8 h=d0feeb808b79c2 drafted · lead AC protective device sizing
SMA applies a reduction factor for loads lasting more than one hour when it sizes circuit breakers for PV systems.
sec=h27 h=72d122bd272creview note: support check: partial - The 0.9 reduction for loads over 1 h is stated as a datasheet load factor, but the passage doesn't explicitly say SMA applies it when sizing circuit breakers (implied only).
c3 drafted · lead Overcurrent protection
The optional AC breaker for the SGI 500XT lists a continuous current pickup setting and a continuous load rating.
tbl=8.r1 h=f63ed489565btbl=8 h=d0feeb808b79related_to c3