Give us some examples and URL's where people can get more info if you would please!
A TV cable (as even required by code) drops down at the service entrance. A hardwire (maybe 10 or 12 AWG) connecct from a TV coax cable to an earth ground electrode. How effective? Protection increases as impedance to earth decreases. That means every foot shorter, no sharp bends, and not inside metallic conduit. A hardwired connection to a best earthing electrode is best protection for a TV cable. Then a surge need not go hunting destrutively for earth via appliances.
Telephone wires cannot connect directly to earth. So a protector connects each telephone wire just as short to the same earth ground. In this case, a telco "installed for free" 'whole house' protector is doing what that hardwire would otherwise do better.
Codes (ie NEC, FCC) require cable, telephone, antenna, ethernet, etc to be earthed either directly or via a 'whole house' protector. That protection should already exist IF a homeowner has inspected, upgraded, or installed a single point earth ground.
Not required is same protection on the most common source of destructive surges - AC electric. Available in electrical supply houses, Amazon, eBay, and a long list of other providers both on-line and in 'brick and mortar' stores.. Siemens, Keison, ABB, General Electric, Ditek, Intermatic, Polyphaser (ProtectionGroup), Clipsal, Leviton, and Square D are some manufacturers. A Cutler-Hammer (Eaton) protector is sold in both Lowes and Home Depot. Some electric companies will rent and install one behind their electric meter.
Search for or ask for a 'whole house' protector. Which ones are best? First, as explained above, a protector must have a dedicated (green) wire for that low impedance (ie 'less than 10 foot') connection to earth. No dedicated earth ground wire means it is not a 'whole house' protector.
Second, lightning is typically 20,000 amps. So a minimal 'whole house protector for residential AC electric is 50,000 amps. That description, an earth ground wire, that specification number, and above manufacturer names make shopping easy. These are routinely sold where circuit breakers and other AC main breaker box parts are sold.
Protectors are simple science. The 'art' is a single point earth ground. Earthing (not a protector) should have most of your attention. A simplest single point ground is a ten foot long copper clad rod driven in earth as defined by the National Electrical code (NEC). Hundreds of thousands of joules harmlessly dissipate there. How to make a 'whole house' protector better? Upgrade its earth ground - what absorbs energy.. More earth ground rods. Ufer grounds (if building a new home). Encircling a building with a buried wire. Other electrodes are defined by the NEC article 250.52 or in other sources found in most libraries (such as McGraw Hill's "National Electrical Code 20xx Handbook"). A utility demonstrates good bad and ugly (preferred, wrong, and right) solutions at:
Tech Tip 08 -Duke Energy
Effective 'whole house' protectors are trivial, simple, and easily located. And defined by one spec number - at least 50,000 amps. A protector is only as effective as its earth ground. Earthing is the 'art' - where most of a homeowner's attention should focus. Every incoming cable must connect to earth via a hardwire or 'whole house' protector.
Defined are how to shop for a 'whole house' protector. And what should have most of your attention.