How to Replace the Main Electrical Panel in Your Commercial Building

Replacing the main electrical panel in a commercial building is a complex project that requires careful planning and execution. As the owner of the building, I walk through the key steps I took to successfully upgrade the outdated electrical system in my office complex.

Why Replace the Main Electrical Panel?

There were several reasons I decided to take on this major upgrade:

• Safety: The old fuse box was outdated and potentially dangerous. Breakers are safer and more reliable than fuses.

• Capacity: Our company was expanding and the old 100 amp panel could no longer handle the electrical load. We upgraded to 200 amps.

• Reliability: The old system was prone to tripping, leading to disruptions. A new panel provides steady, reliable power.

• Energy efficiency: New breakers and wiring increase efficiency. I expected to see energy savings after the upgrade.

Hiring an Electrical Contractor

Completing electrical work on a commercial property always requires hiring a licensed professional. I researched contractors and received three quotes.

Key factors in choosing a contractor:

• Licensure and years of experience
• Examples of past commercial panel upgrades
• Better Business Bureau rating
• Competitive pricing
• Availability to start immediately

I selected Smith Electric because they were highly recommended and insured, with fair pricing.

Selecting the Right Electrical Panel

The contractor and I worked together to select the ideal panel for my building's needs:

• Main breaker amperage: Chose 200 amp to handle expanded power demand

• Phases: Upgraded from single phase to three phase for more efficiency

• Number of breaker spaces: Chose 42 slots, leaving room for future growth

• Copper bus bars: More durable and energy efficient than aluminum

• Brand/Quality: Went with a Square D QO Premium Panel for proven reliability

Preparing the Project Site

Before starting demolition, the contractor and I took steps to prepare:

• Shut off main power to the building

• Disconnect all wires, conduits and equipment from old panel

• Coordinate with tenants to schedule planned power outages

• Provide temporary lighting and power where needed

• Protect sensitive equipment like computers

• Clear space around panel to allow workers room

Proper planning prevented business disruptions and protected equipment.

Removing the Old Panel

With power disconnected, the contractor was ready to remove the outdated main breaker panel:

• Disconnect ALL wires first for safety

• Inspect condition of surrounding wall/infrastructure

• Check for asbestos or other hazardous materials - have removed if found

• Demo old panel and conduit with care not to damage building

• Clean area to prepare for new panel installation

Removal went smoothly after thorough pre-inspection and wire disconnections.

Installing the New Panel

It was finally time to upgrade to the new Square D QO 200 amp panel:

• Mount new panel securely to wall, level and plumb

• Make wire holes through wall into panel box

• Run fresh conduit from panel to existing wires, if needed

• Connect all circuits carefully matching old configuration

• Label all breakers clearly

• Test operation thoroughly before re-energizing

With the heavy prep work done, the new panel was functional within a day.

Passing Final Electrical Inspection

Before signing off on the project, the local building department needed to:

• Verify licensed electrician completed the work

• Check panel amperage meets code

• Confirm proper circuit breaker types for application

• Test operation of main and branch circuits

• Check for neutral-to-ground separation

• InspectConnections, grounding and labeling

The new panel passed inspection with no issues. Permits were signed off.

Lessons Learned

Upgrading the main electrical panel went smoothly thanks to:

• Careful planning and contractor selection

• Proper safety procedures

• Oversizing the panel for extra capacity

• High-quality equipment from reputable brands

• Taking time to neatly organize and label all circuits

• Close coordination with building and fire inspectors

The project was a success and I'm glad I invested to update to a safer, more robust electrical system.