DIY

1159 readers

3 users here now

For DIY - this is also a placeholder.

founded 2 years ago

MODERATORS

Hareuhal

Grounding an Ethernet surge protector. (lemmy.world)

submitted 3 weeks ago by Machinist to c/diy

5 comments fedilink hide all child comments

I have added a wifi repeater to the outside of my home so that my wife can watch her critter cams. It is a POE device that runs all the way back to my router.

Would like to install this surge protector but I'm getting conflicting information on grounding it. My installation is to the side of my house, not a metal pole.

Lowest effort options first, I can:

A. Place the protector inside near where the CAT5 enters the basement. Ground to a junction box that I installed that is grounded to the house panel and rod.

B. Ground internally to a water pipe or externally to the outdoor spigot.

C. Drive a ground rod where the cable exits the house and ground to it.

D. Repeat C and also bond to to the pre-existing home ground rod. (Least preferable option, rods would be on opposite corners of house.)

top 5 comments

sorted by: hot top controversial new old

[–] [email protected] 6 points 3 weeks ago* (last edited 3 weeks ago) (1 children)

Since none of the four options involve mounting this surge protector onto a metal pole, the other allowable option from the Ubiquiti quick start guide is to use a ground wire, which they call a "drain wire". Option B does not guarantee a ground connection if your home's water pipes use plastic piping for some sections, but the other three options would satisfy the Ubiquiti requirements.

However, only options A and D would satisfy the bonding requirement in the NEC -- assuming you're in the USA -- which prohibits using disparate ground rods for the same structure, ruling out option C.

So I would go with option A, as it guarantees a metallic path back to the existing grounding system at the main panel and is easy. The Ubiquiti document does not prohibit indoor mounting. And for the purpose of dissipating static charges or providing an emergency path to ground, reusing the probable 12 or 14 AWG ground wire from a junction box is perfectly acceptable.

What this Ubiquiti surge protector absolutely will not do is lightning protection, which is the one application where you would want option D (new ground rod bonded to existing system). But even then, a direct lightning strike will set any WiFi device ablaze; indirect nearby strikes though can be mitigated with surge protection, sometimes.

[–] Machinist 3 points 3 weeks ago (1 children)

Wifi repeater is one story up, and the cable runs under a metal gutter in one place. House is two stories.

Lightning protection is my concern. Direct strike, all bets are off no matter what you do, as I understand it. Given the location, figure it's unlikely to get a direct strike. However, that long cable and the gutter could easily act as an antenna and push a surge into my home network where I have NAS, server, several computers wired to the router.

Option C and mounting it to a metal pole don't seem much different to me. It does violate code. Option D is expensive and a royal pain in the ass.

You think option A is good enough for an indirect strike? Is there a better way to do this or a different device?

[–] [email protected] 3 points 3 weeks ago* (last edited 3 weeks ago) (1 children)

I would say -- in my capacity as a layperson engineer and not an electrician -- that Option A is sufficient for distant strikes, because it provides an all-copper path from this surge protector to the ground rod, assuming your home wiring is already up to code. Option B has the issue of higher resistance (for iron piping) or being non conductive (for PEX/PVC piping). Option C has the problem that while the induced current from an indirect strike is sunk into the ground, the ground differential between this separate ground rod and the ground rod serving your network equipment, might blow up your switch. These "objectionable curents" are precisely why the NEC requires all ground rods bonded.

So between Option A and D, the latter would have slightly lower ground resistance, but this probably isn't worth the substantial complexity for not much increased protection against indirect lightning strikes.

All this also applies for any sort of household device, unless you're about to install a Faraday cage, which isn't practical for a Wifi device. So I think your Option A is optimal here.

[–] Machinist 2 points 3 weeks ago

Reckon I'll go with option A, then. Appreciate the advice!

[–] Machinist 2 points 3 weeks ago

@A_Union_of_Kobolds , will you pretty please take a look at this?