Why Is My House Having Half the Power Out?
Reviewed 2026-07-30 · How we research
Quick answer: half the power out
Half your power going out usually means you've lost one of the two 120V legs coming from the utility transformer, while the other leg still feeds some circuits. This is different from a tripped main breaker and can damage 240V appliances like your AC or dryer if left unaddressed. Call your utility provider and an electrician right away.
Urgent — act now
Losing power to roughly half the house — while the other half works fine — often points to a lost utility phase, which can damage 240V appliances within minutes. Call your utility and an electrician immediately.
US homes receive standard split-phase 240V service: two 120V hot legs and a neutral. Circuits are split between the two legs at the panel, which is why losing one leg kills roughly half your outlets and lights while the other half stays lit — it's often confused with a random partial outage but has a specific, identifiable cause.
This matters because 240V appliances like your AC condenser, electric dryer, and range depend on both legs simultaneously. A lost leg can deliver unbalanced voltage to these appliances that damages compressors and motors within minutes of continued operation.
Warning signs of half the power out
- Roughly half the outlets and lights in the house are dead while others work normally
- 240V appliances like the AC, dryer, or range don't run at all or run erratically
- Neighbors on the same transformer are also experiencing partial outages
- Lights that do work seem unusually dim or unusually bright
- A burning smell or buzzing accompanies the outage at the meter or panel
Most likely causes of half the power out, ranked
1. A lost utility leg (open neutral or blown fuse on the transformer)
Most common cause of a clean half-house outage
Split-phase service delivers two 120V legs from the utility transformer to your panel, and circuits are alternated between them breaker by breaker. If one leg fails — from a blown fuse cutout at the transformer, a broken utility connection, or storm damage to the service drop — every circuit wired to that leg goes dark while the other leg's circuits stay lit, producing a clean half-and-half pattern.
10-minute self-test: Check whether outages follow a predictable pattern room to room rather than being random, and call your utility to ask if others nearby are also reporting partial outages.
This cause is not a DIY repair — it needs a licensed electrician and utility company.
2. A lost or open neutral connection
Common and can cause voltage damage
If the shared neutral wire from the utility connection loosens or breaks, voltage on the two legs becomes unbalanced instead of a clean loss — some circuits may get less than 120V while others spike above it, sometimes visible as lights that are unusually dim on one side and unusually bright on the other rather than fully dead.
10-minute self-test: Check whether the lights that stay on seem noticeably brighter than normal rather than just being unaffected — this points toward a neutral problem rather than a simple lost leg.
This cause is not a DIY repair — it needs a licensed electrician and utility company.
3. A failed main breaker or bus bar connection in the panel
Less common but possible in panels 25+ years old
Inside the panel, one of the two hot bus bars can develop a loose or corroded connection at the main breaker lugs, cutting off every circuit breaker seated on that bus while the other bus continues functioning normally — visually indistinguishable from a lost utility leg until an electrician checks voltage at the panel itself.
10-minute self-test: This cannot be safely diagnosed from outside the panel; note whether the outage started with any unusual sound (a pop or buzz) from the panel area.
This cause is not a DIY repair — it needs a licensed electrician and utility company.
4. A tripped or failed subpanel feed
Common in homes with a detached garage or finished basement addition
If circuits in one section of the house — an addition, basement, or garage — are all fed from a subpanel rather than the main panel, a tripped subpanel breaker or a failed feeder cable will take out everything downstream of that subpanel while the rest of the house on the main panel stays completely normal.
10-minute self-test: Check whether the dead circuits are all in one physical area of the house fed by a subpanel, and check that subpanel for a tripped main breaker.
