Re: 120 khz X-10 / INSTEON 'filters' ; was Re: X10 Interference from the Cellet Cellphone Charger

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Tue, 02 Oct 2007 17:40:58 GMT, "Jeff Volp" <JeffVolp@xxxxxxx> wrote in
message  <KovMi.165523$ax1.132501@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>:

>That air-gap is an Interesting idea on isolating your system.  We have a
>Leviton surge protector at our main panel, but I haven't found any "earth"
>ground for the house.  Our water main is plastic due to the alkalinity of
>the soil.  All utilities come in underground, and the ground reference
>must be out at the underground utility bunker, if there is one at all.

For a residential ground, steel rebars encased in concrete would serve well
in alkaline soils that would otherwise corrode scratched, copper-plated
steel ground rods placed directly in the soil. Solid copper rods would work
too but are too soft to install in hard or rocky soils. Google: Ufer ground
The air-gap isolation is used in combination with other isolation
techniques. My HA PC and Web Server, for example, are in a surplus
equipment rack that is on rubber wheels. Ethernet to the outside world from
the rack is over fiber. Serial RS-232 and RS-485 comms are via ethernet-->
RS-xxx hubs on the other (grounded) side so they too are isolated from the
rack. And audio to the AV rack is also fiber. Most of this is done with
high-quality surplus gear that is a generation or two out of favor. EBay
reigns in equipment recycling.

I found a 24vdc-input PC ATX power supply for the HA PC. (It isn't big
enough for the latest power-hog CPUs and so it has placed a welcome,
arbitrary cap on power consumption. Sometimes restraint is imposed on us by
externalities and we are wise to acquiesce ;-)  It is powered by a pair of
transformer-based 12vdc chargers that are also connected to a pair
automotive-sized, deep-cycle batteries. So the power supply is galvanically
isolated even if the air gap relay and SSR aren't opened.

What's still missing is a lightning detector to isolate the system
automatically -- hopefully even intelligently and not doing the right thing
at the wrong time ;-)

... Marc
Marc_F_Hult
www.ECOntrol.org