Surge Protectors

westom · October 12, 2015

I would like to begin with a recommendation of a whole-house surge protector and how I might ground it to the earth properly. .

First, destructive spikes from major appliances is an urban myth. If those appliances create surges, then you are replacing clocks, TV, and all kitchen and bathroom GFCIs daily or hourly. Obvious the furnace and washing machine do not create those surges. May create noise (ie single digit volts spikes). Read a let-through voltage on any protector. 330 volts means a spike is ignored until voltage well exceeds that number.

Meanwhile, a 'whole house' protector protects from all types of surges - including any rumored appliance generated surges.

Second, protection means a electric current spike does not go hunting for earth ground destructively via household appliances. IOW that current transient connects low impedance (ie less than 3 meters) to earth BEFORE entering. A single point earth ground is THE critical component of this protection system.

Best is to have all incoming utilities entering at one service entrance. Then all make that low impedance connection to some 10 foot copper clad earth ground rod. Equipotential and conductivity are the objectives. Then voltage underneath the entire house remains constant. If the voltage on that incoming wire is same as voltage beneath a house, then no voltage difference exists inside the house - destrutively across appliances.

A utility demonstrates good, bad, and ugly (preferred, wrong, and right) solutions. Obviously a best solution exists when all incoming cables are at one service entrance. However, if cables enter at different locations, then an ugly (right) solution is implemented. Appliance protection starts with quality of and connections to this single point earth ground. Inspecting or upgrading this earthing is critical. Since this is what harmlessly absorbs hundreds of thousands of joules.

TV cable needs no protector. Best protection is a hardwire connection from cable to earth ground. A ground block (http://www.dbsinstall.com/N-images/Whatis/Driploop-1.jpg or http://files.cablewholesale.com/hires/200-278.jpg) and maybe 10 AWG (green) wire makes that connection. Now a surge need not go hunting destructively inside since a best connection to earth exists outside.

Anything that increases that earth ground also increases protection. Protection is best installed when footings are poured - Ufer ground ( http://scott-inc.com/html/ufer.htm). But you must deal with what already exists. Code says you must have at least two ground rods. For most homes, that is sufficient. However if the earth ground is expanded (using electrodes defined by the National Electrical code), then appliance protection increases.

Third, a dedicated hardwire connection low impedance (ie no sharp wire bends) to earth is protection for cable. But telephone and AC electric cannot connect directly to earth. Telco already installs a 'whole house' protector for free. Protector only does what that hardwire does better. It is only a connection to earth. Often found inside an NID box (https://en.wikipedia.org/wiki/File:Network_interface_device_ameritech.jpg). Again a ground wire must connect low impedance (ie less than 10 feet) to single point earth ground. No a surge on telephone wires need not go hunting destructive inside.

Every wire in every incoming cable must connect low impedance to earth - either by hardwire or via a 'whole house' protector. It is required by code (and other standards) on cable TV, telephone, satellite dish, and TV antenna. Unfortunately it is not required on AC electric. That protection would not exist IF a homeowner does not install it.

That summarized the most important component in every surge protection system - single point earth ground. Above describes protection that should already exist, needs inspection, or must be upgraded. Next post moves on to what is missing in most homes.

westom · October 12, 2015

Locate a bare, solid copper, quarter inch ground wire that must connect a mains breaker box to that single point earth ground. If that wire goes up over the foundation and down to earth, then ground meets code and compromises surge proetction. Wire is too long, has too many sharp bends, and is not separated from other non-grounding wires. Protecton means that wire must go through foundation and down to earth - to be many feet shorter - to have lower impedance. Inspect to confirm that wire exists, is properly installed to exceed code requirements, and actually does connect to single point ground.

A second wire will connect to cold water pipes. This bond is required for human safety. But is no longer sufficient for earth ground. That decicated earth ground (often to multiple ground rods) must exist as defined in the first post.

A 'whole house' protector must connect all incoming AC wires low impedance (hardwire not inside metallic conduit) to earth. One, rented from the AC electric company, is located behind the meter. Or can be installed in the main breaker box. Manufacturers, known for integrity, provide them including Square D, Intermatic, Polyphaser (an industry benchmark), General Electric, Ditek, ABB, Leviton, Syscom, Siemens, and Keison. A Cutler-Hammer sells in both Lowes and Home Depot. Protectors are also available in electrical supply houses (ie where circuit breakers are also sold) and on the internet. This protector is characterized by a dedicated wire for that low impedance (as short as possible) connection to earth.

One specification number is important. Lightning is typicaly 20,000 amps. No protector must be damaged by a surge. So a minimal 'whole house' protector is 50,000 amps. Simply ask or search for a 'whole house' protector. Confirm it is at least 50,000 amps (and has a UL listing). Then a sufficient 'whole house' protector has been selected.

Again, protection is always about where hundreds of thousands of joules dissipate. That (earth ground) defines 'protection' during 'each' surge. 50,000 amps defines protector 'life expectancy' over 'many' surges. Quality of earth ground, that protector's current number, and how a hardwire connects to earth are three critical concerns in a 'whole house' solution.

Protection is always about where hundreds of thousands of joules are harmlessly absorbed. A protector is only as effective as its earth ground.

Finally a last point. Each protection layer is only defined by its earth ground. Above is one protection layer - your 'secondary' protection layer. Also inspect your 'primary' protection layer. Pictures demonstrate what might be inspected to confirm a 'primary' protection layer exists:

http://www.tvtower.com/fpl.html