Wiring a breaker is a job for a licensed electrician in most places
You should not wire a breaker into your breaker box yourself. Most states and municipalities require a licensed electrician to do this work, and many insurance policies will not cover damage or injury from unlicensed electrical work inside the main panel. Even if local code does not forbid it, the risk of electrocution, fire, or damage to your home's electrical system is high enough that the cost of hiring a professional is worth it.
If you are considering this work because an electrician's quote seems expensive, get a second quote. If you are considering it because you want to understand what the electrician is doing, this guide explains the process so you can follow along and ask informed questions.
Key Takeaways
- Wiring a breaker into the main panel requires a licensed electrician in most jurisdictions, and homeowner attempts can void insurance and create fire or electrocution hazards.
- The main panel stays energized even when the main breaker is off, so the risk of fatal shock is present throughout the job.
- A licensed electrician will turn off the main breaker, test that power is off, run the wire from the panel to the location where the new circuit will serve, and find the breaker in an available slot.
- The cost of hiring a professional electrician for this work is typically $150 to $300 per breaker, depending on your region and the complexity of the circuit.
- If your breaker box has no empty slots, you will need a sub-panel or a tandem breaker, both of which also require a licensed electrician.
Why the main panel is dangerous even when the main breaker is off
The main breaker controls power to the rest of the panel, but the utility lines that feed the main breaker remain live. This means the top of the main breaker, the bus bars it connects to, and the area around the meter are always energized, even after you flip the main breaker to off. A slip of a tool, a moment of inattention, or wet hands can result in a fatal shock.
A licensed electrician has training in how to work safely in this environment and carries insurance that covers the work. A homeowner does not. Many fire departments and electrical inspectors have seen house fires that started because someone without training made a mistake in the main panel.
What a licensed electrician does when wiring a new breaker
The electrician will first visit your home to understand where the new circuit needs to go and what it will power. They will then obtain any required permits from your local building department. In some jurisdictions, the permit is issued before the work; in others, the inspector comes after.
At the panel, the electrician will turn off the main breaker and use a non-contact voltage tester to confirm that the panel is de-energized. They will then run the new wire from the panel to the location where the circuit will serve — for example, from the panel to a new outlet in the garage. The wire size depends on the breaker size: a 15-amp breaker uses 14-gauge wire, a 20-amp breaker uses 12-gauge wire, and larger breakers use thicker wire.
Once the wire is in place, the electrician returns to the panel, turns the main breaker back on, and installs the new breaker in an available slot. The breaker snaps into place on the bus bar. The hot wire (usually black or red) connects to the breaker terminal, and the neutral wire (white) and ground wire (bare copper or green) connect to their respective bus bars in the panel. The electrician then tests the circuit to confirm it works and that the breaker trips when it should.
The cost of hiring an electrician for this work
A licensed electrician typically charges between $150 and $300 to wire a single breaker into an existing panel, depending on your region, the time of day, and whether a permit is required. Some electricians charge a flat rate per breaker; others charge an hourly rate plus materials. If the job requires running wire through walls or conduit, the cost will be higher.
If you need multiple breakers installed, ask the electrician for a discount on the per-breaker rate. Some electricians will install three or four breakers in one visit for less than the cost of three or four separate visits.
What to do if your breaker box has no empty slots
If every slot in your panel is full, you have two options: install a sub-panel or replace some of your existing breakers with tandem breakers.
A sub-panel is a smaller electrical panel that connects to a new breaker in your main panel. It gives you additional slots for new breakers. A sub-panel costs more to install than a single breaker because it requires running heavier wire from the main panel and mounting the sub-panel on a wall. However, it is the better choice if you need many new circuits.
A tandem breaker is a breaker that takes up one slot but controls two circuits. Not all panels accept tandem breakers, and not all breaker manufacturers make them for every panel model. Your electrician will know whether tandem breakers are an option for your panel. If they are, installing a tandem breaker costs about the same as installing a standard breaker.
Permits and inspections
Most jurisdictions require a permit before a new breaker is installed. The permit ensures that the work is done by a licensed electrician and that it meets local electrical code. The cost of a permit is usually $25 to $75, and the electrician will handle obtaining it.
After the work is complete, a building inspector will visit your home to confirm that the breaker and the circuit it controls meet code. The inspector will check that the wire size matches the breaker size, that the wire is properly secured, and that the breaker is correctly installed in the panel. If everything passes, you will receive a permit sign-off, and the work is complete.
Signs that you need a new circuit
You may need a new circuit if you frequently trip a breaker when using multiple appliances on the same circuit, if you want to add a new outlet or appliance in a location far from existing outlets, or if you are upgrading to a larger electrical service. A licensed electrician can assess your home's electrical system and recommend whether a new circuit is necessary.
Do not add outlets to an existing circuit by daisy-chaining power strips or extension cords. This creates a fire hazard and does not solve the underlying problem of insufficient capacity. A new circuit is the safe solution.
Frequently Asked Questions
Can I install a breaker myself if my local code allows it?
Even if local code permits homeowner work in the main panel, your homeowner's insurance may not cover damage or injury that results. Before attempting this work, contact your insurance company and ask whether unlicensed work in the main panel is covered. Most insurers will say no.
What happens if I wire a breaker incorrectly?
An incorrectly wired breaker can cause a fire, electrocution, or damage to appliances on that circuit. The breaker may not trip when it should, leaving the circuit unprotected. An electrical inspector will catch the mistake during inspection and require you to hire a licensed electrician to fix it.
How long does it take an electrician to wire a breaker?
Wiring a single breaker into an existing panel usually takes one to two hours, depending on how far the wire must run and whether the electrician needs to drill through walls or run conduit. If multiple breakers are being installed in the same visit, the time per breaker decreases.
Do I need to turn off power to the whole house before the electrician arrives?
No. The electrician will turn off the main breaker when they are ready to work in the panel. You should make sure the electrician has access to the breaker box and that the area around it is clear of clutter.
What is the difference between a 15-amp and 20-amp breaker?
A 15-amp breaker is rated for circuits that draw up to 15 amps and uses 14-gauge wire. A 20-amp breaker is rated for up to 20 amps and uses 12-gauge wire. The thicker wire in a 20-amp circuit can handle more current without overheating. Use the breaker size that matches the wire gauge and the load the circuit will carry.