Your 10-minute check list for half the power out
- Map which specific rooms and outlets are affected to see if there's a physical or wiring pattern
- Check if 240V appliances (AC, dryer, range) are affected — this points to a lost leg or neutral issue
- Check any subpanel in a garage, basement or addition for a tripped main breaker
- Call your utility to ask about outages or transformer issues in your immediate area
What it costs to fix half the power out
| Cause / repair | DIY cost | Professional cost |
|---|---|---|
| Utility service call for a lost leg | $0 | Usually free — utility-side repair |
| Electrician diagnostic and panel inspection | $0 | $150–$300 |
| Main breaker or bus bar repair | not realistic | $400–$1,200 |
| Subpanel feeder cable repair | not realistic | $500–$1,800 |
| Service entrance / weatherhead repair | n/a | $600–$2,000 |
See the full cost breakdown for this repair →
DIY fixes for half the power out
Unplug 240V appliances immediately
Disconnect or shut off the breaker for your AC condenser, electric dryer, and range as soon as you suspect a lost leg or open neutral, since unbalanced voltage can damage their motors and compressors within minutes.
Call your utility before calling an electrician
If the cause is on the utility's side of the meter — a blown transformer fuse or damaged service drop — only the utility can restore it, and doing so is free. An electrician can't fix what's outside their scope.
Mistakes to avoid with half the power out
- Never run 240V appliances while suspecting a lost leg or open neutral
- Don't assume it's just 'the power company's problem' without checking your own panel and subpanels too
- Do not repeatedly flip breakers trying to restore power without understanding the cause first
Where homeowners waste money on half the power out
- Replacing individual outlets or breakers before confirming whether the fault is upstream at the utility service
- Paying an electrician for panel work when the fault turns out to be the utility transformer, which they cannot repair
When to call a licensed electrician and utility company about half the power out
An electrician will measure voltage between each hot leg and neutral at the panel — 0V on one leg confirms a lost utility connection, while an imbalance (like 90V and 150V) points to a lost neutral instead.
If 240V appliances were running during the event, most electricians recommend having them checked for winding damage before returning them to service.
What a licensed electrician and utility company actually does on this job →
How to prevent half the power out coming back
- Have your service entrance and meter connections inspected if your home is over 25 years old
- Ask an electrician to torque-check panel bus connections during any electrical inspection
- Consider a whole-house surge protector, which can also help detect and limit damage from voltage imbalance events
Why Is My House Having Half the Power Out — questions homeowners ask
Why do only some of my outlets have power?
US homes split circuits across two 120V hot legs from the utility transformer. Losing one leg kills every circuit wired to it while the other leg's circuits stay on, creating a clean half-house pattern.
Is a lost leg dangerous to my appliances?
Yes. 240V appliances like your AC and dryer need both legs simultaneously; an imbalance or loss can send incorrect voltage to their motors and cause damage within minutes if they keep trying to run.
Who fixes a lost utility leg, me or an electrician?
If the fault is at the transformer, fuse cutout, or service drop, only your utility company can repair it, and this service is typically free. An electrician handles anything from the meter inward.
How can I tell if it's my panel or the utility's fault?
Call your utility first — if neighbors are also affected or a lineman confirms an issue at the transformer, it's utility-side. If you're the only one affected and the utility finds nothing, an electrician needs to check your panel and service entrance.
Problems related to half the power out
- Why Is My House Having a Breaker That Keeps Tripping?Often shows up alongside this problem. Your breaker keeps tripping because the circuit is drawing more current than its rating, or a short/ground fault is pulling current outside the wire.Electrical, Lighting & Power Get it inspected
- Why Is My House Having Warm Electrical Outlets?Often shows up alongside this problem. Warm outlets are almost always caused by a loose wire connection or an overloaded circuit generating resistive heat.Electrical, Lighting & Power Urgent — act now
- Why Is My House Getting a Burning Electrical Smell?Often shows up alongside this problem. A burning electrical smell is caused by overheating insulation, an overloaded circuit, or an arcing connection reaching temperatures high enough to scorch plastic.Electrical, Lighting & Power Urgent — act now
- Why Is My House AC Not Turning On?An AC that won't turn on at all is most often a thermostat issue, a tripped breaker, or a safety switch — the HVAC disconnect, a float switch from a full condensate pan, or a limit switch from a dirty filter.Heating, Cooling & Air Urgent — act now
Sources used for half the power out
- NEC Article 230 — Services
- Institute of Electrical and Electronics Engineers (IEEE) — Split-Phase Distribution Standards
- Consumer Product Safety Commission — Electrical Safety Guidelines