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jwshields
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Yet Another Grounding Question! (WW Cube AC)

Sat Dec 04, 2021 5:24 am

Hi all,

I have some questions, and want to also give some background info around what I've looked at so far, no flaming out of the gate please! :)

I have a Wireless Wire Cube (60GHz & 5GHz) set that I plan on using at my home to connect the detached garage to the house, a distance of maybe 75FT (trenching is not possible)
Right now my questions are mostly focused on the house, and are phrased that way, but similar steps would be taken for the cube on the garage.
The plan is to connect the "house" cube to my RB4011iGS+5HacQ2HnD-IN
But I am getting tripped up when it comes to how to handle grounding the Cube and connecting/powering it.
I have a few different tools I can utilize here, but am totally unsure of how to proceed.
I have a good amount of shielded and unshielded ethernet at my disposal.
I also have a few GESP-POE units.

Reading the docs for the Cube, it says to use the spade plug on the cube and connect it to the antenna mast or building
Grounding: The device includes a grounding connection (marked ⏚) which you should connect to the grounding installation of the tower or building where the device will be used. This is to substantially reduce the risk of ESD and lightning damage.
Reading the Wiki page regarding grounding, the page makes a number of suggestions and assumptions..
One of them being that the metal surrounding the Ethernet port is connected with the ground plane of the devices.. This is false for the cubes. Both of my cubes do not have the spade connected electrically to the ethernet shield on the socket.
Testing the GESP-POE with my multimeter shows that both of the shells/housing for the ethernet are electrically connected to the grounding wire.
So, now, in my mind, the page on the wiki about grounding does not hold true.

Reading through ~10 different threads on the forum, I see lots of advice that conflicts with each other and the wiki/device docs.

My questions now are numerous...
1. How should I properly ground the Cube units?
2. Should I use a shielded ethernet cable from the Cube to my 4011?
3. Should I use the GESP-POE in between the two devices?
4. If 3 is yes, should I use shielded ethernet on one side, both sides, or neither? (I would think neither defeats the entire purpose of the device)
5. If I use the GESP-POE and have it on the same ground plane as what the Cube's spade is connected to (the mast of the antenna), in theory, there could be voltage fed through the GESP ground to the ground of the Cube and/or the ethernet ports on the 4011 if I'm using shielded eth. Should the GESP-POE & Cube (or GESP-POE & 4011, or all three) be on different electrical grounds if a shielded ethernet cable is used?
6. Currently my 4011 is floating and I'm not using any shielded ethernet to other devices it's connected to. Could I leave it floating with a non-shielded cable to the GESP, or use a shielded cable to the GESP to ground it? Or, use a non-shielded cable to the GESP and use the grounding screw on the 4011 itself? (This is partially tied to #5)
7. Am I overthinking this? Anything I'm thinking of seems like it'd create ground loops all around, or leave my devices at risk; both scenarios are undesirable.

In any case, thank you in advance for any guidance that can be offered
 
mducharme
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Re: Yet Another Grounding Question! (WW Cube AC)

Sat Dec 04, 2021 11:03 am

At the wireless ISP that I work for, we do not do anything special for grounding for home installs like this. We do use shielded outdoor cable for running to the radio, but do not do anything special in terms of surge protection. We only do surge protection on towers, as they are much more vulnerable to lightning strikes due to their height (and we have lost equipment due to direct lightning strikes). Pretty much all of our customers have their radios working for so many years that we have to get the customer to replace the device because it is outdated instead of an equipment failure.

You are most likely overthinking this - you don't need to do surge protection for a radio installed on your home or garage unless perhaps it is on a really tall pole, higher than surrounding trees.
 
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bpwl
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Re: Yet Another Grounding Question! (WW Cube AC)

Sat Dec 04, 2021 1:00 pm

 
Zacharias
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Re: Yet Another Grounding Question! (WW Cube AC)

Sun Dec 12, 2021 7:39 pm

Nice article...
So common ground is preferred if i understood it right ...
 
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jwshields
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Re: Yet Another Grounding Question! (WW Cube AC)

Thu Dec 30, 2021 9:18 pm

At the wireless ISP that I work for, we do not do anything special for grounding for home installs like this. We do use shielded outdoor cable for running to the radio, but do not do anything special in terms of surge protection. We only do surge protection on towers, as they are much more vulnerable to lightning strikes due to their height (and we have lost equipment due to direct lightning strikes). Pretty much all of our customers have their radios working for so many years that we have to get the customer to replace the device because it is outdated instead of an equipment failure.

You are most likely overthinking this - you don't need to do surge protection for a radio installed on your home or garage unless perhaps it is on a really tall pole, higher than surrounding trees.
I appreciate an actual answer here, thank you. In my use case, it wouldn't be any taller than surrounding trees, or heck, even the buildings they're attached to.
Based off what you said, I'm thinking I'll run shielded eth from the cube to the router, ground the cube from the spade to the pole, and ground my router to the rack/PDU, and call it a day.. As all the devices are coming from the same electrical panel.
Thank you very much for the insight though, and the reassurance that I am overthinking things!

I have read this page multiple times, even before you linked it.
While there are good tidbits of information in there, the only thing that applies to my entire post is part about shielding and the ground connections in the second scenario; as the Mikrotik docs seem to be mixed up on whether devices have their grounding terminal electrically connected to the shells of the ethernet ports. Some devices do, some don't; the 5ghz/60ghz cubes do not. I was wondering how to reconcile the fact that the docs assume the former and do not address the latter, and, because of my lack of expertise in this specific domain, I had multiple questions I posed, based off of my understanding of things.
But, thank you for the empty hand-wavey "okay kiddo move along now" post; maybe a word or two in addition to a link would make it come across differently.
Anyway, thanks for the link; my quest to find the perfect blog post about ground loops has been completed. :roll:

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