If you see burn marks at your meter base, weatherhead, or service entrance, or smell something burning near the panel — do not touch the panel. Call us and your utility immediately: (916) 903-0277.

Partial Power Loss

Half the house
has no power

Some circuits work. Others are completely dead. No breakers have tripped — or the ones that have don’t account for everything that’s out. If individual breakers are also tripping alongside the partial loss, see Breaker Keeps Tripping for those circuits. This pattern is different from a single tripped breaker, and in most cases the cause is outside your home, not inside it. Here’s how to read the situation and who to call first.

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Check This First

Call your utility
before calling an electrician

Partial power loss where some circuits are dead and some are working — with no tripped breakers inside the panel — is most often caused by a problem at or before the meter. Your utility company can check that equipment without entering your home, and without a service charge.

Check if neighbors are affected

Step outside and ask neighbors if they have power, or check whether street lights and other visible utility infrastructure are operating. If multiple homes on your block have partial or full outages, the problem is almost certainly at the transformer or on the utility line — and the utility is already aware or will be once you call.

Call your utility and report it as an outage

Your electric utility — SMUD, Roseville Electric, or PG&E depending on your area — can check equipment at the transformer and at the meter from their side. Report the outage as “partial power loss” so the dispatch team knows to check both legs of your service. If they confirm voltage is normal at the meter, the problem shifts to the house-side equipment.

What a utility tech can check without coming inside

The utility is responsible for the transformer, the overhead or underground service drop to your home, and the meter itself. A utility technician can verify that both legs of your 240V service are present and at the correct voltage at the point where service enters your meter. They cannot check anything inside your panel.

Why This Happens

How split-phase service
creates partial loss

Understanding the basic structure of your electrical service explains why this type of outage produces the specific pattern you’re seeing.

Your home uses two voltage legs

Standard residential electrical service in the US is 240V split-phase. The utility delivers two 120V legs to your home, and your panel distributes them alternately across breaker positions. Breaker positions alternate between the two incoming service legs. If one leg is lost, circuits throughout the panel may go dead in a pattern while others stay energized — which is why the outage often doesn't follow room boundaries. Some breakers draw from both legs — those handle 240V appliances like HVAC equipment, electric dryers, and water heaters.

Losing one leg cuts half the circuits

When one utility leg fails — whether at the transformer, the service drop connection, the weatherhead, or the meter base — all the breakers on that leg go dead simultaneously. The result is a pattern where roughly half the circuits have no power, 240V appliances are completely dead, and the other half of the house continues operating normally. No breakers trip because the breakers aren’t the cause. When the neutral connection is degraded rather than a leg completely failed, the result may be flickering or voltage irregularity on working circuits rather than dead circuits — see Flickering Lights.

The house-side boundary

An electrician can work on the equipment inside your panel and at the service entrance — the weatherhead, mast, meter base, and main disconnect. Ownership and responsibility boundaries vary by utility and jurisdiction. The utility generally owns its meter and utility-side equipment, while the property owner typically owns the meter socket and service equipment. We can inspect the customer-owned equipment after the utility rules out a problem on its side. If the lost leg is at the utility’s connection point rather than at the weatherhead or service entrance, the fix is the utility’s responsibility, and no amount of work inside your panel will resolve it.

When an Electrician Can Help

House-side causes
and what we look for

If the utility confirms their service is delivering normally at your meter, the fault is on the house side. Here’s what that investigation involves.

Service entrance and weatherhead inspection

The service entrance is where the utility’s wires connect to your home’s wiring at the weatherhead and mast. These connections can loosen, corrode, or fail mechanically — particularly on older homes with aging equipment or after physical damage. We inspect the condition of the entrance conductors and connections at the top of the mast as far as is safely accessible.

Voltage measurement at the main panel

We measure voltage on both legs at the main lugs in the panel. This tells us whether both legs are arriving from the service entrance. If one leg reads near zero at the panel, the loss is between the meter and the panel — which is house-side equipment. If both legs read correctly at the panel but circuits on one leg are dead, the fault is within the panel wiring itself.

Main breaker and bus inspection

The main breaker can fail in ways that affect only one leg. Bus bar connections inside the panel can loosen or corrode over time, particularly at the breaker landing points. We inspect the panel for signs of heat at the bus, unusual voltage readings on individual breakers, and any physical damage or aging that could account for the loss on the affected circuits.

Recurring partial loss or aging service entrance equipment: if the service entrance equipment is old enough to be contributing to the problem, the long-term fix may involve a service entrance upgrade alongside any immediate repairs. See Exterior & Service Entrance.

Common Questions

Partial power loss
FAQ

Why do I have power in some rooms but not others?

The most common explanation when no breakers have tripped is a lost utility leg. Homes use a split-phase 240V service that delivers two separate 120V legs from the utility. Each leg feeds roughly half the circuits in your panel. When one leg fails at the utility connection, the meter, or the weatherhead, half the circuits go dead while the other half continue working. This pattern often indicates a utility-side or service-entrance problem rather than a normal branch-circuit issue, which is why the utility should usually be contacted first.

Should I call my utility company or an electrician first?

Call the utility first. Your electric utility — SMUD, Roseville Electric, or PG&E depending on your area — can check their equipment at the transformer, the service drop, and their connection at the meter without entering your home. If the utility confirms their service is delivering correctly at your meter and you’re still experiencing partial loss, that’s when we can investigate the house-side equipment — the service entrance, the main breaker, and the panel bus.

Can I check the panel myself if I have partial power loss?

You can open the panel door and look for tripped breakers without touching anything. If there are no signs of heat, moisture, burning, or damage, a tripped breaker may be reset once. If it trips again, leave it off and contact a licensed electrician. What you should not do is touch the main breaker terminals, the large wires entering the top of the panel, or any bus connections — those remain live even when the main breaker is off, because they carry utility voltage. If you see burn marks, melted components, or smell burning near the panel, leave it alone and call.

What does a lost utility leg look like in the house?

Some 120V circuits work normally while others are completely dead, with no tripped breakers. 240V appliances — HVAC, electric dryers, electric ranges, well pumps — are either completely dead or behaving abnormally, because they draw from both legs simultaneously. You may also notice lights at reduced brightness on the working side, since certain appliances can create backfeed effects through shared neutrals when one leg is lost.

Half the househas no power

Call your utilitybefore calling an electrician