Replacing a broken electrical panel in a commercial building is a complex and potentially dangerous project that should only be attempted by a licensed electrician. As the property owner or facility manager, it is crucial to understand the full process in order to properly plan, budget for, and oversee the repair work. In this article, I will provide an in-depth guide on the key steps involved in replacing a faulty electrical panel in a commercial setting.
Gather Background Information on the Existing Electrical System
Before beginning any work, it is essential to thoroughly research the existing electrical system. This includes:
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Consulting building plans and permits - Review all available documentation on the existing electrical system, including the original building plans and any permits for subsequent electrical work. This provides insight on the overall system design and components.
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Inspecting the electrical panel - Visually inspect the current panel to determine the make and model, voltage and amperage rating, number of phases, and type (circuit breaker or fuse). Also note any signs of damage or malfunction.
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Identifying connected loads - Make a list of all electrical loads powered by the panel, such as lighting, outlets, HVAC systems, security systems, fire alarms, etc. Understanding the circuit load is vital for specifying the new panel.
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Checking power supply - Verify the power supply feeding the faulty panel, including voltage, amperage capacity, and wiring gauge size. Check for any problems with the supply wiring or terminations.
Select an Appropriate Replacement Electrical Panel
With a firm understanding of the existing system, the next key step is selecting a suitable replacement panel.
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The new panel must match the voltage (120/240V single phase or 120/208V three phase) and amperage capacity of the old panel. Allow for some future growth in capacity.
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Choose circuit breakers or fuses to match the existing electrical system. Fuses are still commonly used in some older commercial buildings.
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Verify that the new panel can accommodate the required number of circuits or circuit positions. Count each individual branch circuit in the old panel.
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Choose a reputable, commercial-grade panel that meets all electrical codes and standards. Cutler Hammer, Square D, and Siemens are quality brands.
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Select appropriate panel accessories like main disconnects, subfed breakers, and surge protective devices.
Safely De-Energize the Panel and Circuitry
Before any removal work begins, the panel and all connected circuitry must be completely de-energized to avoid electrocution and arc flashes:
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Locate the panel's main circuit breaker or disconnect switch and shut it off to de-energize the branch circuits.
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For panels fed with multiple hot wires, also locate the upstream breaker or disconnect and shut off the live power supply.
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Use a multimeter to double-check that all incoming hot wires, bus bars, and circuit breakers have been fully de-energized before touching any wiring.
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Once de-energized, lock out and tag out the main breaker or disconnect switch with a warning placard.
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Where possible, de-energize large electrical equipment loads (like motors) by manually switching them off verses relying on circuit breakers.
Remove the Faulty Electrical Panel
With the old panel safely powered down, the next stage is cautious removal:
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Disconnect all wiring from the faulty panel, including the incoming power feed and all circuit wiring. Note wire locations for proper reconnection.
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If surface mounted, unbolt the panel from the wall. For a recessed panel, remove cover plate screws and pull it out.
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Cut the old panel free from the wall without damaging the existing cabling. A reciprocating saw or angle grinder (with proper PPE) can make cuts around sticky panels.
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Cap and label all disconnected wires so they don't become accidentally energized during the replacement process.
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Keep all circuit wiring intact for reuse with the new panel. Replace deteriorated wiring as needed.
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Dispose of the old panel properly since it contains hazardous materials like mercury and lead. Recycling centers accept old electrical panels.
Install the New Replacement Panel
With the old panel out of the way, the new one can be neatly installed:
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Position the panel properly and attach securely to the wall or other sturdy mounting surface.
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Cut new wall openings if adding a recessed panel. Install appropriate framing and fireproofing.
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Make sure the new panel board fits flat against the wall with no gaps behind it.
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Anchor the panel using manufacturer's specified hardware. This usually involves secure bolting.
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Re-establish the copper grounding connection. A ground wire or conduit ground must be properly reattached.
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Feed interior cables back into the new panel's wiring channels and cavities. Keep wires neatly organized.
Make All Electrical Connections
The existing circuit wiring can now be terminated at the replacement panel:
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Connect the supply feeder wires from the utility or electrical source back into the main lugs or top breaker.
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Properly land each branch circuit wire on its corresponding new circuit breaker or fuse. Reference labels or the old panel wiring diagram.
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Follow manufacturer torque specs when tightening lug connections on the bus bars and breakers. Under-tightening leads to dangerous overheating.
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Double-check that all wiring is neatly routed, secured, and connected to the appropriately rated overcurrent device for that circuit.
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Make sure no bare wire or conductors are dangerously exposed.
Energize and Test the New Panel
With all wiring carefully completed, the new panel can be powered up and tested:
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Remove lockout/tagout devices from the main disconnect switch or breaker.
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Close the main disconnect or switch on the main breaker to energize the new panel.
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At the panel, switch each circuit breaker on one at a time while checking for proper operation of connected electrical loads.
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Use a multimeter to verify correct voltage at each panel bus bar and coming from each circuit breaker.
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Address any tripped breakers or malfunctions. Examine affected wiring for faults.
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Discuss any panel or wiring issues with the licensed electrician overseeing the work.
Have a Licensed Electrician Inspect and Approve
As a final best practice, the completed panel replacement should be inspected by a licensed electrician prior to returning the system to normal use. They will check for:
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Proper grounding and bonding to panel enclosure
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Secure, adequate conductor terminations
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Any exposed or damaged wiring
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Correct breaker and fuse sizing for connected loads
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Verification of stable voltage and loads on each circuit
Only after the electrician has certified the new panel and system as code-compliant and safe to energize can normal building electrical service be fully restored.
Replacing a commercial electrical panel is a complex project with serious hazards if mistakes are made. Hiring a professional electrician is highly recommended. While this overview covers the major steps involved, there are important additional safety protocols and electrical codes that must be strictly followed to ensure a successful outcome. Proper planning, preparations, and attention to detail are imperative when undertaking this type of major electrical system upgrade.