Entire subpanel appears dead
Every circuit fed from that subpanel is out, including lights and receptacles in the same area.
Start here: Start at the main panel and find the feeder breaker that supplies the subpanel.
Electrical
Breaker Subpanel Dead
Direct answer: A dead subpanel usually means the feeder breaker in the main panel tripped, the subpanel lost one or both incoming hot legs, or the whole area is actually on a larger upstream outage. Treat it as a high-risk electrical problem, because a loose feeder can look like a simple reset issue right before it overheats.
Most likely: Most often, the main panel breaker feeding the subpanel is tripped or half-tripped, or a nearby GFCI or outage is making it seem like the whole subpanel is dead.
First figure out whether the entire subpanel is dead, only some circuits are out, or one side of the subpanel lost power. That split matters. Reality check: a bad breaker is not the first assumption here. Common wrong move: resetting every breaker repeatedly without checking for heat, smell, or a half-tripped feeder in the main panel.
Don’t start with: Do not pull the subpanel cover, tighten lugs, or replace breakers just to see what happens.
If the subpanel serves a garage, shed, basement, or addition,check whether lights, receptacles, and any 240-volt loads all died at the same time.
If only part of the subpanel is dead,suspect a lost leg or loose feeder connection and stop sooner than you would for a simple branch-circuit outage.
Last reviewed: 2026-04-05
What the dead subpanel looks like
Only half the subpanel seems dead
Some breakers still run loads, but others do nothing, or a 240-volt load stopped while a few 120-volt circuits still work.
Start here: Treat this like a lost leg or loose feeder warning, not a routine breaker reset.
Subpanel died after using one tool or appliance
Power dropped right after a heater, compressor, welder, EV charger, or similar heavy load started.
Start here: Unplug or switch off that load before checking the feeder breaker.
Subpanel is dead after storm or outage
The area lost power after weather, utility work, or a blink, and the subpanel never came back normally.
Start here: Confirm whether the main service and nearby homes are fully back on before touching panel breakers.
Most likely causes
1. Main panel feeder breaker tripped or is sitting half-tripped
That is the most common clean failure when a whole subpanel goes dark, especially after a heavy load or short on one of its circuits.
Quick check: At the main panel, look for the breaker feeding the subpanel. If the handle is not firmly in ON, switch it fully OFF first, then back ON once.
2. Upstream outage or GFCI is making the problem look bigger than it is
Garage, basement, exterior, and outbuilding areas often have one dead feed point that makes several circuits seem dead at once.
Quick check: See whether the main panel still has normal power and reset any obvious tripped GFCI devices serving the area.
3. One feeder leg is lost from a failed connection or damaged breaker connection
When only one side of the subpanel works, or 240-volt loads died while a few 120-volt circuits still run, one incoming hot leg may be missing.
Quick check: Do not open the panel. Note whether every other breaker position seems dead or whether only one side of the room still has power, then stop and call an electrician.
4. Loose, overheated, or water-damaged subpanel feed connection
Buzzing, heat, a hot breaker, discoloration, rust, or moisture around either panel points to a dangerous connection problem, not a simple reset.
Quick check: Without removing covers, look for scorch marks, melted plastic smell, rust streaks, or water near the panel and stop if you find any.
Step-by-step fix
Step 1: Confirm it is really the subpanel and not just one dead circuit
A single tripped branch breaker, dead GFCI, or switched receptacle can make a whole area feel dead when the subpanel itself is fine.
- Check two or three different loads served by the subpanel, not just one outlet or one light.
- If the area has GFCI receptacles, press TEST and then RESET on any that are accessible and dry.
- See whether any 240-volt equipment on that subpanel is also dead, if you have any.
- Look at the main house panel and confirm the rest of the home still has normal power.
Next move: If one GFCI or one branch circuit was the real problem, the subpanel is not dead. Troubleshoot that individual circuit instead. If everything on that subpanel is still out, move to the feeder breaker check.
What to conclude: You are separating a local circuit problem from a true subpanel feed problem.
Stop if:
- You find water inside or around any receptacle or panel area.
- A GFCI will not reset and feels warm, smells burnt, or trips instantly again.
- You hear buzzing, crackling, or see flickering at the panel.
Step 2: Find and reset the feeder breaker in the main panel once
The feeder breaker that supplies the subpanel is the safest common check and the most likely fix when the whole subpanel went dead suddenly.
- At the main panel, identify the breaker labeled for the garage, shed, basement, addition, or subpanel.
- If the handle looks centered or not fully ON, switch it firmly all the way OFF first.
- Then switch it back ON once with a deliberate motion.
- If a large load was running on the dead subpanel, leave that load unplugged or switched off for now.
