When half of your house loses power while the other half remains functional, the issue typically stems from a failure in one phase of your home's split-phase electrical system. This scenario often occurs due to a lost "hot leg" (one of the two 120V power lines), a tripped main breaker, or localized problems like a faulty GFCI outlet or overloaded circuit. Immediate steps include checking your circuit breaker panel for tripped switches, resetting GFCI outlets, and verifying if 240V appliances (like dryers or ranges) are operational—this helps determine whether the problem originates from your home's wiring or the utility supply. If basic troubleshooting fails to restore power, the issue may involve utility-side failures (e.g., transformer problems) or internal wiring faults, both of which require professional intervention.

Key findings from the sources:

• First actions: Unplug appliances, reset tripped breakers, and check GFCI outlets ^[2]. Test 240V circuits to assess the scope of the outage ^[3].
• Common causes: Lost hot leg (one phase failure), loose/main breaker issues, or utility-side problems like transformer faults ^[5][7].
• When to call an electrician: If breakers/GFCIs reset but power isn’t restored, or if you notice burning smells, sparking, or flickering lights ^[4][9].
• Utility involvement: Contact your power company if neighbors are also affected or if you suspect a transformer/line issue ^[1][6].

Step-by-Step Guide to Diagnosing and Fixing Partial Power Loss

Immediate Troubleshooting Steps

Start by systematically ruling out simple fixes before assuming complex electrical failures. Safety is critical: avoid touching exposed wires, stand on a dry surface, and use a flashlight (not candles) if inspecting in low light.

• Check the circuit breaker panel:
• Open the panel and look for breakers in the "off" position or halfway between on/off (tripped). Reset any tripped breakers by flipping them fully to "off," then back to "on" ^[2][4].
• If a breaker trips immediately after resetting, unplug all devices on that circuit before attempting to reset it again—this indicates an overload or short circuit ^[9].
• Inspect for signs of damage: blackened breakers, burning smells, or warm panels suggest serious issues requiring an electrician ^[7].

• Reset GFCI outlets:
• GFCI (Ground Fault Circuit Interrupter) outlets—common in kitchens, bathrooms, and garages—can trip without affecting the breaker. Press the "reset" button on all GFCI outlets, even if they appear functional ^[2][8].
• If a GFCI won’t reset or trips repeatedly, it may be faulty or detecting a ground fault (e.g., water exposure or damaged wiring) ^[10].

• Test 240V appliances:
• Appliances like electric dryers, ranges, or water heaters run on 240V circuits, which require both hot legs to function. If these appliances are dead, the issue likely involves a lost hot leg or main breaker failure ^[3][7].
• If 240V appliances work but 120V outlets/lights don’t, the problem is isolated to one phase of your system ^[5].

• Assess external factors:
• Check if neighbors on the same transformer also have power issues. If so, contact your utility provider to report a potential transformer or line failure ^[1][6].
• Look for weather-related damage (e.g., fallen branches on power lines) or recent power surges that may have damaged equipment ^[4].

When to Call a Professional

If basic troubleshooting doesn’t restore power, the problem may involve hazardous conditions or utility-side failures. Contact a licensed electrician or your power company in these scenarios:

• Persistent tripping: A breaker or GFCI that repeatedly trips after resetting signals an underlying issue like a short circuit, overloaded wiring, or faulty appliance ^[9][2].
• Signs of electrical faults:
• Burning smells near outlets, switches, or the breaker panel ^[7].
• Sparking, buzzing sounds, or warm-to-the-touch wires/outlets ^[4].
• Flickering lights or intermittent power, which may indicate loose connections or a failing main breaker ^[8].
• Utility-side suspicions:
• No power to one phase (e.g., all 120V outlets on one side of the house are dead) but the main breaker is on. This suggests a lost hot leg, often caused by utility equipment failure ^[5][6].
• Visible damage to the meter, service entrance cables, or transformer (e.g., scorch marks, sagging lines) ^[1].
• No obvious cause: If all breakers/GFCIs are on, no appliances are overloading the system, and neighbors have power, the issue may involve hidden wiring faults or a failed main breaker ^[10][7].

Professional diagnostics may include:

• Testing voltage at the main panel to confirm a lost hot leg ^[5].
• Inspecting the meter base and service entrance for loose or corroded connections ^[7].
• Using thermal imaging to detect overheating wires or components ^[9].