No, you should not replace a 15 amp breaker with a 20 amp breaker unless the wiring on that circuit has been upgraded to handle 20 amps
A circuit breaker's amperage rating must match the wire gauge it protects. A 15 amp breaker protects 14-gauge wire. A 20 amp breaker protects 12-gauge wire. If you install a 20 amp breaker on 14-gauge wire, the breaker will allow more current to flow through wire that cannot safely handle it. The wire will overheat, the insulation can melt, and an electrical fire can start inside your walls where you cannot see it.
The breaker's job is to trip before the wire gets damaged. When you increase the breaker size without upgrading the wire, you remove that protection. This is one of the most common electrical code violations in older homes, and it is dangerous.
Key Takeaways
- A 15 amp breaker on 14-gauge wire and a 20 amp breaker on 12-gauge wire are not interchangeable—the wire gauge must match the breaker rating.
- Installing a larger breaker on undersized wire bypasses the breaker's safety function and creates a fire hazard.
- If you need more power on a circuit, the correct fix is to run new 12-gauge wire from the panel and install a 20 amp breaker—not to swap the breaker alone.
- Electrical work in the main panel requires a licensed electrician in most jurisdictions; this is not a DIY repair.
- A circuit that trips frequently may need a larger breaker, but only if the wire has already been upgraded or if you upgrade it first.
Why wire gauge and breaker size must match
Electrical current generates heat as it moves through wire. Thicker wire (lower gauge number) can handle more current safely. A 14-gauge wire is rated for 15 amps maximum. A 12-gauge wire is rated for 20 amps maximum. These are not suggestions—they are the limits set by the National Electrical Code based on how much heat the insulation can withstand.
When current exceeds the wire's rating, the insulation begins to degrade. This happens slowly and invisibly inside walls. Eventually the insulation fails, bare wire touches a stud or another wire, and an arc starts. The breaker does not trip because the breaker is set to allow that current level. The arc continues until something burns.
The breaker is your safety net. Its amperage rating tells it when to trip and cut power. If you set the breaker higher than the wire can handle, you have cut the net.
When a circuit breaker trips and what it means
A breaker trips when current on that circuit exceeds its rating for a sustained period. A 15 amp breaker trips around 15 amps; a 20 amp breaker trips around 20 amps. If your 15 amp breaker trips frequently, it usually means one of three things: the circuit is genuinely overloaded, there is a short circuit, or the breaker itself is failing.
Overload is the most common cause. You are running too many devices at once on that circuit. The solution is not to install a bigger breaker—it is to move some devices to another circuit or to have an electrician run a new circuit for the high-demand appliance.
A short circuit or ground fault is less common but more serious. If the breaker trips when ready when you turn something on, or if it trips when nothing is plugged in, call an electrician. Do not try to solve this by upgrading the breaker.
How to upgrade a circuit from 15 amps to 20 amps safely
If you genuinely need a 20 amp circuit—for example, to power a dedicated appliance or to reduce overload on a crowded circuit—the correct procedure is to upgrade the entire circuit, not just the breaker. This means running new 12-gauge wire from the breaker panel to the outlets, and installing a new 20 amp breaker in the panel.
This is not a task for a homeowner. Working inside the main electrical panel requires a licensed electrician in most states and municipalities. The panel contains live electricity even when the main breaker is off, and mistakes can be fatal. Your electrician will also verify that your panel has capacity for a new breaker and that the circuit layout makes sense for your home's load.
The cost varies by region and by how far the new wire must run, but expect to pay several hundred dollars for a licensed electrician to run a new circuit and install a breaker. This is money well spent compared to the cost of an electrical fire.
What happens if you ignore this and install a 20 amp breaker anyway
In the short term, nothing visible happens. The circuit works. Lights turn on, outlets deliver power. You might think the problem is solved.
Over weeks or months, the 14-gauge wire on that circuit carries more current than it is designed to handle. The insulation heats up and becomes brittle. If the wire is bundled with other wires in a wall or conduit, the heat cannot escape easily and the temperature rises faster. Eventually the insulation cracks or melts. Bare copper touches something conductive—a nail, another wire, a metal stud—and an arc begins.
An electrical arc inside a wall does not trip the breaker because the breaker is set to allow that current level. The arc continues to burn, heating the wood and insulation around it. This can take hours or days. By the time you smell smoke or see flames, the fire is already well established inside the wall.
How to tell what wire gauge is in your walls
You cannot see the wire gauge from an outlet. You have to look at the breaker panel or trace the wire back to where it enters the wall. At the breaker panel, look at the breaker itself—it should be labeled with its amperage (15 or 20). Then look at the wire connected to that breaker. If the wire looks noticeably thicker than the wires on other breakers, it is likely 12-gauge. If it looks the same thickness as the wires on 15 amp breakers, it is likely 14-gauge.
The most reliable way is to have an electrician inspect the panel and the circuit. They can confirm the wire gauge, check the breaker, and tell you whether the circuit can safely be upgraded or whether you need a new circuit instead.
Older homes and code violations
Many homes built before the 1980s have 14-gauge wire throughout, with 15 amp breakers. As homes accumulated more appliances and devices, some homeowners or unlicensed electricians swapped in 20 amp breakers to stop the tripping. This is a code violation and a fire hazard, but it is common enough that home inspectors flag it regularly.
If you buy a home and find 20 amp breakers on what appears to be 14-gauge wire, do not assume the previous owner knew what they were doing. Have an electrician verify the wire gauge. If it is indeed 14-gauge, the breaker should be downgraded to 15 amps, or the wire should be upgraded to 12-gauge and the breaker left at 20 amps. Either way, it needs to be corrected.
Frequently Asked Questions
What if I only need a little more power on that circuit?
The breaker does not have a "little more" setting. It is either rated for 15 amps or 20 amps. If the wire is 14-gauge, it must have a 15 amp breaker, period. If you need more power, move some devices to another circuit or have a new circuit installed.
Can I replace the breaker myself if I turn off the main breaker first?
No. The main breaker does not de-energize the panel itself—only the circuits downstream. The bus bars and the connections to the utility lines remain live. Touching them can cause electrocution or arc flash. This work requires a licensed electrician.
What if the breaker is just old and needs replacing?
If the breaker itself is failing—tripping without an overload, or not tripping when it should—it does need to be replaced. But it should be replaced with the same amperage rating. A licensed electrician can test the breaker and confirm whether it is faulty or whether the circuit is genuinely overloaded.
Is it ever okay to use a 20 amp breaker on 14-gauge wire?
No. There is no exception. The wire gauge and breaker rating must match. If someone tells you otherwise, they are wrong and creating a fire hazard.
How much does it cost to upgrade a circuit?
The cost depends on how far the new wire must run, whether walls need to be opened, and your region's labor rates. A short run might cost $300 to $500. A longer run or one that requires opening walls could cost $800 or more. Get quotes from licensed electricians in your area.