What is load shedding on a home generator?

Load shedding on a home generator is the process of automatically or manually disconnecting non-essential electrical circuits when your generator's capacity is being exceeded or approached, ensuring the most critical systems in your home stay powered.

When a generator is running, it has a fixed power output measured in watts or kilowatts (kW). Unlike your utility connection from Hydro Ottawa, which can supply essentially unlimited power on demand, a generator has hard limits. If too many appliances run simultaneously and draw more power than the generator can produce, it will overload and shut down — leaving you with no power at all. Load shedding prevents this by prioritizing which circuits stay on.

How it works in practice depends on your setup. Basic generator installations use a manual transfer switch where you physically decide which circuits to power. More sophisticated systems use an automatic load management panel that monitors power draw in real time. When demand spikes — say your central air conditioner compressor kicks on while the electric stove and water heater are already running — the system automatically drops lower-priority circuits (like outdoor outlets or basement lighting) to protect the generator and keep critical loads like your furnace, refrigerator, and medical equipment running.

Sizing and load shedding go hand in hand. A properly sized whole-home generator (typically 14kW–22kW for an average Ottawa home) may rarely need to shed load. Smaller standby or portable generators (7kW–12kW) almost always require some form of load management. This is one reason why generator sizing is so important — an undersized unit forces constant load shedding and puts more wear on the generator.

From an Ontario code perspective, generator installations require an ESA permit and must include a proper transfer switch to prevent back-feeding onto Hydro Ottawa's lines — which is extremely dangerous for lineworkers. The transfer switch is also where load shedding controls are typically integrated.

The practical takeaway for Ottawa homeowners is that if you're considering a generator for winter ice storms or summer outages, discuss your critical loads with your electrician upfront. Make a list of what absolutely must run (furnace, fridge, sump pump, medical devices) versus what's nice to have. This shapes both the generator size recommendation and how your transfer switch and load management panel get configured.

If you're exploring a generator installation, Electrical Ottawa can assess your panel, calculate your critical loads, and recommend the right generator size and load management setup for your home. Feel free to reach out for a free consultation.