Originally Posted by Neurorad
Are you trying to say that there is no benefit to using a SPD, at the service entrance, if there is already a direct connection to the ground, at the service entrance?
AC electric may be three wires. Which wires do not connect to earth? All but one has no earth ground. A homeowner is expected to know what is meant by earthing.
Most AC wires carry energy destructively inside a building. Once that energy is inside, nothing can stop a destructive hunt for earth.
AC service is earthed to meet code. Does that mean every single wire in every cable connects to earth? Obviously not. Therefore surge protection does not exist. Perspective. Earthing for human safety says only one wire is earthed. Earthing for transistor safety says all wires must be earthed.
If this is new, then you will not understand any of it until you reread multiple times. For me, nothing new and technical makes sense without at least three rereads. Apparently you have not yet reread them enough. Rereading is required for anything that is new and technical.
As said repeatedly, every incoming wire must connect to earth. Directly earth all three AC electric wires to have surge protection. Then AC electricity is not provided. So connect the other two wires to earth via a switch - as Dr Kenneth Schneider said:
> Once a threatening surge is detected, a lightning protection device grounds the incoming
> signal ... Thus, redirecting the threatening surge on a path-of-least resistance
> (impedance) to ground where it is absorbed.
Or Sun Microsystems for each and every wire:
> These should divert the power of the surge by providing a path to ground
Or the military's Grounding, Bonding, and Shielding for Electronic Equipments and Facilities:
> Transient suppression design. To provide effective protection, equal suppression
> must be installed line-to-ground on each service conductor input and the neutral input.
In a 1997 discussion among Ham operators entitled "Lightning and ground systems":
> The basic scenario is to install a Single Point Ground System that is installed
> at the building entry. It shunts everything to ground before it goes in the building.
> If you can keep it outside, then you don't really have to do much inside. IMO
> disconnecting the cables is more psychological than preventive.
Again, protection is always about where energy dissipates.
Were they discussing earthing for human protection? Or earthing for transistor protection? Again earthing must meet and exceed
post 1990 code requirements.
If you do not earth every wire, then surge energy may be inside the building. Every thought and question must reference or ask, "Where does energy on each wire dissipate?" Southwest Bell was blunt about this in "How can I protect my DSL/dialup equipment from surges?"
> By far, the whole house hardwired surge protectors provide the best protection. When a whole
> house primary surge protector is installed at the service entrance, it will provide a
> line of defense against surges which enter from the power company's service entrance feed.
> These types of protectors can absorb/pass considerably more energy than any other type of
> protector, and if one does catastrophically fail, it will not typically be in a living
> space. ...
> Plug in strip protectors are, at best, a compromise. At worst, they may cause more damage
> than they prevent. While they may do an acceptable job of handling hot to neutral surges,
> they do a poor job of handling any surge that must be passed to ground. ...
> Then, to add insult to injury, some strip protectors add Telco and/or LAN surge protection
> within the same device, trying to be an all-in-one sale. Remember bonding? When Telco
> or LAN protection is added to a strip protector, if the premise ground, which is not designed
> to handle surges, cannot handle all of the energy, guess where that excess energy seeks
> out the additional grounds? You got it! The Telco and LAN connections now becomes the
> path, with disastrous results to those devices. ...
Most AC wires enter without earthing. Connect a wire short (ie 'less than 10 foot') to single point ground via a 'whole house' protector. If any surge on any wire is not earthed (directly or via a protector), then an entire surge protection system is compromised - no matter how expensive the protector. Surge hunts for earth destructively via appliances. Protection is a discussion about where energy dissipates. Every wire - not just one - must connect to earth.