What to Do When Half Your House Loses Power

Understanding Why Half the House Goes Dark

A partial power outage is confusing because some things work and some do not, with no obvious pattern. But there is a pattern if you know where to look. Your home’s electrical panel has two vertical columns of breakers. The left column and the right column are on different legs of the 240-volt service from the utility. When one leg fails, every breaker on that side of the panel loses power.

This is the most common cause of the “half my house” problem, and it has a specific signature: the dead circuits are not random. They follow the panel layout.

Step One: Check the Obvious

Before diagnosing anything electrical, check the basics. Is the utility company reporting an outage in your area? Did a storm come through? Is your neighbour’s power on? If the entire neighbourhood is affected, the issue is with the utility, not your house.

If your neighbours have power and you do not, the problem is between the utility connection and your panel.

Step Two: Look at the Panel

Open the panel cover (the outer door, not the inner cover over the wiring) and look at the breakers. A tripped breaker sits between the on and off positions. If you find one, push it firmly to off and then back to on. If it trips again immediately, leave it off and call an electrician.

If the main breaker at the top of the panel is tripped, flipping it back should restore power to the entire house. If it trips again, the problem is either in the panel or in the service entrance.

If no breakers are tripped but half the house is still dark, the problem is almost certainly a lost leg upstream of the panel.

Step Three: Check 240-Volt Appliances

Here is a quick diagnostic trick. Try turning on a 240-volt appliance: the electric dryer, the oven, or the central air conditioner. These appliances use both legs. If one leg is dead, a 240-volt appliance will either not work at all or will run at reduced power (the dryer tumbles but does not heat, for example).

If 240-volt appliances are not working properly and half the 120-volt circuits are dead, you have confirmed a lost leg. This is not a DIY fix.

What Causes a Lost Leg

The most common causes in central Kentucky:

• Utility transformer failure: the transformer on the pole serves multiple homes. If it partially fails, it can drop one leg while keeping the other.
• Overhead service drop damage: the wires from the pole to your house carry two hot legs and a neutral. Wind, ice, or a fallen branch can break one.
• Meter base connection failure: the connections inside the meter base can corrode or loosen, particularly on older installations. One leg loses contact while the other holds.
• Main breaker failure: the main breaker is a double-pole device. If one pole fails internally while the other holds, it produces the same half-house pattern.

What Not to Do

Do not open the inner panel cover to inspect wiring. The bus bars inside carry full utility voltage even when the main breaker is off, because the utility feed enters above the main breaker.

Do not attempt to tighten connections at the meter base. The meter base is utility property and the connections inside are energised at all times.

Do not continue using the working circuits at full load. A lost leg can sometimes cause voltage irregularities on the working leg that damage sensitive electronics.

When to Call

A half-house power loss that does not resolve by resetting breakers needs power outage troubleshooting from an electrician or the utility company. If the problem is at the meter or the service entrance, an electrician handles it. If the problem is at the transformer or the overhead drop, the utility handles it. An electrician can determine which one it is and coordinate with the utility if needed.

In central Kentucky, call us at (859) 493-9130 and describe what you are seeing. We can usually narrow down the location over the phone and tell you whether you need us, the utility, or both.