Electric power is rarely perfect — and when it isn’t, the impacts can range from annoying flickering lights to significant damage to sensitive equipment. Whether you’re a homeowner concerned about protecting your investment or a business owner looking to avoid costly downtime, understanding power quality conditions is essential.
At M.T. Ruhl Electrical Contracting, we work with power systems every day — from residential electrical work to Generac® generator installations and commercial electrical solutions. In this article, we break down the 9 power quality conditions most commonly seen, describe what causes them, how to recognize the symptoms, and how to protect your property effectively.
Key Takeaways
- Surges and spikes are the biggest threat — they account for roughly 80% of power quality issues.
- Voltage fluctuations – (sags, swells, undervoltage/overvoltage) are the second most common issue.
- Noise and harmonics – may not be frequent, but they cause significant operational issues.
- Generators and UPS systems – provide critical power continuity during interruptions.
- Proper grounding and layered surge protection – are foundational to a reliable electrical system.
What Is Power Quality?
“Power quality” refers to how close your electrical supply is to an ideal sine wave at your nominal voltage level. Any deviation from this ideal, even for fractions of a second, can disrupt equipment performance or cause damage over time. A power disturbance is defined as any deviation beyond acceptable thresholds from normal voltage or waveform shape.
Why Power Quality Matters?
Poor power quality can lead to:
- Flickering or dimming lights
- Premature failure of LED lighting and electronics
- Unexpected computer resets or data loss
- HVAC and motor issues
- Increased maintenance costs
- Shortened lifespan of sensitive gear
The good news? Many of these problems are predictable and preventable with proper electrical design, surge protection, and voltage regulation.
The 9 Types of Power Quality Conditions
1. Normal Voltage
This is the “perfect” electrical waveform — clean, stable, and at the correct voltage level.
- How common is it? Very rare
- Symptoms: None
- Solution: None needed — this is the ideal state
Even though this is the goal, most utility power encounters deviations before it reaches your home or business.
2. Undervoltage (Long Duration Low Voltage)
Undervoltage occurs when voltage drifts below normal levels for seconds to minutes. This is sometimes called a “brownout.” It often stems from heavy utility loading, long feeder lines, or large equipment startup loads.
- How common is it? Moderate
- Symptoms:
- Damaged LED drivers
- Audio/video equipment issues
- HVAC performance problems
- Solution:
- Professional voltage regulation systems
- Heavy-duty surge protection
Without proper correction, undervoltage can strain electrical devices and cause early failures.
3. Noise (EMI/RFI)
Noise refers to high-frequency electrical chatter riding on your normal sine wave. It’s invisible but disruptive.
- How common is it? Very common
- Symptoms:
- Flickering lights
- Electronic lockups
- Erratic network or control behavior
- Solution:
- Surge protection with EMI/RFI filtering
- Good electrical grounding and shielding
Noise is particularly problematic in environments with many electronics or motor loads.
4. Sag (Short Voltage Drop)
A sag is a sudden voltage dip for a few cycles or seconds. They are often caused by motor starts, HVAC systems, elevators, and heavy equipment.
- How common is it? Very common
- Symptoms:
- Lights flickering
- Computers rebooting
- Motors losing torque
- Solution:
- Voltage regulation systems
- Surge protection for accompanying transients
Sags may not seem severe, but even momentary drops can disrupt sensitive electronics.
5. Surge / Transient Spike
A surge or transient is a very short, high-energy spike — often caused by switching operations, motors, or lightning.
- How common is it? Most common issue — ~80% of all power complaints
- Symptoms:
- Flickering lights
- Premature LED failure
- Malfunctioning electronics
- Solution:
- Surge protective devices at key electrical points
- Whole-home or whole-building surge filtering
Surges are one of the biggest silent killers of electrical equipment. Protecting them is one of the most cost-effective strategies you can invest in.
6. Swell (Short Voltage Rise)
A swell is a brief increase in voltage above normal levels — it might last for a few cycles.
- How common is it? Moderate
- Symptoms:
- LED life reduction
- Breakdowns in sensitive devices
- Solution:
- Voltage regulation
- Surge protection for the associated spike
Short-duration voltage increases can cause stress to insulation and sensitive electronics.
7. Interruption
An interruption is a momentary loss of power.
- How common is it? Low to moderate
- Symptoms:
- System reboots
- Lost data
- Solution:
- UPS systems or battery backups for sensitive equipment
- Standby generators like Generac® systems
Even brief interruptions can lead to critical failures in computers or control systems.
8. Harmonics
Harmonics distort the pure sine wave shape and arise from non-linear loads (like VFDs, LED drivers, and switching power supplies).
- How common is it? Relatively uncommon but impactful
- Symptoms:
- Buzzing transformers or motors
- Overheating conductors
- Solution:
- Surge protection with harmonics filtering
- Specialized harmonic filters for industrial environments
Harmonics can lead to inefficiencies and overheating, especially in larger facilities.
9. Overvoltage (Long Duration High Voltage)
Overvoltage is when your system operates above normal voltage levels for an extended time.
- How common is it? Rare but destructive
- Symptoms:
- Equipment failure
- Burned LEDs
- Sensitive device lockups
- Solution:
- Voltage regulation
- Surge protection for spikes
Long-duration high voltage can destroy electronics and motors if not corrected.
How M.T. Ruhl Can Help?
At M.T. Ruhl Electrical Contracting, we offer:
🔹 Residential & commercial electrical services
🔹 Generac® generator installation, maintenance, and repairs
🔹 Surge protection solutions
🔹 Voltage regulation and power conditioning recommendations
🔹 Electrical safety and code-compliant installations
We understand both everyday electrical needs and advanced power quality issues — ensuring your home or business is safe, efficient, and resilient. If you want help protecting your electrical system from the 9 power quality problems, reach out to M.T. Ruhl — we’ll assess your needs and recommend the right solutions for your home or business.
Frequently Asked Questions (FAQ)
- What is the difference between a surge and a voltage spike?
A surge is a very fast, short-term voltage increase often caused by lightning or switching. A spike is essentially another term for the fastest and most violent surges that can damage electronics. - Can poor power quality damage my electronics?
Yes — frequent surges, sags, and harmonics can shorten the lifespan of sensitive equipment like computers, LED lights, and HVAC control systems. - Do whole-house surge protectors really work?
Yes. When installed properly at the main electrical panel and supplemented with point-of-use protectors, they significantly reduce the risk of surge-related failures. - Will a generator protect against power quality issues?
A standby generator like a Generac® protects against power interruptions, but not necessarily voltage fluctuations or surges — for that, surge protection and voltage regulators are needed. - What should I do if my lights flicker often?
Flicker is often a sign of sags, noise, or poor voltage regulation. A professional electrical evaluation can pinpoint the cause and recommend solutions.
