Rain8Net and Thunder Storms


All my irrigation control wire terminates in an OnQ Panel mounted in a closet. I have two Rain8Net irrigation controls mounted in this panel. From there, I have ~ 30 feet of CAT5 cable that runs to a serial port on my automation PC. It seems like after every major thunder storm, the serial port that the Rain8Net is connected to will die.

This past Sat., I was getting ready to go to Tokyo again. I just spent the day setting up the Homeseer Insteon Plug-in (worked great and the lights were all setup to turn on and off while I’m away). It started to rain and some lightning hit near the house. I went to check on the PC and smelt fried electrical parts. My 40 day old Belkin UPS would not start up and the PC was dead, will not boot. I also unplugged the two Rain8Net units and tried to test them with my laptop using Rain8Master Config. I was unable to read eithe unit’s address or reprogram the units.

I bought the units last fall. I sent one unit back to WGL a few months ago for a similar problem. They were great to work with, repaired the unit and I like the product. However, I can not keep replacing serial cards and now a UPS / PC after ever thunderstorm.

What can I do to prevent this? I have it wired just like WGL shows on their web site. Do I need some sort of serial surge protector and if so, where can I get one? What can I do to minimize this from happening again?
I'd go with both. Put the optical isolator inline and put the surge suppressor on the PC serial port.
There are really two types of problems with lightning. First, there is the induced voltage from a nearby strike. Things that other people have discussed like surge suppressors and opto-isolators will help. You could add surge suppressors on the AC lines running out to the irrigation valves. Even better would be to use the Rain8 to drive opto-isolated relays to actually control the valves. Opto-isolator relays are cheap in the surplus market, and can be considered expendable.

The other problem with lightning is a direct strike. If it gets directly onto a conductor, all bets are off. Nothing can really protect against the amount of energy in a direct strike. Opto-isolation means nothing. Hopefully, most of that energy will find a direct route to ground. But it can leave behind a path of destruction in its wake.

I do have some experience with both types of strikes.

As someone who just got forced to replace all HA equipment because of a direct hit (plenty of surge protectors and industrial UPS units inplace), I can attest that you can't stop the 2nd type Jeff mentioned. I guess that's why you have home owners insurance, just make sure that if you run a business from home , or work from home, that you talk to your insurance agent,or they might not cover your installion at all.

I did invest in a few more specialized surge protectors, but that's only to handle the nearby hits. Oh yea, as for lightning never striking the same location twice, it does :)