Signs Your Commercial Building Needs an Electrical Panel Upgrade
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An electrical panel that was perfectly adequate for your building ten years ago may be quietly struggling to keep up with today's electrical demands. Commercial buildings accumulate load over time — more equipment, more workstations, more HVAC capacity, more technology infrastructure — and the panel that powered the original build isn't always sized for what the building has become.
The problem is that electrical panels don't fail dramatically. They degrade gradually, and the warning signs are easy to rationalize away as minor inconveniences rather than read as what they often are — indicators that the panel is operating at or beyond its limits. Knowing what to look for is the first step toward addressing it before it becomes an outage, a failed inspection, or a safety event.
This guide covers the most common warning signs, explains what causes them, and outlines what a panel upgrade actually involves for a commercial building in Wisconsin. If you're already seeing several of these signs, our commercial electrical service and maintenance team can assess your panel and give you an honest read on where things stand.
Before getting into the warning signs, it helps to understand what the panel is doing and why it matters.
Your commercial electrical panel — also called a main distribution board, switchboard, or panelboard depending on its size and configuration — is the central hub of your building's electrical system. It receives power from the utility, distributes it to branch circuits throughout the building, and houses the circuit breakers that protect those circuits from overloads and faults.
When the panel is properly sized and in good condition, all of this happens invisibly. When it's undersized, aging, or failing, it shows up in the symptoms described below.
The occasional tripped breaker isn't unusual — that's the protection system doing its job. But breakers that trip repeatedly on the same circuits, breakers that trip under normal operating conditions, or breakers that require multiple resets before they hold are telling you something important: that circuit is regularly exceeding the breaker's rated capacity.
In a commercial building, this usually means one of three things. Either the circuit is genuinely overloaded and needs to be relieved, the breaker itself is worn and failing, or the panel doesn't have adequate capacity to support the building's current load distribution. Any of those three diagnoses leads to the same place — the panel needs attention from a qualified commercial electrical contractor.
Lights that flicker or dim when other equipment starts up — HVAC systems, elevators, compressors, or large motors — are indicating a voltage sag. Voltage sags happen when a large load draws more current than the panel and its feeder conductors can cleanly supply, causing a momentary drop in voltage across the building.
Occasional, very brief dimming when a large motor starts is not necessarily alarming. Persistent flickering, noticeable dimming that lasts more than a fraction of a second, or flickering that happens under routine load conditions points to a panel or service capacity issue that warrants professional evaluation.
An electrical panel should be at or slightly above ambient temperature. If the panel cabinet, the breakers inside it, or the area around it is noticeably warm or hot, that heat is coming from somewhere — and in an electrical panel, heat means resistance losses, which means something is wrong.
Common causes include loose or corroded connections, overloaded conductors, failing breakers drawing excess current, or breakers that are so fully loaded that they're generating heat under normal operation. This is a situation that requires immediate professional attention — thermal issues in electrical panels are a leading cause of commercial electrical fires. Our team can perform thermal imaging as part of a commercial electrical maintenance visit to identify exactly where the heat is coming from.
Electrical panels are sized for a specific load at the time of installation. When that load increases substantially — a new HVAC system, additional manufacturing equipment, a new tenant buildout, EV charging infrastructure, a server room expansion — the panel that served the original configuration may no longer be adequate for the new one.
This is one of the most common scenarios we see in commercial buildings that haven't had a formal electrical assessment in several years. The building has evolved, the electrical demand has grown, but the panel hasn't changed. A load calculation will tell you whether your current panel still has adequate capacity or whether it's being pushed beyond its design limits. This is something we assess as part of any new construction or commercial remodel project, but it can also be done as a standalone evaluation.
Commercial electrical panels have a functional lifespan, and most manufacturers and electrical engineers consider 25 to 40 years a reasonable range for a well-maintained commercial panel — with significant variability based on the quality of original installation, maintenance history, and load conditions.
Beyond the age of the panel itself, older panels may use breaker technology that is no longer manufactured, making replacement of individual failed breakers difficult or impossible. Some panel brands from certain eras have documented reliability issues. And older panels were simply not designed for the electrical loads that modern commercial buildings carry. If your panel is 25 years old or older and has never been evaluated by a licensed commercial electrician, that evaluation is overdue.
Many Wisconsin municipalities require an electrical inspection when a building permit is pulled for renovation or addition work. If that inspection reveals a panel that doesn't meet current code — whether for capacity, breaker type, grounding, or labeling — you'll be required to bring it up to standard before the permit closes.
Discovering this mid-renovation is disruptive and expensive. If you're planning any permitted work on your building, having the panel evaluated before you apply is worth doing. Our design-build electrical team includes panel assessment as a standard part of pre-construction planning on any project.
This one is not a warning sign — it's an emergency. A burning smell near the electrical panel, visible scorch marks on breakers or the panel interior, or discoloration around any electrical connection point means there has been an arc or a sustained overload that generated enough heat to char something. This requires immediate attention.
