APC by Schneider Electric APC ProtectNet RS232 9 Pin Surge Suppressor - 200 A

I bought three of these to go between the control wires in my pentair pool control panel and the home automation interface board and outdoor controller. So far had a couple lightning strikes with no damage. However pre installation I've had many lightning strikes with no damage and the damage that I do receive is always to the low voltage pool controllers but nothing else. So my only complaint is that there is no reset switch or no way to tell if it is actually doing anything. I'm giving it 3 stars only because there is no way to confirm it is doing anything other than wishful thinking. If I find there is any way to confirm or deny it's functionality I will report back. I purchase a DB9 cable that chopped the ends off of and wired into this for a custom installation. Actually my home automation installers put the first ones and missed one line so I had to buy more parts. So I can't take credit for the idea.

These RS-232C surge protectors seem to work just like any standard surge protector, isolating each of the nine pins most likely through varistors to catch any voltage leaks that would normally cause damage. I currently have 3 of these hooked up to an industrial DE-9 multiplexer and they seem to be doing their job just fine. My only gripe is these are enormous 1-1/2 x 3 x 3/4 inches which is typical a great deal bigger than a normal DE-9 end which make them exceptionally difficult to install on a piece of lab equipment which has multiple RS-232 ports in very close proximity.