Westbrook Panel Problems - 1/2 Power & 170 volts - Lights Blowing Up

Introduction - "Only 1/2 the power is working at my house"

When a homeowner in Westbrook called us with a scary problem—half their unit losing power while the remaining working circuits started blowing light bulbs—we knew this wasn't a standard tripped breaker.

Voltage problems like this are extremely dangerous and can fry every appliance in the home.

What followed was a precise, methodical diagnosis that ruled out common issues at the meter and panel, and led us to a hidden danger: a critical failure in the main service wiring itself. Read on to see the diagnostic process, the surprising culprit, and the crucial warning every homeowner needs to know.

Panel showing voltage spike

The Initial Hypothesis vs. The Reality - "Why are my lights blowing up"

Our initial assessment was that the customer might be dealing with two separate issues: one possibility was a faulty main breaker or corrosion on the panel's bus bar, and the other was a loose connection in the lighting circuits.

To begin the diagnostic process, we started by testing the voltage at the meter. Using a multimeter, we measured both legs and found each reading a solid 120 volts, which is normal for residential service. We then moved to the electrical panel’s main breaker and repeated the voltage test, finding the same readings there. This suggested the incoming supply from the utility was intact, and the main breaker was not the source of the problem.

The Breakthrough: Dangerous Voltage Swings

The real breakthrough came when we turned the branch circuit breakers back on. Immediately, one leg of the power plummeted to just 60 volts while the other surged to 170 volts—dangerously high and well above the normal operating range.

This dramatic voltage imbalance is a classic sign of a bad neutral connection somewhere in the system. We knew that if the neutral wire failed, the return path for electricity would be compromised, causing unpredictable voltage swings throughout the home. This condition could easily damage appliances or create hazardous conditions.

The Diagnosis: Confirming the Neutral Failure & Explaining 170 volts

To further narrow down the cause, we considered whether the issue could be originating from the utility side, but that seemed unlikely since the first floor was being fed from the same meter enclosure and was not experiencing any problems.

We proceeded to tighten all neutral and ground connections at both the meter and the electrical panel, ensuring that every screw and terminal was secure. Additionally, we conducted a thorough visual inspection of the service entrance cable running between the meter and the panel, looking for physical damage, signs of arcing, or corrosion. Despite these efforts, the issue persisted, which was both puzzling and concerning.

The Roadblock and Temporary Verification

At this point, with a neutral issue remaining as the only logical explanation, we found ourselves at a crossroads. The challenge was determining how to further diagnose and resolve the issue without incurring substantial costs if we overlooked something critical.

To verify our suspicions and avoid unnecessary expense, we devised a temporary workaround. We ran a piece of 10/2 Romex cable out the second-floor window, disconnected the original service entrance cable, and temporarily energized the panel using the Romex. This allowed us to isolate the panel from the suspected faulty cable.

During this process, we discovered a crucial clue: the copper wire running to the ground rods terminated at a lug, but extended two inches beyond it, entering another lug that was used to connect the service entrance ground wire to the neutral bar of the meter.

The Root Cause: Galvanic Corrosion in the Service Wire

Upon closer examination, it appeared that the aluminum wire from the service entrance cable had been tightened down directly onto the copper ground wire.

This improper connection can cause a chemical reaction known as galvanic corrosion, which degrades the aluminum wire over time. In this case, the corrosion had progressed to the point where the aluminum wire could only deliver correct voltage when no load was present. As soon as any electrical load was applied, the compromised wire could no longer carry the current, resulting in the hazardous voltage fluctuations we observed.

After reconnecting the service entrance cable, the issue remained unresolved. However, when we temporarily energized the panel with the Romex, the electrical system functioned perfectly, confirming that the original cable was indeed the culprit. With this definitive diagnosis, we opted to replace the service entrance cable from the meter to the panel.

This permanent solution fully restored safe, reliable power to the home and eliminated the dangerous condition for good. The experience underscored the importance of proper wiring techniques and regular inspections, especially in homes with aluminum service conductors.

Conclusion & Emergency Safety Takeaway

The degraded aluminum connection caused by galvanic corrosion was a time bomb waiting to fail, resulting in chaotic voltage swings between 60 volts and 170 volts. This wasn't just an inconvenience; it was an emergency that could have led to a house fire or total appliance loss.

EMERGENCY WARNING: Never ignore blowing bulbs or extreme power fluctuations (dim/bright).

When you see half your unit lose power, coupled with voltage surges, it's a critical sign of a failed neutral connection. This requires immediate action—turn off your main breaker immediately to protect your electronics and prevent an electrical fire, then call Greater Portland Electric right away. We use meticulous diagnostics to find and permanently fix these complex, dangerous issues.