Residential | FPL | Voltage Variances

Voltage Variances

Equipment damaged by spikes | Types of voltage variances | More power related information

Electronic equipment is easily damaged or destroyed by

  • low voltage and
  • short bursts of high voltage known as spikes, including
    • lightning spikes and
    • switching spikes.

Equipment damaged by spikes

High voltage spikes can cause damage to

  • VCRs
  • computers
  • televisions
  • microwaves
  • stereos
  • sump pumps
  • well pumps and
  • air conditioner compressors.

Types of voltage variances

The table below describes the cause and potential risks of different types of voltage variances.

Variance Type




High Voltage Spikes


In Florida, residents experience thunder and lighting nearly 1/3 of the year. Studies show that for every thunderstorm day, there are approximately two lightning strikes per square mile. Strikes can carry

  • voltage in excess of 1,000,000 volts, and
  • thousands of amps of current.

If lightning strikes an unprotected home, the risks include

  • fire and
  • damaged electrical equipment

Switching Spikes

Appliances such as

  • refrigerators
  • furnaces
  • vacuum cleaners
  • washing machines and
  • electric hand tools.

These spikes are significantly smaller than lighting strikes, but occur more frequently.

Over a period of time the small but continuously occurring spikes will slowly wear out electronic equipment.

Low Voltage

Typically caused by fault conditions in motors.

Signs of low voltage damage include the smell of

  • burnt insulation and
  • wiring.

Low voltage can cause an electrical motor to slowly burn up.

More power-related information

The following topics provide more information on electric power in the home.