HOW-TO GUIDE
Why Does a Circuit Breaker Keep Tripping?
By the OhmSavvy Research Team ·
Leave the panel itself to a licensed electrician
- Measuring load current at an outlet or with a clamp meter around an accessible cord is reasonable for most people — opening the panel is not, unless you're qualified.
- Don't repeatedly force-reset a breaker that trips quickly or immediately; that pattern means a real fault, not a nuisance trip.
- Disconnect suspect devices before testing rather than leaving them running while you investigate.
1The three reasons a breaker trips
| Cause | Typical pattern |
|---|---|
| Overload | Trips after a delay, once enough load accumulates on the circuit |
| Short circuit | Trips instantly, often the moment a specific device is plugged in or switched on |
| Ground fault (GFCI-specific) | Trips on current leaking to ground, even without an overload present |
2Measure the circuit's actual load
Clamp around a single conductor feeding the load while everything normally run on that circuit is switched on, and read the current. Clamping a whole power cord reads close to zero, because the equal and opposite currents in the hot and neutral wires cancel; plug the device through an AC line splitter (an adapter that separates one conductor into a loop for the clamp) instead of cutting or opening anything. Compare the total against the breaker's amperage rating printed on its handle.
A worked example shows where your clamp reading lands on that curve. A common 15 A, 120 V household circuit can carry 15 × 120 = 1,800 W before it reaches its rating, and electrical code guidance generally limits continuous loads to 80% of the rating, about 12 A or 1,440 W. A 1,500 W space heater (12.5 A) plus a 700 W microwave (about 5.8 A) on the same circuit totals roughly 18.3 A, about 1.2 times the rating: squarely in the thermal region, which is why that combination trips after a few minutes rather than the moment the microwave starts. A breaker that trips the instant a device is switched on is sitting at the far right of the curve, and that points to a short.
3Overload vs. a short or ground fault
If measured current is close to or exceeds the breaker's rating, you've likely found a genuine overload — reduce the load on that circuit or have a higher-capacity circuit installed by an electrician. If current measures well within the breaker's rating but it still trips, especially instantly, the problem is more likely a short or ground fault rather than overload, and needs an electrician's inspection.
Unplug everything, then add back one at a time
What you can check safely yourself
Measuring load current at an accessible point, checking what's plugged into the circuit, and inspecting cords and plugs for obvious damage are reasonable DIY checks. Opening the panel, testing inside it, or working on any wiring you're not confident handling safely should go to a licensed electrician.
Which meter to use
A clamp meter reads the circuit's real current without opening anything up. See the clamp meter buying guide.
Meters in our reviews
AC clamp current up to 400A — reads a circuit's real load directly.
For voltage checks alongside the current measurement.
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Frequently asked questions
How do I know if it's an overload rather than a fault?
An overloaded breaker usually takes a while to trip — minutes, not instantly — and trips consistently once a predictable combination of devices is running. A short circuit or ground fault typically trips the breaker immediately, often the instant a device is plugged in or switched on, with no gradual buildup.
Can I just add up the wattage of everything on the circuit to check for overload?
Yes, as a useful estimate: add up the rated watts of everything on the circuit, divide by your supply voltage to get amps, and compare against the breaker's rating — but actually measuring with a clamp meter while everything is running is more reliable, since name-plate ratings don't always reflect real-world draw.
Is it safe to just keep resetting the breaker and see if it holds?
Resetting once to see if it was a one-off nuisance trip is reasonable. A breaker that trips repeatedly, especially quickly or immediately, should not be reset repeatedly — that's a sign of a real fault, and continuing to force it closed risks the condition that's causing it.
Why does the breaker only trip when the weather is hot or humid?
Heat increases resistance and current draw in many devices (especially anything with a motor, like an AC unit), and breakers themselves can trip slightly more readily when warm since their trip mechanism is often temperature-sensitive by design. A seasonal pattern can be a genuine clue pointing toward a specific appliance or the breaker's own age and condition.
When should I call an electrician instead of troubleshooting further myself?
Call an electrician for anything requiring you to open the panel, any breaker that trips immediately and repeatedly, any sign of burning smell or scorch marks, or if you're not confident identifying and safely disconnecting the load causing the problem yourself.
