Half the House Has No Power? Causes and What to Do in Phoenix

Why half the house has no power: the two legs

Most Phoenix homes get power through two hot conductors, often called legs, plus a neutral. Each leg is 120 volts to the neutral, and the two legs together give you 240 volts. Your panel splits the regular 120-volt circuits between the two legs, so roughly half the lights and outlets ride on each one. The big appliances, the AC condenser, an electric dryer, an electric range or water heater, a pool pump on 240 volts, use both legs at once.

So when one leg goes dead, you get exactly the strange pattern people describe:

• About half of the lights and outlets work and the other half don't, in no obvious room-by-room order.
• The AC, dryer or electric range won't run at all, or hums without starting.
• Some lights on the "dead" side may glow faintly. Power can leak back through 240-volt appliances into the dead leg, which makes the problem look even stranger.
• Every breaker still sits in the ON position, because nothing tripped.

That last point is why people get stuck. A breaker only trips when there's too much current. When a leg is lost, there's too little, so the panel gives you no clue.

Lost leg vs. loose neutral: know the difference

A lost leg means part of the house is dead. A loose or broken neutral at the service is different and more dangerous. Instead of going dark, lights get brighter in one room while they dim in another, and they swing when a big appliance starts. Electronics may shut off, reboot or fail, and bulbs can burn out early. That happens because, without a solid neutral, the voltage on each side of the house floats depending on what's turned on.

What causes a lost leg or a failing service connection

The problem can sit on the utility's side of the meter or on yours. The usual suspects:

• Utility side: a blown fuse or failed connection at the transformer, a damaged overhead drop after a monsoon storm, or a failed splice in an underground service line. Newer Valley subdivisions are often fed underground from a green pad-mounted transformer, while older neighborhoods may still have overhead lines.
• Meter socket: a jaw in the meter socket that has worn, loosened or burned. Heat from years of heavy summer AC loads makes this a common failure point in older Phoenix meter panels.
• Main breaker: a main breaker that has failed internally on one pole. It still looks ON, but one side isn't passing power.
• Service lugs and conductors: a loose, corroded or overheated connection where the service wires land, more common with older aluminum service conductors that were never re-torqued.
• A subpanel: if the dead area is one wing, a garage or a casita, a tripped or failed breaker feeding a subpanel can mimic a lost leg.

Who fixes what depends on where the failure is. Your utility generally owns the service up to the meter; the meter socket, main breaker and panel usually belong to the homeowner. Our post on who does what on a Phoenix service upgrade lays out that split in more detail.

Call the utility or an electrician?

Often both, and the order matters. Start with the utility, because they can check the transformer and the service line, and if the problem is on their side they're the only ones who can fix it. If you're an APS customer, the APS outage map shows known outages and lets you see whether your area is affected. SRP customers can report a partial outage through SRP's outage line or app.

If the utility tests their side and finds full voltage on both legs coming in, the problem is in your meter socket, main breaker or panel, and that's electrician work. Burned meter jaws and failed mains are licensed-electrician repairs, and in an older home they're often the moment to decide between a repair and a replacement. If the meter socket is part of an all-in-one unit, our post on meter-main combo replacement explains what that job involves, and our panel upgrade cost guide covers what drives the price if replacement makes sense.

Don't wait it out

It's tempting to live with half the house working for a few days, especially when the fridge is on the good side. We'd advise against it. A connection that has failed partway is often a connection that's overheating, and it can get worse under load. In a Phoenix summer, the AC is the first thing you lose, and running a compressor on bad voltage is hard on it. A loose neutral can damage electronics and appliances throughout the house. Get it diagnosed the same day if you can; this is what our emergency electrician service is for.

If it's only a few outlets in one area that went dead, that's a different problem with different causes. Start with our checklist for an outlet not working when the breaker isn't tripped. If your main breaker is tripping rather than staying on with half the power missing, see why the main breaker keeps tripping.

Half-house power loss in Peoria

In Peoria, we see both sides of this. Newer neighborhoods in north Peoria are mostly fed underground, so when a leg drops it's often a splice or a pad-mounted transformer issue for the utility. Older homes closer to Old Town Peoria have meter panels that have carried decades of 115-degree afternoons, and worn meter jaws and tired main breakers show up there. Monsoon season adds storm damage to overhead lines. Most Peoria homes are served by APS; check the name on your bill so you call the right utility.

What we check when half the house is out

• Voltage on both legs and the neutral at the meter and the main, to find out which side has the problem.
• The meter socket jaws and service connections for heat damage, looseness and corrosion.
• The main breaker, tested under load, not just by looking at the handle.
• Lugs, neutral bar and any subpanel feeders, re-tightened or repaired as needed.
• Whether a repair is the right fix, or the age and condition of the equipment make a panel upgrade the better long-term answer.

Lost power to half the house?

Call your utility first to rule out their side, then call us. Tell us what works, what doesn't and whether lights are dim or bright, and we'll tell you how urgent it is. B and D Electric LLC is licensed and bonded, Arizona ROC 361086, and our two owners have more than 40 years of combined experience. Call or text (480) 828-1181, or request an estimate.