How to Choose the Right Panelboard for Your Commercial Project (Cost + Sizing Tips)
Choosing the right panelboard for your commercial project is crucial for safety, efficiency, and cost-effectiveness. Whether you’re upgrading an existing system or installing a new one, selecting the correct panelboard ensures reliable power distribution and compliance with electrical codes.

In this guide, we’ll cover:
✔ Key factors in selecting a commercial panelboard
✔ How to size a panelboard correctly
✔ Cost considerations and budgeting tips
✔ Common mistakes to avoid
Let’s dive in!
1. Understanding Panelboards and Their Role in Commercial Buildings
What Is a Panelboard?
A panelboard is a critical component of an electrical distribution system, housing circuit breakers or fuses that control power flow to different circuits in a building.
Why Choosing the Right Panelboard Matters
- Safety: Prevents overloads and electrical fires.
- Efficiency: Ensures optimal power distribution.
- Compliance: Meets NEC (National Electrical Code) requirements.
- Scalability: Allows for future expansions.
2. Key Factors to Consider When Choosing a Panelboard
A. Electrical Load Requirements
Before selecting a panelboard, calculate your building’s total electrical load. Consider:
- Lighting
- HVAC systems
- Office equipment
- Industrial machinery (if applicable)
Pro Tip: Hire an electrical engineer for precise load calculations.
B. Panelboard Types: Main Breaker vs. Main Lug
- Main Breaker Panelboards: Include a built-in main disconnect switch for added safety.
- Main Lug Panelboards: No main breaker; used as subpanels fed from a main panel.
C. Voltage and Phase Requirements
- 120/240V Single-Phase: Common for small businesses.
- 208V or 480V Three-Phase: Ideal for large commercial or industrial facilities.
D. Number of Circuits Needed
Estimate the number of circuits required based on:
- Current needs
- Future expansions
E. Space and Mounting Options
- Indoor vs. Outdoor: Weatherproof enclosures for outdoor use.
- Flush vs. Surface Mount: Depends on wall space and aesthetics.
3. How to Size a Panelboard for Your Commercial Project
Step 1: Calculate Total Electrical Load
Add up the wattage of all connected devices and apply the 80% rule (NEC requirement) to avoid overloading.
Formula:
Total Load (Amps) = Total Wattage / Voltage
Step 2: Determine Panelboard Amperage Rating
Choose a panelboard with a capacity 20-25% higher than your calculated load for safety.
Step 3: Account for Future Expansion
Select a panelboard with extra slots for additional circuits.
4. Cost Breakdown: How Much Does a Commercial Panelboard Cost?
Panelboard Type | Average Cost (USD) |
---|---|
100-Amp Main Breaker Panel | $200 – $500 |
200-Amp Main Breaker Panel | $500 – $1,200 |
400-Amp Three-Phase Panel | $1,500 – $3,500 |
Custom/Industrial Panelboards | $4,000+ |
Additional Costs:
- Installation labor ($1,000 – $5,000)
- Permits and inspections ($200 – $800)
5. Common Mistakes to Avoid When Choosing a Panelboard
❌ Underestimating Load Capacity → Leads to tripped breakers and system failures.
❌ Ignoring Future Expansion → Requires costly upgrades later.
❌ Choosing the Wrong Enclosure Type → Outdoor panels need weatherproofing.
❌ Skipping Professional Help → Improper sizing can violate NEC codes.
6. Final Tips for Selecting the Best Panelboard
✔ Consult an electrician for accurate load calculations.
✔ Prioritize safety features like surge protection and GFCI breakers.
✔ Compare brands (Siemens, Square D, Eaton) for reliability.
✔ Plan for future growth to avoid frequent upgrades.
Conclusion
Choosing the right panelboard for your commercial project ensures safety, efficiency, and compliance. By considering load requirements, sizing correctly, and budgeting wisely, you can avoid costly mistakes and ensure a reliable electrical system.
Need help selecting the best panelboard? Contact an electrical expert today!