Electric Surges

What happens if lightning strikes?

Surges from electric hookups?

What Are Power Surges?

A power surge is one form of electrical power disturbance. There are four main types of power disturbances:

  • Voltage dips (also called "sags" or "brownouts")
  • Electromagnetic interference
  • Radio frequency interference
  • Power surges (also referred to as "voltage surges" or "transient voltages")

    Power surges are generally considered to be the most destructive of the four types of electrical power disturbances. Power surges are spikes in voltage.

    They are very brief, usually lasting millionths of a second. Power surges can vary in duration and magnitude, varying from a few hundred volts to several thousand volts.

    No matter where you live, your home experiences power surges. How Does a Power Surge Cause Damage?

    In the United States, most homes use electrical power in the form of 120-volt, 60 Hz, single phase, alternating current. However, the voltage is not delivered at a constant 120-volts. With alternating current the voltage rises and falls in a predetermined rhythm. The voltage oscillates from 0 to a peak voltage of 169 volts. Most appliances and electrical devices in your home used in the United States are designed to be powered by this form of generated electricity. During a power surge, the voltage exceeds the peak voltage of 169 volts.

    A spike in voltage can be harmful to appliances and electrical devices in your home. An increase in voltage above an appliance's normal operating voltage can cause an arc of electrical current within the appliance. The heat generated in the arc causes damage to the electronic circuit boards and other electrical components.

    Smaller, repeated power surges may slowly damage your electronic equipment. Your computer or stereo may continue to function after small surges occur until the integrity of the electronic components finally erode and your satellite system, cordless phone, or answering machine mysteriously stops working. Repeated, small power surges shorten the life of appliances and electronics.

    Where Do Power Surges Come From?

    There are several sources of power surges.

  • Electric utility company during power grid switching.
  • Lightning, the most powerful form of power surge.
  • Large appliances; air conditioners and refrigerator motors turning on and off.

    Power surges can enter a home through several paths. Lightning can take the path of the cable TV, satellite dish cable, incoming telephone lines, or through the incoming electrical service line.

    Protecting Your Home or RV From Power Surges:

    Multiple point surge protection plan.

  • Protection of the incoming electrical service
  • Protection of phone lines and cable TV lines
  • Point-of-use surge protectors for sensitive and expensive appliances

  • When deciding on what type of and how much surge protection is needed, each house or RV and its contents should be assessed individually. An electrician knowledgeable about power surge protection systems and the history of problems in your area is a valuable resource.


    Similar to the high voltage surge, caused by:

  • Tearing power connections apart with a vehicle or tripping over them.
  • Running a generator that isn't properly isolated from the commercial power system.
  • Running a faulty appliance in your RV that melts down.
  • Plugging in faulty power adapters.

    Caution for RV owners:

  • Do NOT ever run a generator without first disconnecting from commercial power.
  • Do NOT trust an automatic transfer switch to protect your RV.
  • Do NOT start your generator, while any electrical equipment is running.
  • Do NOT stop your generator, while any electrical equipment is running.

  • Artificial surges are the most common cause of electrical damage!