Power Quality & Equipment Protection

Our most important job is to deliver safe, reliable electricity to your home. Due to a number of factors inside and outside your home, the voltage of your electric service can vary slightly. Most of the time you won't even notice these voltage variations, but modern sophisticated electronic equipment can be very sensitive to even small, split-second electricity fluctuations.

Common power quality symptoms and causes

The table below describes the most common electrical disturbances.

What is it?
Why is it a problem?
Typical product protection solution
Sag A short-term decrease in voltage levels A sag can cause damage to your electronic equipment. Your computer system is especially sensitive to this problem.

Uninterruptible power supply (UPS)

Voltage regulator

Surge A sudden dramatic increase in voltage Some transients can cause major damage to electronic equipment or computer data and can also interfere with radio/TV/communications equipment.

Surge protector

UPS with built-in surge suppression

Swell A short-term increase in voltage A swell can lead to stressed or damaged electronic components, which cause premature equipment failure. UPS


Additional signals riding on the power line that can interfere with the operation of equipment On your computer, electrical noise can introduce glitches and errors into programs and data files or cause printer errors. Power line filter
Power outage A total loss of power, which can last anywhere from fractions of a second to hours If you are using your computer when an interruption happens, you'll lose all data stored in your computer's short-term memory (RAM). UPS

A good first step toward correcting power quality problems in your home is to look for the source of the disturbance. Many times power quality problems occur as a result of inadequate or poor home wiring.

1. Check wiring and grounding

Proper wiring and grounding are essential for the smooth operation of sensitive electronic equipment.

  • Check your appliances for loose or damaged plugs and connections and repair or replace them.
  • If a piece of equipment has operating problems, first check to see if it is plugged into a grounded outlet. A simple hand-held device available at most hardware stores can help you determine whether your outlets are properly grounded.
  • A ground is often needed to meet safety standards because some appliances could otherwise be shock hazards. If your outlet does not have a ground, a licensed electrician should upgrade it.

2. Move your equipment to a dedicated circuit

Avoid putting sensitive devices (computers, DVD players and stereo equipment) on the same circuit as furnaces, air conditioners and kitchen appliances.

3. Keep a power quality log

If disturbances happen, write down the date, time, duration and a description of what occurred. This will help you – and us – track down the cause.

4. Use surge protectors

Using a surge protector is one inexpensive way to protect equipment from power fluctuations. It protects equipment by rerouting excess energy from temporary over-voltages. However, this device will not eliminate power fluctuations.

What to look for:

  • UL TVSS 1449 rating – a certification label from an independent test lab such as UL (Underwriters Laboratories) or ETL (Electrical Testing Laboratories) on the package.
  • ANSI/IEEE C62.41, Category A (for higher exposure environments, use Category B) – The maximum amount of voltage that will reach your equipment as a result of having it connected to a surge protector.
  • UL 330 voltage rating – This performance standard ensures that power disturbances are recognized and routed away from your equipment instantaneously, providing effective protection and keeping your equipment safe from damage.
  • Catastrophic event protection for safety – a fast-acting fuse that reacts quickly and shuts down your system in the event of a dangerous wiring problem.
  • Site-wiring fault indicator – indicates there may be a problem with the wiring of the outlet.
  • Protection working indicator – lets you know that the surge protector is working as intended.
  • Connection lines for phone lines, television cables and other data communication lines. 
  • Line-noise filters – otherwise this noise could disrupt your equipment's performance.
  • A lifetime product warranty and insurance coverage on connected equipment.

5. Consider main circuit panel protection

A surge protector installed at the main circuit panel safeguards your appliances from power fluctuations that originate outside your home. This type of surge protector requires installation by a professional electrician.

6. Add an uninterruptible power supply (UPS)

A battery back-up system, also known as an uninterruptible power supply (UPS), is designed to immediately switch your computer to emergency back-up power to allow you to work through brief power outages without losing data or experiencing downtime. A UPS also provides protection from voltage sags. Sags are short-term decreases in the voltage level. 

What to look for:

  • A UL 1778 rating
  • The number and type of outlets you need
  • Run-time – the bigger the VA (volt amps), the longer the run-time
  • Length of battery life, battery replacement cost and availability
  • Site-wiring fault indicator – indicates there may be a problem with the wiring of the outlet
  • Connection lines for phone lines, television cables and other data communication lines – be aware that damaging power disturbances can also reach your equipment through cable and telephone lines
  • A lifetime product warranty and insurance coverage on connected equipment