If you're experiencing this, stop using the affected circuits, contact a licensed commercial electrician immediately, and notify your building's occupants if there is any risk of fire spread. Do not wait. Our team can be reached at kohlelectric.com/contact.
Understanding the causes helps you anticipate problems before the symptoms appear. The most common causes of commercial panel issues fall into a few categories:
Gradual load growth is the most common cause of panel inadequacy. Buildings that have added tenants, equipment, or systems over the years without a corresponding electrical infrastructure review are often running panels that were never designed for their current load.
Deferred maintenance allows small issues — loose connections, early-stage corrosion, failing breakers — to become larger ones. Annual electrical maintenance that includes panel inspection and torque checks on connections catches these issues before they become failures.
Original undersizing occurs when a panel was specified to meet minimum code requirements at the time of installation rather than being sized for growth. A panel installed with 90% of its capacity already spoken for leaves no room for the building to evolve.
Age-related degradation affects breaker mechanisms, insulation, and connections over time regardless of load conditions. Breakers that are 30 or 40 years old may not respond reliably to overload conditions — the mechanism that's supposed to trip the breaker under fault conditions may not perform correctly when it's needed.
A commercial panel upgrade is more involved than a residential panel replacement, but it follows a predictable process for a qualified contractor. Here's what to expect:
Load analysis — Before any equipment is specified, we calculate your building's current electrical load and project future requirements based on planned additions or changes. This determines what size replacement panel or additional distribution equipment is needed.
Equipment specification and procurement — Commercial switchgear and panelboards are specified, procured, and scheduled for delivery. Our electrical gear and equipment team has supplier relationships that give us access to equipment and lead times that most contractors can't match.
Permitting — A commercial panel upgrade requires an electrical permit in Wisconsin. We handle the permit application and all required documentation.
Planned outage coordination — Replacing a main panel requires a planned outage, typically coordinated with the utility for the service disconnection. We work with building management to schedule this during the lowest-impact window — nights, weekends, or a planned shutdown period.
Installation — The new panel is set, all existing circuits are transferred, connections are torqued to spec, and the system is tested thoroughly before power is restored.
Inspection and closeout — The installation is inspected by the local authority having jurisdiction and a final inspection report is provided for your building records.
Even if you're not seeing active warning signs, proactive inspection is the best way to catch developing issues before they become failures. As a general guideline:
Our commercial electrical service and maintenance program includes all of the above and provides written documentation of findings so your building's electrical health is tracked over time.
These are two different problems that sometimes overlap. A panel can be old but still adequately sized for your current load, or it can be relatively new but undersized because your electrical demand has grown substantially. The way to tell is a load calculation — a licensed electrician measures or calculates your building's actual electrical demand and compares it to your panel's rated capacity. If demand is consistently above 80% of rated capacity, the panel is functionally undersized regardless of its age.
Sometimes, yes. If your main panel has adequate service capacity but is simply out of physical space for additional breakers, adding a sub-panel fed from the main can solve the problem without a full main panel replacement. However, if the main panel itself is at or near its amperage capacity, a sub-panel doesn't solve the underlying problem — it just moves it. A proper load analysis will tell you which approach is appropriate for your situation.
Most commercial panel upgrades are completed in one to two days of electrical work, plus the time required for the planned utility outage — which is typically a matter of hours. The longer timeline items are usually permitting and equipment procurement, both of which we manage as part of the project. Total project timeline from decision to energized new panel is typically two to four weeks depending on equipment lead times and permit processing in your municipality.
It requires a planned power outage for the duration of the panel swap — typically four to eight hours for a standard commercial panel replacement. We work with building management to schedule this during the lowest-impact period. For facilities where any downtime is unacceptable, a temporary power solution can sometimes be arranged for critical circuits during the outage window.
Panel upgrades are generally not covered by standard property insurance unless the need for replacement was caused by a covered event — a surge, a fire, or similar. In Wisconsin, Focus on Energy rebates are primarily targeted at efficiency improvements rather than infrastructure replacements, so panel upgrades on their own typically don't qualify. However, if the panel upgrade is part of a broader project that includes qualifying efficiency improvements — like a lighting retrofit — those efficiency measures may still qualify for rebates independent of the panel work.
An electrical panel that's struggling doesn't announce itself clearly. It shows up as nuisances — breakers that need resetting, lights that flicker, a panel that runs a little warm. The temptation is to address each symptom individually and move on. The smarter move is to recognize the pattern and have the panel professionally assessed before the accumulated stress results in an outage or a safety event.
If your commercial building is showing any of the signs described in this guide, the right next step is a professional electrical assessment. Our team serves commercial facilities across Milwaukee, Waukesha, Brookfield, Wauwatosa, Menomonee Falls, Racine, Kenosha, Madison, and throughout southeastern Wisconsin. View our full range of commercial electrical services or contact us to schedule an assessment — we respond within one business day.
Kohl Electrical Services provides commercial electrical service, panel assessments, and panel upgrades for facilities across southeastern Wisconsin. Request a quote or explore our commercial electrical services.
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