Re: is x10.com dead?

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Wed, 01 Mar 2006 16:43:27 GMT, "Jeff Volp" <JeffVolp@xxxxxxx> wrote in
message  <PakNf.482883$qk4.116787@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>:

>
>We live up on a ridge where lightning is a significant danger.  We had a
>close lightning strike at our last house, and part of the alarm system
>was taken out.  Since the Ocelot is the core of our HA system, I didn't
>want a direct electrical path from it to the valves outside (RS485 link
>& switched 24VAC).  With X10, we have the house wiring and whole house
>surge protector to provide some measure of isolation.  But, anything can
>be fried if we get a direct hit.

How on earth (pun intended) does being coupled to power lines that stretch
from your house to the power plant afford you with "some measure of
protection" ?

It is precisely because RS-485 is readily isolated using optical couplers
that RS-485 is an excellent and common choice for what you want to do.

You do need to have a DC source on each side of the opto-couplers but it
can help you avoid the electrical path through the power line and X-10.

We've had several episodes of lightning-induced damage through the power
lines taking out GFI's, security system, phones, ethernet/computers, etc
despite whole-house "surge" protection at the meter installed by the
electrical utility. (FWIW, we live in the city near a river.)

I've opted for fiber optic ethernet connections and improved earth
grounding rods among other things.

... Marc
Marc_F_Hult
www.ECOntrol.org