For a better understanding, you need to know that:
20 percent of surges originate outside a house from nearby lightning strikes, which couple surges into nearby power wires
Normal utility operations can cause electrical disturbances
Perhaps the most common external surge source is when power is interrupted for any reason Ė a tree falling on wires, a car hitting a pole, wind damage, utility repairs, etc. Wires conducting electricity create a magnetic field. When power is interrupted, the magnetic field collapses, inducing large voltages in the wires. A 12-volt spark coil relies on this principle to generate many thousands of volts to fire spark plugs.
80% of surges come from within a building are generated every time equipment cycles on and off.
Internal surge levels are related to the magnitude of current being interrupted and the length of wire from the service entrance to the load.
The longer the wire and the higher the current, the bigger the surge generated when the power is interrupted.
A classic example is a coffee pot located far from the service entrance. Every time the heater kicks on and off to maintain the coffee temperature, significant surges are generated.
It should be obvious that a coffee pot cycling on and off several times an hour is a much more frequent event than a tree falling on the power wires, or a lightning storm.
What's a power surge?
The power in your home outlets is 120 volt AC power. Lightning, short-circuits and downed power lines can cause that voltage to jump by hundreds or thousands of volts. These spikes in voltage are called Ďsurgesí.
Even a surge lasting a fraction of a second can cause damage to your electronics and appliances.
What kinds of power surges are there?
Power surges can enter your home through electric power connections, telephone connections, cable connections and antennas.
What can I do to protect my electronics and appliances?
On common solution is to buy surge protectors or suppressors to help protect your home. These devices generally divert the power surge to the ground in order to keep it from affecting electronics and appliances.
What kinds of surge protectors or suppressors are there?
There are three common kinds of surge protectors or suppressors:
Plug-in surge protectors are the easiest to install. You can buy them at most electronics stores and hardware stores. They are either a box that plugs directly into a wall socket, or a strip with multiple outlets that plugs into a wall socket. You will find simple AC power plug-ins, or more complex models that offer combined protection for AC power and telephone or cable. If you have appliances hooked up to 2 potential surge sources, look for a dual protector!
Service panel surge protectors are installed at the service panel of the house (breaker box) and are designed to protect all the appliances in the house with one device. They
can be incorporated in the panel or installed outside the panel. Some of these you can install yourself, some must be installed by an electrician. Check with your local government to see if you can do it yourself.
Meter surge protectors can sometimes be installed by your local power company at the power meter on the outside of your home. There are also meter surge protectors that can be installed by licensed electrician.
Will a surge protector installed at the service panel protect the whole house?
Yes, for any appliances using the power system, but not for appliances that may also be hooked up to cable, an antenna or the phone line.
Does a plug-in surge protector protect all the sockets in the house?
In general, it only protects the socket in which itís plugged. (It does give some protection to appliances on the same branch circuit.) So, itís best to install a surge protector for each sensitive appliance in the house.