What are Distribution Panels and How Do They Work?
Distribution panels, also known as panelboards or distribution boards, are key components of electrical distribution systems that divide an electrical power feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure. These panels serve as critical junction points in the electrical system, distributing power from the main service entrance to various branch circuits throughout a building or facility.
Distribution panels work by receiving power from a main breaker or larger feeder circuit and distributing that power through multiple smaller circuit breakers or fuses to individual branch circuits. The internal bus bars conduct electricity from the main power source to the individual circuit protection devices, which in turn feed the connected loads. When a fault occurs on any circuit, the corresponding protective device trips, isolating only the affected circuit while maintaining power to the rest of the system.
Key components of distribution panels include:
- Enclosure: Metal cabinet that houses all internal components and provides physical protection
- Main Lugs or Main Breaker: Connection point for incoming power supply
- Bus Bars: Copper or aluminum conductors that distribute power to individual circuits
- Circuit Breakers or Fuses: Protective devices for individual branch circuits
- Neutral Bar: Common connection point for neutral conductors
- Ground Bar: Connection point for equipment grounding conductors
- Directory: Labeling system identifying the purpose of each circuit
- Trim or Cover: Provides access to breakers while covering live parts
Uses and Applications
Distribution panels serve essential functions across various settings:
Residential Applications
- Main distribution panels in homes
- Sub-panels for additions, workshops, or garages
- Service entrance equipment in multi-dwelling units
- Load centers for specialized circuits (HVAC, appliances)
- Distribution for auxiliary buildings or outdoor areas
Commercial and Institutional Buildings
- Floor-level power distribution
- Dedicated systems for lighting circuits
- Power distribution for office equipment
- HVAC and mechanical systems power
- Emergency and standby power distribution
- Sub-distribution for tenant spaces in commercial buildings
Industrial Applications
- Power distribution for manufacturing equipment
- Control power distribution
- Process area sub-distribution
- Dedicated systems for critical equipment
- Lighting and utility power distribution
- Harmonic mitigating panels for sensitive electronic loads
Important Considerations Before Buying Used Distribution Panels
Usage and Maintenance History
Understanding the operational history provides insights into equipment condition:
- Verify age and original installation environment
- Check for evidence of overheating or electrical faults
- Inspect bus bars for discoloration, pitting, or corrosion
- Verify insulation integrity throughout the panel
- Check mechanical operation of circuit breakers
- Look for signs of water damage or excessive dust contamination
- Review maintenance records if available
- Verify panel has not been subjected to fault currents beyond rating
Specifications and Compatibility
Ensure the panel meets your system requirements:
- Voltage rating must match your system (120/240V, 208/120V, 480/277V)
- Ampacity rating sufficient for your load requirements
- Available interrupt capacity (AIC) adequate for your location
- Number and type of circuit spaces meets your needs
- Bus configuration (phase arrangement, neutral position)
- Enclosure type suitable for environment (NEMA rating)
- Panel dimensions compatible with installation space
- Feed configuration (top/bottom/side) matches conduit arrangement
- Circuit breaker types compatible with your requirements
Purpose and Application
Select a panel appropriate for your specific needs:
- Main panel vs. sub-panel requirements
- Indoor vs. outdoor installation location
- Environmental conditions (temperature, humidity, dust)
- Accessibility requirements for maintenance
- Future expansion needs (spare capacity)
- Special requirements (surge protection, metering)
- Code compliance for specific applications
- Compatibility with existing equipment
- Specific grounding requirements
How Much Should I Budget for Distribution Panels?
Pricing varies significantly based on size, features, and condition:
New Distribution Panels
- Residential load centers (100-200A): $200-$600
- Small commercial panels (225-400A): $800-$2,500
- Medium commercial/industrial panels (400-800A): $2,000-$6,000
- Large distribution panels (800-1200A): $5,000-$15,000
- Specialty panels (healthcare, data center): 25-40% premium
- Panels with integrated surge protection: 15-25% premium
Used/Reconditioned Distribution Panels
- Typically 40-70% of new pricing depending on age and condition
- Fully refurbished panels with warranty: 60-75% of new cost
- As-is condition: 30-50% of new cost
- Testing and inspection costs: $200-$1,000 depending on size
- Replacement breakers (if needed): $50-$500 each depending on type
- Installation costs: $500-$3,000 depending on complexity
Cost Factors to Consider
- Age: Panels under 10 years typically command higher prices
- Manufacturer: Premium brands maintain higher resale value
- Condition: Evidence of good maintenance increases value
- Obsolescence: Availability of compatible breakers affects value
- Modifications needed: Adapting to specific requirements
- Code compliance: Updates needed to meet current standards
- Transportation: Shipping costs for larger units
- Documentation: Original labels and directories add value
When purchasing used distribution panels, thorough inspection by a qualified electrician is essential to ensure safety and reliability. The condition of the bus bars, insulation, and circuit breakers significantly impacts the panel's functionality and longevity. Special attention should be paid to signs of overheating, loose connections, or damaged components. While used panels can offer substantial savings, the critical role they play in electrical safety makes proper evaluation particularly important. Consider having used panels cleaned, inspected, and tested before installation to ensure they meet current electrical code requirements.