When a whole house goes dark, the cause is usually somewhere outside it and the whole street knows about it. When half the house goes dark and half carries on as though nothing happened, the cause is almost always one identifiable failure — and the first useful question is which side of the meter it sits on.
Why a house has halves
A typical home service arrives as two energized conductors and a neutral. The circuits in the panel are divided between those two legs, roughly evenly, which is why a failure on one leg takes out a scattered-looking set of rooms rather than a tidy half of the floor plan.
Anything that runs on 240 volts — range, dryer, water heater, air handler, well pump — uses both legs at once. So when one leg is lost, those appliances are the loudest symptom. They do nothing, or they hum, or they run badly, while the lights in the next room are perfectly normal.
That pattern is the diagnosis. A scattered set of dead circuits plus a large appliance that will not start is a lost leg, not a coincidence of failures.
The tell that decides who to call
A leg can be lost on either side of the meter, and the fix belongs to different people depending on which.
Start with the neighbors. If the houses either side are also behaving oddly, the fault is upstream — a utility conductor or a transformer — and it belongs to the power company. Most of this area is served by Florida Power & Light, though a few cities including Homestead and Lake Worth Beach run their own electric utilities, so check who bills you before you report it.
If your property is the only one affected, the fault is more likely on your side: the service entrance, the main breaker, a main lug connection, or the panel itself. That is an electrician's work. It can still be the service drop to your house alone, which is the utility's, so a report to both is not wasted effort.
The version that damages things while you decide
There is a specific failure worth recognizing, because it does harm quietly while everything still appears to work: a lost or loose neutral.
With the neutral compromised, the two legs stop being held at a stable voltage relative to each other. Instead they float against the load. The signs are distinctive:
- Lights unusually bright in one part of the house and dim in another.
- Brightness that shifts when a large appliance switches on or off.
- Electronics failing in ones and twos over a few days for no obvious reason.
- A faint flicker across the house in time with the air conditioning.
What is happening is that lightly loaded circuits get pushed well above their normal voltage while heavily loaded ones sag. Equipment on the high side is being cooked. This is the one on this page that should not wait, and if you can safely switch the main breaker off, doing so protects everything still plugged in. Treat it as an emergency call rather than a scheduled repair.
What you can check safely
- Ask two neighbors whether anything is off at their end.
- Look at the main breaker. If it has tripped, one reset attempt is reasonable. If it will not hold, leave it.
- Check whether a 240-volt appliance will start. That confirms a lost leg faster than counting dead outlets.
- Write down which rooms are dead. It saves real time when someone arrives.
What not to do: do not remove the panel cover, and do not touch the meter or anything on the utility side of it. The main lugs inside a panel stay energized when the main breaker is off, which is the part that surprises people.
Why it is worth chasing rather than living with
Partial power is easy to tolerate. Half the house works, the router is on, and the missing half feels like something to deal with later. The problem is that most causes of a lost leg are connections that are failing rather than failed — a corroded lug, a loose termination, a conductor damaged where it enters the building. Those generate heat at the point of failure, and heat inside a panel or a service entrance is how this stops being an inconvenience.
Salt air accelerates every one of those. If the house has original service equipment and sits anywhere near the water, this is worth looking at properly rather than waiting to see whether it settles down.
If part of the house is out now
Note which rooms are dead, whether any 240-volt appliance runs, and whether the neighbors are affected. Those three answers get most of the way to the cause before anyone opens anything.
Tell us what the system is doing and we will tell you what it needs — send us the details, or call (305) 359-7312. We work across Miami-Dade, Broward and Palm Beach.
