Two feeders each move the same 2,880 MWh over a 30-day month. One serves an office park that runs nearly flat around the clock. The other serves a residential neighborhood that stays quiet all day and spikes hard from 5 to 9 p.m. Same energy delivered, same kilowatt-hours billed. Which feeder is using its wires better, and why would the utility care?
The flat feeder is, and the load hierarchy shows why. Instantaneous load is what a feeder draws at a single moment. Demand is that load averaged over a fixed interval, usually 15 minutes on a utility meter, never a one-second reading. Peak demand is the highest of those interval readings across the period. Load factor ties them together: it is average load divided by peak load over the same period, a unitless ratio that can never exceed 1 because the average can never sit above the peak.
Run the hook through it. Same 2,880 MWh over 720 hours means both feeders average 4 MW. The office park peaks near 4.5 MW, so its load factor is about 0.89. The residential feeder peaks at 10 MW to serve the same energy, so its load factor is 0.4. Identical energy, very different shapes.
The reason a utility cares is that the transformer, the conductor, and the substation breaker are all sized to carry the peak, not the average. A low load factor means capacity was bought, installed, and energized that sits idle most hours of the month. The peaky residential feeder needed more than twice the equipment rating of the office park to deliver the exact same energy.
When you size a feeder transformer or read a customer’s demand profile, load factor tells you how hard the money on the pole is actually working. A flat load pattern delivers more energy per dollar of installed capacity than a peaky one. Just do not confuse load factor with the diversity, demand, and coincidence factors coming next lesson: those are different ratios that compare separate customers’ peaks against each other, not one feeder’s average against its own peak.
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