Electrical load is the amount of power drawn by devices on a circuit. A single light bulb is a small load. A clothes dryer is a large one. A factory with motors and furnaces is a very large one. Utilities measure load in watts, kilowatts, or megawatts, and track it minute by minute.

Load varies by time of day and season. It peaks in the morning when people wake up and in the evening when they return home. Summer peaks come from air conditioning. Winter peaks come from heating. Utilities must have enough capacity to meet the highest peak, even if it lasts only a few hours a year.

Managing load is a core job. Utilities forecast demand, dispatch generation, and call on demand response. Homes and businesses can shift load by running appliances off-peak or pre-heating and pre-cooling. As more devices electrify, from cars to heat pumps, load patterns will change. Grid planners are watching closely.

Common terms

• Peak load
• Base load
• Load factor
• Load profile
• Load shedding