On Tuesday, October 27, 2015 at 11:02:04 AM UTC-4, westom wrote:
On Monday, October 26, 2015 at 7:04:19 PM UTC-4, Muggles wrote:
I do understand what you've been saying about earthing. The current has
to have an entry and exit point as it's searching for it's target.

Surges that do damage are hunting for earth ground. A lightning strike is a direct connection from cloud to earthborne charges maybe 5 miles distant. A shortest electrical connection may be three miles down to earth and four miles through earth to those charges. If appliances get in that path, then damage occurs.


Three miles down to earth is reasonable. Another 4 miles through earth is not.
The vast majority of the lightning strike energy will be dissipated close
to where it strkes earth. It's also obviously not about the "shortest"
path, or lightning bolts would just come straight down and there would be
no surge damage anywhere. It's about multiple paths, of varying resistance..



A direct strike to AC wires far down the street is incoming to every household appliance. Now that current must hunt for an outgoing path to earth via some appliances (and to charges maybe four miles away). If that current is connected to earth BEFORE entering a structure, then no destructive hunt exists inside the house.


Sure, if it was theoretically possible in a perfect world to intercept
100% of the surge, then that would be true. But in the real world, it's
not possible. Which is why the IEEE, NIST recommend a tiered strategy
which includes multi-port plug-in surge protectors for PCs, TV, etc.



Best protection for TV cable is a hardwire from cable to single point earth ground. Then a surge need not enter on TV cable.


IEEE says otherwise.


AC electric and phone cannot connect directly to earth. So a 'whole house' protector does what that hardwire does better - connect a surge to earth..

If every wire inside every incoming cable makes a low impedance (ie less than 10 foot) connection to earth, then an incoming and outgoing path (the hunt) need not exist via appliances.


IEEE and NIST say otherwise. Read the guides.



A protector is only a connecting device to what does protection. Protection is a connection to and quality of earthing electrodes at the service entrance.

The questions asked many times, but never answered. A Boeing 777 has
no direct connection to ground, yet it's protected from surges, how is
that possible? If protection is impossible without a direct earth
connection, how can the surge protection which WTom admits is built into
every appliance, work? How can that minimal protection inside an
appliance be effective, yet the plug-in not only can't work, but it causes
damage? BOTH are operating under the same limitation, ie no direct,
short connection to earth.




Every effort to improve earthing and lower impedance (ie shorten that hardwire) increases appliance protection. Then a surge is less likely to blow through protection inside appliances. A surge is less likely to find earth destructive via appliances.


Wooohh Pilgrim. The story is changing. You've said 100 times that
with a surge protector at the panel, it was impossible for a surge
to ever reach an appliance. Now apparently it is possible.


Earthing is how protection was done over 100 years ago. And how it is done in every facility that cannot have damage. Protectors are only connecting devices to what really does protection - single point earth ground.

Earthing is part of a protection strategy, but it's not the whole strategy.
Read the IEEE and NIST guides.