Next move: If the subpanel comes back and stays on with normal loads, a temporary overload or short may have tripped the feeder. If the feeder breaker will not reset, trips immediately, or the subpanel stays dead, do not keep cycling it.
What to conclude: A one-time successful reset points to an overload or downstream fault. A breaker that will not hold points to a live fault or a feeder problem that needs more than a reset.
Stop if:
- The feeder breaker feels hot to the touch at the handle or panel cover area.
- You see arcing, hear snapping, or smell burning when trying to reset it.
- The breaker trips immediately more than once.
Step 3: Check whether the failure is total or only one side of the subpanel
A subpanel with one dead leg is a different and more dangerous problem than a simple full trip. It often shows up as half the circuits dead or odd 120/240 behavior.
- Make a quick list of what still works and what does not on that subpanel.
- Notice whether every other breaker position seems dead, or whether only some lights and receptacles still work.
- If a 240-volt load on that subpanel is dead while a few 120-volt loads still run, treat that as a lost-leg clue.
- Do not remove the deadfront or test inside the panel unless you are a qualified electrician.
Next move: If you confirm the whole subpanel is either fully on or fully off after a clean reset, the issue is more likely a tripped feeder or downstream overload. If only part of the subpanel works, stop DIY and call an electrician.
Stop if:
- Only half the circuits work.
- Lights are unusually dim on some circuits and bright on others.
- Any 240-volt equipment lost power while some 120-volt circuits still operate.
Step 4: Look for outside clues of heat, moisture, or physical damage
You can often spot a dangerous feeder problem without opening anything. Those clues matter more than guessing at a bad breaker.
- Check around both the main panel and subpanel for rust, water stains, damp walls, or signs of condensation.
- Smell near the panel covers for a hot plastic or burnt insulation odor.
- Look for discoloration at breaker openings, warped trim, or soot around the panel door.
- If the subpanel is in an outbuilding, think about recent leaks, rodent activity, impact damage, or trench work near the feeder path.
Next move: If you find no damage and the feeder reset restored power, monitor the panel and reduce heavy simultaneous loads until the cause is clearer. If you find any heat, burning smell, moisture, corrosion, or physical damage, leave the feeder off and call an electrician.
Stop if:
- There is any sign of water entering the panel.
- You smell burning even with the breaker off.
- The panel cover is warm, stained, or discolored.
Step 5: Leave the feeder off and get the right help when the signs point past a simple reset
Once a subpanel stays dead, loses one leg, or shows heat or moisture, the next safe move is professional diagnosis at the feeder breaker, lugs, conductors, and panel interior.
- Turn off large loads on the dead subpanel if you can do so without opening panels.
- If the feeder breaker reset did not hold, leave it OFF.
- Write down exactly what happened: full outage, half outage, storm event, heavy load, smell, heat, or repeated tripping.
- Call a licensed electrician and report whether the whole subpanel is dead or only one side is dead.
A good result: If the electrician finds a loose feeder, damaged breaker connection, water intrusion, or failed panel component, that repair should be done before the subpanel is used again.
If not: If utility-side power is unstable or the main service is also affected, contact the utility after the electrician rules that in.
What to conclude: The safe finish here is not more homeowner testing. It is isolating the feed and getting the feeder and panel checked under controlled conditions.
FAQ
Why is my subpanel dead but the main panel still has power?
Usually the breaker feeding the subpanel tripped in the main panel, or the subpanel lost one or both incoming hot legs. A local GFCI or outage in that area can also make it seem like the whole subpanel is dead.
Can a bad breaker cause a dead subpanel?
Yes, but it is not the first thing to assume. A tripped feeder, downstream short, loose feeder connection, water intrusion, or lost leg is more important to rule out first. On panel work, the danger is the connection problem behind the symptom.
What does it mean if only half the subpanel works?
That is a strong lost-leg warning. Some 120-volt circuits may still run while others are dead, and 240-volt loads usually stop working. Stop there and call an electrician, because a loose or failed feeder connection can overheat.
Is it safe to reset the feeder breaker once?
One deliberate reset is reasonable if there is no heat, smell, buzzing, water, or visible damage. If it will not hold, trips again, or anything seems hot or burnt, leave it off and stop.
Should I open the subpanel and tighten connections myself?
No. Tightening feeder lugs or working inside a live panel is not a basic homeowner repair. The incoming conductors can remain dangerous even when branch breakers are off, and a loose connection can fail violently if handled wrong.
Could a storm or utility problem make the subpanel look dead?
Yes. If the main service is unstable, one leg from the utility is missing, or power only partly returned after an outage, the subpanel can act dead or half-dead. If the main panel also shows odd behavior, involve the utility after an electrician checks the house side.