AC Power filter and phone line filter (homemade circuit breaker)

Do you think that tiny circuit will stop what three miles of sky could not?

Where does that surge energy go? Does this circuit stop or absorb that energy?

Notice the ground wire simply carries the surge completely around the circuit. And other components divert that surge energy into the ground wire where it connects directly to the appliance on right side connector.

Most of what would work in this circuit is already inside every appliance. Internal appliance protection assumes that surge energy gets earthed before entering the buillding. Again, where does that massive energy get dissiipated? In this circuit? In the appliance? Of course not.

Destructive surges seek earth ground. Once permitted inside a building, destructive paths to earth may be everywhere. Protection means the surge is given earth BEFORE entering a building.

Protection means massive surge energy gets absorbed and dissipated harmlessly in earth. IOW any wire that would carry a surge into the house must first be earthed where it enters the building.

Did you know all telco lines already have a 'whole house' protector installed for free? What actually provides protection? Not that protector. Telco 'installed for free' protector is so effective when connecting each wire in that cable to earth ground - ie 'less than 10 feet' to earth. Where is surge energy harmlessly dissipated? In earth and before that surge can enter a building.

Whereas cable and telephone have protection installed for free, AC electric does not. So that protection already inside all appliances is not overwhelmed, install (and properly earth) one 'whole house' protector. See GE, Siemens, Square D, Kieson, Cutler-Hammer, Intermatic, Levition, et al for effective solutions. No such solutions are sold by APC, Belkin, Tripplite, Monster Cable, etc. Some sources:

See that wire that is not drawn as a wire? It connects a surge on any incoming wire to directly to the 'protected' appliance. Just one reason why such circuits can sometimes provide surges with even more destructive paths around protection inside the appliance. Instead earth the surge before it even enters a building.

The electric mains most certainly do in the US and Canada.

. It is not like a circuit breaker. It is a surge suppressor.

You have not described your interest - what you want to protect.

If MOVs on power circuits are hit repetitively hit with large surges they will deteriorate and eventually can fail. The failure can lead to a fire. Commercial surge suppressors in the US are covered by UL standards. Part of the UL standard is that overheating MOVs be removed from the circuit. The device shown does not have that protection. Years ago I had a homemade surge suppressor which I stopped using because it lacked that protection. I assume standards in other countries require equivalent protection.

I would strongly advise against any device like this that is not UL listed (or the equivalent for other countries). The UL standard includes a lot more than just disconnecting MOVs.

Excellent information on surges and surge protection is in an IEEE guide at:

And one from the US-NIST at:

The IEEE guide is aimed at people with some technical background. The NIST guide is aimed at the unwashed masses. .

. Poor w_ can't figure out how plug-in suppressors work. It is explained in the IEEE guide - they work by CLAMPING (limiting) the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing). The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40).

Note that all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. These multiport suppressors are described in both guides. .

. w_ has a religious belief (immune from challenge) that surge protection must use earthing. Thus in his view plug-in suppressors (which are not well earthed) can not possibly work. w_'s religious blinders do not allow him to read the explanation in the IEEE guide. .

. Service panel suppressors are a good idea. What does the NIST guide say? "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless." Service panel suppressors do not limit the voltage between power and phone/cable wires. The major cause of damage to equipment is probably high voltage between power and signal wires (see the example in the IEEE guide starting pdf page 40).

All w_=92s manufacturers except SquareD make plug-in suppressors.

For it=92s =93best=94 service panel suppressor SquareD says "electronic equipment may need additional protection by installing plug-in [surge suppressor] devices at the point of use."

For real science read the IEEE and NIST guides. Both say plug-in suppressors are effective.

-- bud--