ifi LAN iSilencer

Hi again, @davetheoilguy - My recommendations for LAN isolation instead of surge protection is from this article.

As I understand it, the author argues that LAN surge protectors encourage surge voltages to find a path to ground through them, which of course causes large and damaging upstream currents as well. By isolating the equipment instead, a lightning voltage must find a local pathway instead, which while still damaging, now localizes the problem instead of letting it spread downstream.

Let me use my own situation as an example. I have about 50’ between my router and home entertainment system.

I use a LAN isolators for the Ethernet cable that feeds that system at the stereo end. This increases the breakthrough voltage from the normal Ethernet (1.5kV per side) from 3kV to ~ 7.5kV.

However, if I put in a LAN surge protector at my living room, I am reducing the breakthrough voltage to ~1.5kV because it’s now just 1 Ethernet jacks isolation and the surge "protector" which is under 100V. That’s what causes the damaging current flow. I potentially now have melted Ethernet in my walls.

With an isolator anything less than a 7.5 kV surge has to find a path in my data closet, probably through the router power supply, or the incoming coax, a much safer and much more localized event than spreading that current through my home.

Of course, I’m not actually a surge scientist, I’m just sharing how I understand the article to read and why I avoid LAN surge protection inside the home. OTOH, if I had say, outdoor fiber which converted to Ethernet through my exterior wall I’d definitely want to consider a LAN surge protector outside. Also, I do use a coaxial gas discharge tube for the cable modem outside, and air-gap the cable modem from the rest of my system via fiber. I’m the paranoid kind. :)

Hi @davetheoilguy

I wonder if we are talking about two different things? There’s a surge protector on the equipment that goes through the power cord, which I have no issue with, and there are LAN surge protectors (which I think are iffy) and LAN isolators which I recommend.

Here is an example of what I’m talking about, the Tripp Lite which meets IEC 60601-1 for use in patient care vicinity, which have no ground but does add 4kV of isolation. Also, while the components inside are very cheap, I don’t know of any isolators that cheap. Usually cheap is around $70 here.

Ethernet LAN surge protectors, ironically, are much cheaper.

So far, I haven’t seen any hospital grade LAN isolators which also include some sort of surge protection. If you find one online let me know, I’d love to learn about it.

Let me know what you find!

I would avoid any Ethernet device with a ground wire. Based on an article I read a year or two ago, Ethernet surge protectors encourage high currents through the Ethernet cables. The better strategy indoors is to use Ethernet isolators which typically offer around 4kV of isolation between one side and another. This will force a surge current to take another path besides through the wires.

About the only place I might consider one is at the entrance to a home.  Personally I use an external gas discharge to protect the cable company's coaxial and internally use an Ethernet to fiber converter to create an air gap between their modem and my router.