Breaker Panel (Load Center)

What is a breaker panel?

A breaker panel is the central hub of your home’s electrical system. Power from the utility meter enters the panel and is divided into individual circuits, each protected by a circuit breaker. These breakers automatically trip during overloads or short circuits to prevent overheated wires and fires. The panel also includes a main breaker that can shut off power to the entire home.

How it works

Inside the cabinet, two energized “hot” buses supply 120/240-volt split-phase power. Breakers snap onto these buses and feed branch circuits to outlets, lights, and appliances. A neutral bar returns current from 120-volt loads, and a ground bar connects equipment grounding conductors for fault clearing. In a main service panel, the neutral is bonded to the cabinet (ground). In subpanels, neutrals and grounds must be isolated from each other to keep normal current off grounding conductors.

Modern panels use thermal-magnetic breakers that sense both gradual overloads and sudden faults. Specialized breakers—AFCI (arc-fault) and GFCI (ground-fault), or dual-function breakers—provide added protection required by current electrical codes in many areas of the home.

Common uses and DIY applications

Adding new household circuits during permitted remodels (e.g., a new laundry, kitchen, or workshop circuit)
Installing a subpanel for a garage, basement, addition, or backyard office
Upgrading the service to support high-demand loads like EV chargers, heat pumps, hot tubs, or electric ranges
Troubleshooting a tripped breaker and safely resetting it after addressing the cause

Note: Work inside a live panel is hazardous and often requires permits. Many tasks should be left to a licensed electrician.

Types and variations

Main breaker panel: Has a large main disconnect that shuts off power to all branch circuits. Common ratings: 100A, 150A, 200A, 400A.
Main lug only (MLO) panel: No main breaker; fed from an upstream disconnect. Often used as subpanels.
Subpanel: A secondary panel fed from the main panel to add circuits in another area. Grounds and neutrals must be separated in subpanels, and the grounding electrode bond is at the service only.
Indoor vs. outdoor: Outdoor panels are rain-tight and rated for weather exposure. Indoor panels require a dry location with clear working space.
Bus material: Copper buses tend to have better conductivity and corrosion resistance; aluminum buses are common and cost-effective when properly listed and installed.
Breaker types:
- Single-pole (120V) for general lighting/receptacles
- Two-pole (240V) for large appliances (range, dryer, AC, EV charger)
- Tandem (two breakers that fit one space) only where the panel labeling allows
- AFCI, GFCI, or dual-function breakers for added protection as required by local code
Panel capacity: Stated in amps (service size) and spaces (number of breaker slots). A typical modern home uses a 200A, 30–40 space panel.

Selecting a breaker panel

Match your service size: Choose a panel rated for your service (e.g., 200A). Consider future projects like an EV charger or heat pump.
Plan for space: Pick a model with more spaces than you currently need to avoid tandem breakers later. Space for a whole-home surge protector is a plus.
Compatibility: Breakers must be listed for the panel brand and model. Using off-brand lookalikes can be unsafe and void listings.
Code-driven protection: If you’re remodeling, you may need combination AFCI and/or GFCI protection on certain circuits. Check local requirements.
Location and clearance: Panels need working space—typically at least 30 inches wide, 36 inches deep, and 6.5 feet high with a clear floor area—and should not be in closets or bathrooms. Local codes govern exact rules.
Quality features: Look for solid bus construction, clear labeling, copper or aluminum buses with listed lugs, and a hinged dead front that’s easy to remove. Factory-installed ground bars and labeling for tandem breakers are helpful.

Safe use and basic maintenance

Label circuits clearly: A well-labeled directory speeds up troubleshooting and emergency shutoffs.
Reset breakers correctly: After addressing the cause, move the handle fully to OFF, then to ON. Frequent tripping signals a problem.
Keep it dry and accessible: Don’t store items in front of the panel. Fix leaks, condensation, or rust immediately.
Periodic checks (visual only): Look for scorching, corrosion, buzzing, or loose cover screws. If you notice heat or a burning smell, call an electrician.
Test protection devices: Use the test button on GFCI/AFCI breakers per manufacturer guidance.
Leave internal work to pros: Removing the dead front exposes live parts, often even with the main breaker off. Hire a licensed electrician for torque checks, breaker replacements, subpanel wiring, service upgrades, or any work inside the cabinet.
Whole-home surge protection: Consider a listed surge protective device (SPD) at the panel to protect electronics and appliances.

Common mistakes to avoid

Oversizing breakers: A 20A breaker needs 12 AWG copper (or properly rated aluminum). Using a larger breaker than the wire allows is a fire hazard.
Double-lugging neutrals: Most panels require one neutral per terminal. Never stack neutrals on a single screw unless the label allows it.
Bonding errors in subpanels: In a subpanel, neutrals must be isolated from grounds; remove the bonding strap/screw unless the instructions say otherwise.
Tandem misuse: Only install tandem breakers where the panel label indicates. Overcrowding can overheat the bus.
Mixing aluminum and copper without listed lugs: Use lugs rated AL/CU and apply antioxidant compound as specified by the manufacturer for aluminum conductors.
Open knockouts: Unfilled holes invite pests and moisture; use listed knockout seals and proper cable clamps.
Ignoring recalled or problem panels: Consider replacement if you have certain older brands/models with known issues, such as some Federal Pacific Electric (FPE) Stab-Lok or Zinsco/Sylvania panels. Consult a licensed electrician.
Poor environment: Avoid installing in damp locations without proper enclosures; rust and corrosion degrade safety.

Related terms

Service drop/service lateral: The utility conductors feeding your meter and panel.
Meter-main combo: A unit that combines the meter socket and main breaker.
Branch circuit: Wiring from the breaker to outlets, lights, or equipment.
Feeder: Conductors supplying a subpanel from the main panel.
Bus bar: The metal bars distributing power inside the panel.
AFCI/GFCI/Dual-function breaker: Specialized protection against arc faults and ground faults.
Grounding electrode system: Ground rods or other electrodes bonded to the service equipment.

Practical examples

Kitchen remodel: You add dedicated 20A small-appliance circuits and a separate 240V breaker for an electric range. AFCI/GFCI protection and additional spaces in the panel keep the project compliant and organized.
Garage subpanel: A 60A feeder supplies a subpanel in the garage for tools and a mini-split. Neutrals and grounds are isolated in the subpanel, and the garage gets its own neatly labeled circuits.
EV charger: A 240V, 40A circuit requires panel capacity and space. If the main panel is full, a subpanel or a panel upgrade to 200A may be planned after a load calculation.
Basement finish: Multiple new lighting and receptacle circuits with AFCI/GFCI protection are added. Careful labeling and balancing of loads across both legs improve performance and reduce nuisance tripping.

A well-chosen, properly installed breaker panel improves reliability and safety, supports future upgrades, and makes troubleshooting far easier. For anything beyond basic operation and labeling, partner with a licensed electrician and follow local codes and manufacturer instructions.