Losing power in part of a house while the rest carries on is a more specific symptom than it appears. The pattern of what died and what survived usually identifies the cause before anyone measures anything, and the reason is in how a house is supplied.
Why a house has halves in the first place
A typical residential service arrives as two energised conductors — two legs — plus a neutral. Each leg supplies roughly half the breakers in the panel at around 120 volts. Appliances needing 240 volts, such as a range, a dryer, a water heater or an air conditioning compressor, use both legs together through a double-width breaker.
So “half the house has no power” is often a literal description of what has happened: one leg has been lost, and everything fed from it is dead while everything on the other leg is unaffected. That is why the failure looks so oddly selective, with rooms interleaved rather than neatly divided — the split follows the panel layout, not the floor plan.
The things worth checking before calling anyone
Look at the breakers, cover on. A tripped breaker usually sits in a middle position rather than fully off. If several are tripped at once, that is itself informative.
Check whether it is really half. Walk the house and note precisely what works. A whole floor, or a set of rooms with no obvious relationship, points at a leg. One room or one run of outlets points at a single circuit, which is a different and much smaller problem.
Check the GFCI outlets. A tripped GFCI kills everything downstream of it, which can be more outlets than people expect, often across more than one room. Bathrooms, garages, kitchens and outdoor outlets are where to look, and the reset button is on the device itself.
Look outside if you can do so safely. Are neighbours affected? Is anything visibly wrong at the overhead service — a branch on the conductors, a cable pulled away from the house? Look; do not touch, and do not get close to anything down.
The most common real cause: a lost leg
One of the two legs is no longer delivering power, and the break can be anywhere along it: at the utility connection, in the service conductors, at the meter, at the main breaker, or on the bus inside the panel.
Connections at the service carry the entire load of half a house and live through years of thermal cycling and, on an overhead service, weather. They loosen and corrode, and a corroding connection generates heat before it fails completely. Which is why this symptom is sometimes preceded for weeks by flickering, dimming, or lights brightening in one part of the house while dimming in another — all signs of a degrading service connection that has now gone the rest of the way.
A main breaker that has partly failed
The main breaker switches both legs together, and it can fail on one side while continuing to work on the other. From outside, the result is indistinguishable from a lost leg upstream: the breaker looks normal, is in the on position, and half the panel is dead.
Main breakers are also the component most likely to have been operated least and stressed most. Distinguishing a failed main from an upstream problem is a measurement at the panel, which is squarely electrician work, and it is the reason a definitive answer usually needs a visit rather than a phone call.
When the problem is not yours
A lost leg can just as easily originate on the supply side, particularly after weather. The clue is usually outside: if neighbours are affected, or if there is visible damage to the overhead service, it is a utility matter and reporting it is the fastest route to power.
The dividing line is the point where the utility's equipment meets yours. Their side is theirs to repair; from there into the house is an electrician's. In practice a utility crew attending will say which side the fault is on, and if it is the house side you will need an electrician before they can restore. Lawton-area homes are not all served by the same provider, so check which one covers your address before reporting.
If it is one area rather than half
A single room, or a run of outlets along one wall, is a circuit problem rather than a service problem — and the most common cause is a loose connection at a device partway along the run. Outlets are frequently wired in sequence, so a failed termination at one kills everything after it while leaving everything before it working.
That case is device and termination work, and it is worth checking whether the last working outlet in the sequence is warm or discoloured, because that is very often where the fault is.
The appliance clue that confirms it
Here is the detail that makes this symptom identifiable. Because 240 volt appliances use both legs, losing one leg makes them behave strangely rather than simply stopping. An electric range may have working lights and controls but no heat. A dryer may tumble but not heat, since the motor runs on one leg and the element needs both. An air conditioner may hum without starting.
So if some 120 volt circuits work, others are dead, and your 240 volt appliances are half-working rather than off, that combination points strongly at a lost leg. It is worth noting before you call, because it is exactly the information that shortens the diagnosis — and worth knowing that running motors on a lost leg can damage them, so switch them off.
What an electrician does
Measurement, working backwards. Voltage on each leg at the panel establishes immediately whether a leg is missing and whether the break is upstream or downstream of the main. From there it is a matter of following it: the main breaker, the terminations at the panel, the meter, and the service conductors.
Repairs range from re-terminating a connection to replacing the main breaker to service work involving the utility. What matters is the inspection that comes with it, because a connection that overheated has usually damaged what is around it, and a service that has degraded once at one termination has often done so at others. Where the panel itself is old, full or obsolete, this is frequently the point at which replacing it becomes the sensible answer rather than repairing one part of it.
Do not leave this one. A partly lost service means connections carrying current through resistance they were not designed for, and the failure mode is heat at the service equipment. If there is any smell, buzzing or warmth at the panel or meter, it is urgent rather than scheduled.