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[cswca]

Was just wondering if the CM15A has some sort of built in surge protection, sure would hate to see lightning take out both the CM15A and my computer through the usb port (live in Florida).  If not is it possible that I could plug this into a stand alone surge protector so it can still send signals through the house wiring without it affecting performance?

[Oldtimer]

Was just wondering if the CM15A has some sort of built in surge protection, sure would hate to see lightning take out both the CM15A and my computer through the usb port (live in Florida).  If not is it possible that I could plug this into a stand alone surge protector so it can still send signals through the house wiring without it affecting performance?

I had the same question when I first got my CM15A.  Here is my original question to X10 and the response I got:

As of 12/29/2004
content = What kind of isolation is there in the CM-15A between the USB bus connection and the power line interface?  Is it opto-isoloated?  I'm concerned about lightning damage from a ground loop through the CM-15A.  When a lightning storm is forecast in my area I have my computer system so set up so I can disconnect the AC, telephone, power and LAN wiring in the house from the computer. With the CM-11A I disconnected the RS-232 connection from that also.  Do I need to remove the USB connection from the CM-15A when lightning is forecast, or is it isolated so I don't have to. 


Yes, it is opto-isolated.
 
Regards,

Dave Rye
Director of Technical Services,
X10 Wireless Technology, Inc.

[Brian H]

From the FCC Database information schematic X10 filed. Could be different in later date code models. My 04 and 05 match the schematic.
The Zero Crossing signal is opto-isolated.
The powerline transmitter and receiver are transformer coupled to the powerline. There is a V130LA4 MOV across the hot to neutral power pins.
If you use a surge strip on the CM15A power input. Many have noise filters in them that can absorb X10 Powerline signals. So choosing one could be a trial and error thing.

[Oldtimer]

From the FCC Database information schematic X10 filed. Could be different in later date code models. My 04 and 05 match the schematic.

The date of my posted email from Dave Rye was 12/29/2004.  I've added it to the post. Should have included it the first time.

Between the opto-isolator and transformer detail you describe it still seems pretty ground loop free to me.  Even with the whole house surge protector that I have I still unplug other potential ground/earth loops, but not the CM15A USB connection, when a thunder storm threatens since most of the damage to small electronics that I've seen has come from multiple ground/earth points in wiring paths not the voltage surge on the power line by itself.

[Brian H]

When I worked for Motorola Communications lightning liked to spike all over the place. . I never lost one board or area; most times one or two components on many boards. Many times it was the Phone Line on remote controlled base stations.
Multiple ground point make lots of sense.

[nklght]

I have my CM15A plugged into a single device appliance surge protector.  It has not really affected the performance of the unit any.  My problem has not been the devices recieving the signal, only the Unit not recieving the remote signals.  I get the same performance with or without the surge protector installed.  All functions performed at my computer, and stored timers work without a problem.  I believe I am using a woods single appliance protector that I bought at wal-mart. 

[cswca]

Thanks everyone for the replies thus far

[nklght]

X-10,
tells you not to use surge protectors, because of possible malfunctions.  I have never had a problem with my setup not working properly because of surge protectors, the only problem I have is that the cm15a never recieves the signal.