HOW-TO GUIDE
Why Does Half My House Have No Power but the Breakers Look Fine?
By the OhmSavvy Research Team ·
Some symptoms mean stop and call now
- Lights flaring bright on some circuits and dim on others, electronics failing, or a burning smell from the panel or meter: switch off the main breaker if you can do so safely and call the utility. For smoke or fire, leave and call 911.
- A service drop that is sagging, sparking or down: stay well clear and call the utility's emergency line.
- Never remove the panel cover, pull the meter or touch the service entrance. Those parts stay live even with the main breaker off.
Two legs, one panel
The utility transformer delivers two hot conductors and a neutral. Each hot measures about 120 V to the neutral, and the two hots measure about 240 V to each other. Inside the panel the bus bars alternate, so one single-pole breaker sits on leg L1, the next on L2, and a two-pole breaker for a dryer or air conditioner straddles both. Nothing about a lost leg moves a breaker handle; the breakers simply have nothing to pass on.
That is why the outage looks random from inside the house. The kitchen counter might be dead while the fridge outlet works, or the upstairs bedrooms go dark while the hallway lights carry on, purely because of which slot each circuit was given when the panel was wired.
What is dead tells you why
| Symptom | Likely cause | What to check | Who should fix it |
|---|---|---|---|
| Many rooms dead, 240 V appliances dead or half-working | Lost leg: transformer fuse, service drop, meter or main | Neighbors; a 240 V receptacle with a meter | Utility first, then electrician |
| One circuit's outlets and lights dead | Breaker tripped but handle barely moved | Push that breaker firmly OFF, then ON | Homeowner; electrician if it fails |
| Bathroom, garage or outdoor outlets dead | GFCI tripped in a different room | TEST/RESET on every GFCI you can find | Homeowner |
| A run of outlets dead, earlier ones on the circuit fine | Failed connection at the last working outlet | Which outlet is the last live one | Electrician |
| Lights bright and dim, appliances acting strangely | Lost or loose neutral | Nothing; switch off the main if safe | Utility immediately |
| Outages come and go, often in wind or heat | Loose connection at the service or meter | Note times and weather | Utility, then electrician |
1Checks you can make safely
Start outside the house. Ask a neighbor on the same street whether they have power, and look for partial outages on their side too, since several homes often share one transformer. Then work through the panel and the protective devices you can reach without tools.
- Reset every breaker the hard way. A tripped breaker can sit only a few millimeters from ON. Push each handle firmly all the way to OFF and then back to ON; a tripped one will click and stay on. Some breakers also show a colored trip flag in a small window.
- Find the hidden GFCIs. A single GFCI in a bathroom can feed outlets in another bathroom, the garage and outside. Press RESET on each one. A GFCI breaker in the panel will have its own TEST button on the handle.
- Try the 240 V appliances. If the dryer tumbles without heat, the range has some elements working and others not, or the air conditioner hums without starting, a missing leg becomes very likely.
- Map the dead circuits. Note which breaker numbers are dead. Every other slot down one side, or alternate rows, matches a leg pattern; a single numbered circuit does not.
2Confirm a lost leg with a meter
A multimeter rated CAT III 600 V, with intact leads and finger guards, can confirm the diagnosis at a receptacle without anyone opening the panel. Wear safety glasses and keep your fingers behind the probe guards. First, put the probes in the hot and neutral slots of a working 120 V outlet, then in a dead one. A healthy outlet reads roughly 114 to 126 V, the band ANSI C84.1 treats as normal for 120 V service. A dead outlet on a lost leg usually reads 0 V, but not always.
The clearer test is at a dryer or range receptacle with the appliance unplugged. Measure from each hot slot to neutral, then between the two hots. Normally both hot-to-neutral readings are near 120 V and the hot-to-hot reading is near 240 V. With one leg lost, one hot reads normally, and the hot-to-hot reading falls to around 120 V or less.
Don't be surprised by odd in-between numbers on the dead leg, such as 30 or 70 V. Any 240 V load left switched on, like a water heater element, connects the two legs and can feed a weak, useless voltage back onto the dead side. A meter with a low-impedance (LoZ) mode loads the circuit slightly and helps tell this kind of induced or backfed voltage from a real supply. Either way, a reading well below 120 V on one leg is a supply fault, not a branch-circuit problem, and you should switch off large 240 V loads until it is fixed. Our guide to using a multimeter covers setting up AC voltage measurement if you are new to it.
When it is only one circuit
If the dead area is a single circuit and its breaker resets and holds, the fault is somewhere along that circuit. Outlets on a branch circuit are usually daisy-chained, so a failed connection at one outlet takes out everything after it. Older installations that used the push-in "backstab" holes on the back of receptacles are particularly prone to this. Find the last outlet that works and the first that doesn't; the problem is usually at one of those two boxes. Opening them and remaking connections is a job for an electrician, and a scorched or loose receptacle there also explains intermittent AFCI trips.
Also check for a wall switch that controls an outlet. Many living rooms have a half-switched receptacle for a lamp, and it is easy to mistake for a fault.
Utility or electrician?
Meters for checking household voltage
Hands-on tested. True RMS, CAT III 600V, with NCV built in for a quick live check.
LoZ mode for ghost voltages, CAT IV 600V / CAT III 1000V, True RMS.
Budget True RMS meter with NCV and a Live-wire test; maker's sources disagree on maximum voltage.
As an Amazon Associate I earn from qualifying purchases. Prices and availability are shown on Amazon.
Frequently asked questions
Why does my dryer spin but not heat when half the house is out?
Many electric dryers run the drum motor on 120 V from one leg and the heating element on 240 V across both. With one leg gone, the motor may still turn while the element gets nothing. A range or water heater can behave similarly. That combination is a strong sign of a lost service leg rather than a tripped breaker.
Can the main breaker cause half the house to lose power?
Yes. The main breaker is a two-pole device, and one pole can fail or develop a burnt connection while the handle still reads ON. Only a licensed electrician should test or replace it, and the utility may need to disconnect service first.
My lights are getting brighter and dimmer, not just going off. Is that the same thing?
No, and it is more urgent. Lights that brighten on some circuits while dimming on others usually mean the neutral connection has failed, which can push well above 120 V onto sensitive equipment. Switch off the main breaker if it is safe to reach and call the utility right away.
Will the power company charge me to check the service?
Policies vary by utility. Many check the transformer, service drop and meter at no charge, while repairs to equipment the homeowner owns, such as the meter base or service entrance cable on some homes, are the homeowner's responsibility. Ask when you call.
Can a storm or a falling branch cause half the house to lose power?
Yes. Wind, ice or a branch can break or loosen one conductor of the overhead service drop while the other stays connected, leaving one leg dead. Look for a sagging or damaged line between the pole and the house, but stay well clear of it. Call the utility's outage or emergency number, and never try to move or touch a downed line.
