What Is an Electrical Panel?
An electrical panel (also called a load center, breaker box, or service panel) is the main distribution point for electrical circuits in a building. It receives power from the utility through the service entrance and distributes it to individual branch circuits protected by circuit breakers or fuses.
Modern panels range from 100 to 400 amps. Most single-family homes have 150-200 amp service. The panel's amperage rating should match or exceed the main breaker size.
Critical Safety Defects
Some electrical panel issues create immediate safety hazards. These findings typically warrant repair before closing or significant price negotiation.
Double-Tapped Breakers
A double-tapped breaker has two wires connected to a single terminal designed for one wire. This is the most common electrical panel defect found during home inspections.
Why it matters: Single-pole terminals aren't designed to secure two wires properly. Loose connections create resistance, which causes heat buildup. Heat damages insulation and can ignite nearby materials.
The fix: Install a tandem breaker (if the panel allows), add a new breaker for the second circuit, or install a sub-panel. Cost ranges from $100-500 depending on the solution.
Exception: Some breakers are designed for double-tap connections. These have special terminals rated for two conductors, indicated on the breaker or panel labeling.
Missing Knockouts and Open Gaps
Knockouts are the circular metal pieces removed to run cables into the panel. Missing knockouts leave openings that allow pests, debris, and fingers to contact live electrical components.
The National Electrical Code requires all panel openings to be sealed. Knockout fillers cost under $1 each and take seconds to install. This is a minor fix but indicates sloppy work that may exist elsewhere.
Melted or Burned Components
Any sign of heat damage inside an electrical panel indicates a serious problem. Melted plastic, burn marks on bus bars, or charred wire insulation all point to overcurrent events or arcing that the breakers failed to stop.
Heat damage requires immediate evaluation by a licensed electrician. The cause must be identified and corrected. Damaged components must be replaced. In some cases, the entire panel needs replacement.
Improper Wiring Connections
Common wiring defects include:
- Aluminum wiring connected to copper-only terminals
- Wire gauge too small for the breaker amperage
- Multiple neutrals on a single bus bar terminal
- Loose connections visible without touching wires
- White wires used as hot conductors without proper marking
These issues range from code violations to fire hazards. Each requires professional correction.
Problem Panel Brands
Certain electrical panel brands have documented safety issues. Insurance companies may refuse coverage or require replacement of these panels.
Federal Pacific Electric (FPE) Stab-Lok Panels
Federal Pacific Electric panels, particularly those with Stab-Lok breakers manufactured from the 1950s through 1980s, have a well-documented history of breaker failure. Multiple studies found that FPE breakers fail to trip under overcurrent conditions at rates far exceeding industry standards.
The Consumer Product Safety Commission investigated FPE panels but never issued a formal recall. However, many electricians and home inspectors recommend replacement based on the documented failure rates.
Identifying FPE panels: Look for "Federal Pacific Electric" or "FPE" on the panel door or interior labeling. Stab-Lok breakers have a distinctive red or orange stripe.
Replacement cost: $1,500-3,000 for a comparable new panel.
Zinsco and Sylvania-Zinsco Panels
Zinsco panels were manufactured from the 1970s through the early 1980s. The breakers can melt to the bus bar, preventing them from tripping during overcurrent conditions.
When breakers fuse to bus bars, they become permanently energized. The circuit has no overcurrent protection. This creates serious fire risk.
Zinsco panels often have colored breaker handles (pink, blue, green). The Sylvania-Zinsco name appears on some panels after Sylvania acquired the company.
Pushmatic Panels
Pushmatic panels use push-button breakers rather than toggle switches. While not as problematic as FPE or Zinsco, these panels have their own issues:
- Breakers are difficult to find for repairs
- The push-button design makes it hard to tell if a breaker is tripped
- Some units have inadequate bus bar connections
Pushmatic panels aren't necessarily dangerous, but parts availability and age often make replacement practical.
Fuse Panels
Fuse panels themselves aren't defective, but they have limitations:
- Fuses must be replaced after tripping (breakers reset)
- Wrong-size fuses can be easily installed
- Most fuse panels are 60-100 amp, undersized for modern needs
- Insurance companies may charge higher premiums
When fuses are properly sized and the panel has adequate capacity, there's no inherent safety problem. But many buyers replace fuse panels for convenience and insurance purposes.
Panel Capacity Issues
Panel capacity affects both safety and functionality. Undersized panels may be unable to handle modern electrical loads.
Understanding Panel Amperage
Panel amperage indicates maximum capacity:
- 60 amp: Minimal for small homes, no central AC or electric appliances
- 100 amp: Adequate for smaller homes without heavy loads
- 150 amp: Standard for average homes
- 200 amp: Standard for larger homes or those with heavy loads
- 400 amp: Large homes or those with workshops, pools, EV charging
According to the National Electrical Code, service capacity should match connected load with appropriate demand factors. A 60-amp panel serving a home with central AC, electric dryer, and electric range is undersized.
Signs of Inadequate Capacity
Indicators that a panel may be undersized:
- Breakers trip frequently during normal use
- No available spaces for additional circuits
- Tandem breakers used excessively
- Extension cords used as permanent wiring
- Lights dim when appliances cycle on
Panel upgrades typically cost $1,500-4,000 and may require utility coordination for service entrance upgrades.
Moisture and Corrosion
Water and electricity don't mix. Moisture inside electrical panels creates multiple hazards.
Sources of Panel Moisture
Common causes of water in electrical panels:
- Roof leaks above panel location
- Service entrance cable allowing water intrusion
- Exterior panels with failed weatherproofing
- Condensation from temperature differentials
- Flooding or plumbing leaks
Outdoor panels have weatherproof enclosures, but seals degrade over time. Any gap allows water entry.
Effects of Moisture Damage
Water in electrical panels causes:
- Rust on bus bars and breaker contacts
- Corrosion that increases resistance
- Degraded insulation on conductors
- Short circuits and ground faults
- Breaker malfunction
Rusty panels need professional evaluation. Minor surface rust may be acceptable if the source is eliminated and components remain functional. Significant corrosion typically requires panel replacement.
Code Violations vs. Safety Hazards
Not every code violation is a safety hazard. Understanding the difference helps prioritize concerns.
Grandfathering and Existing Installations
Electrical codes aren't retroactive. Panels installed to code at the time of construction aren't automatically defective when codes change. This concept is called grandfathering.
However, some conditions are hazardous regardless of when the work was done. FPE panels were defective even when new. Double-tapped breakers violate manufacturer specifications, not just codes.
When Updates Are Required
Major renovations, additions, or service upgrades typically trigger requirements to bring the electrical system up to current code. Minor repairs usually don't require full upgrades.
Local jurisdictions vary on requirements. Some are strict about compliance during property sales. Others have no point-of-sale electrical requirements. Your real estate agent or home inspector can advise on local practices.
Related Terms
Key electrical terminology that appears in inspection reports:
- Bus bar: Metal strip inside the panel that distributes power to breakers
- Service entrance: Point where utility power enters the building
- Branch circuit: Individual circuit serving outlets, lights, or appliances
- Overcurrent protection: Breakers or fuses that stop current flow when limits are exceeded
- Bonding: Connecting metal components to ensure electrical continuity
- Grounding: Connecting the electrical system to earth for safety
- Tandem breaker: Two breakers in a single slot (where permitted)
- AFCI: Arc-Fault Circuit Interrupter, required in bedrooms and living areas by current code