Let's separate the issues shall we. The National Electric Code allows you to replace an ungrounded two slot receptacle which is NEMA 1-15R type, with a NEMA 5-15R type three wire receptacle if that receptacle is protected by a Ground Fault Circuit Interrupter (GFCI). So for any given circuit there needs to be one GFCI which protects all the outlets which you are going to change to the 3 wire NEMA 5-15R type. That GFCI can be a combination GFCI Circuit Breaker, A stand alone GFCI that is mounted in it's own gang of an electrical device box, or a combination GFCI and NEMA 5-15R Receptacle that is placed between the receptacles to be replaced and the source of supply. All of the receptacles which are converted with a GFCI in place of an Effective Fault Current Path back to the source of supply must be Labeled "No Equipment Ground". This will provide a reasonable setting against electric shock if a portable appliance, such as a vacuum cleaner, develops a fault that energizes it's exterior conductive surfaces. As soon as the current begins to escape the circuit and flow through the human who is holding the vacuum cleaner the GFCI will open the circuit and shut off the flow of current in milliseconds. With the exception of Babies and those who already have an irregular heart rhythm this will prevent any injury but the shock will still hurt. The startle effect of the shock can cause you to fall because when you get shocked all of your muscles contract but the stronger ones win the internal tug-of-war. That is especially dangerous if you are on a ladder or right next to or on a stairway.
Electrical surges are an entirely different matter. A surge is a destructive current flow caused by a sudden change in the supply voltage to the building. These voltage spikes are caused by a lot of different things which happen either inside or outside the building. A GFCI will not respond to a surge because the current flowing in the two wires is still the same. What is more likely to happen with a GFCI is that the surge will destroy it's sensing mechanism and it will fail safe with the circuit de-energized. A single surge can destroy a lot of electronic devices and a lot of appliance solid state controls. To protect your home and it's electrical appliances and devices from a surge you will have to install a whole house Surge Protector. A surge protector contains components which are connected between the separate wires of the circuit which will conduct if the voltage rises too high or too quickly. This equalizes the voltage between the wires of the circuit so that, even though the voltage may rise to several thousand volts for a few nano-seconds, no destructive current will flow because there is no substantial difference in voltage between the parts of the circuit. To actually protect all of your electronics you must protect all of the pathways which bring electrical current into your home. That includes coaxial cable and telephone wires. Since fiber optic cables do not carry electrical current you need not be concerned about them. This means that your whole house surge protector must include protection for all of the conductive pathways into your home.
Still on surge protection you may want to add individual protectors to particularly expensive electronics such as televisions and computers. Once again the protector selected must include protection for all of the conductive pathways which connect to the device you are trying to protect. It is not uncommon for a television to have a coaxial cable, power cord, Ethernet cable, and even a phone cable. The protector chosen to protect it would have to include protection ports for all of these which are connected.
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Tom
