Why did half my house lose power?

Half your house losing power is typically caused by a lost leg of power from your electrical panel or utility service - this is a common but potentially serious electrical issue that requires immediate attention.

Your home receives 240-volt electrical service through two separate 120-volt "legs" or phases. When one of these legs fails, roughly half your circuits lose power while the other half continue working normally. This creates the distinctive pattern where some rooms work fine while others are completely dead.

The most common causes include:

A tripped main breaker in your electrical panel is often the culprit. Unlike regular circuit breakers that protect individual circuits, your main breaker can partially fail, cutting power to one leg while maintaining the other. Check your electrical panel - the main breaker at the top should be firmly in the "ON" position. If it appears loose or in the middle position, try turning it fully OFF then back ON.

Utility service issues are another frequent cause. A damaged transformer, loose connection at the meter, or problems with Hydro Ottawa's service lines can result in lost voltage on one phase. This is especially common during storms, high winds, or after utility maintenance work.

Failing electrical panels, particularly older Federal Pacific or Zinsco panels common in Ottawa homes built in the 1960s-80s, can develop internal connection problems. These panels are known fire hazards and often lose proper contact on one bus bar, affecting half the circuits.

Immediate safety steps: First, check if your neighbors are experiencing similar issues - if so, call Hydro Ottawa at 613-738-6400 to report an outage. If it's isolated to your home, avoid using high-power appliances on the working circuits, as they're now carrying extra load. Don't attempt to force breakers or remove the panel cover.

This situation requires professional diagnosis because working with main electrical components involves lethal voltages. In Ontario, only ESA-licensed electricians can safely diagnose and repair service entrance issues. The problem could be at your meter connection, main panel, or require coordination with Hydro Ottawa for utility-side repairs.

For immediate assistance with power loss affecting half your home, contact a licensed electrician for emergency service - this isn't something to wait on, as the remaining circuits are under increased stress and the underlying cause could worsen.