Grounding for modem, router and switch question.

Ocator 3 years ago updated by Heidi Hanson 3 years ago 8 1 duplicate

 Hi, can we plug this ethernet grounding adapter between modem and router? If we do have a desktop computer plugged to the router, I understand we need to use an ground loop isolator but is it okay to plug it between router and modem? If so, is this isolator plugged before or after the ethernet grounding adapter that is plugged between modem and router? I read the other questions posted here so far although I noticed you answered some but haven't answered other questions that are considered essential and similar to mine. Please answer as soon as you receive this for it is a very important question to know before considering your products. If you must know, my router has metal ports to it while my modem has no metal port.

 I have a second question if it's within your ability to answer. If the setup above is feasible, what if I decide to connect a series of switches (daisy chain) connected to a single port in my router? Does having metal ports in each and every switch connected to each other make a difference in grounding all my devices that require ethernet connection? What if one of the switches don't have metal ports? Once again, it's an important question I really need answered before considering your products. Please answer as soon as if you receive this.



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Cable modems often have groundable Ethernet ports which are (not always, but often) connected to the coaxial (round screw cable TV wire) terminal.  Therefore they are often already grounded.  My preferred way of handling this is to put an Ethernet ground-loop isolator in between the cable modem and the router (if the router has metal groundable Ethernet ports).  This takes care of any concern of creating a ground loop without the need for measuring.

Next, if you have a desktop computer, you can ground your router via the desktop computer by hooking it directly to the router with a shielded ethernet cable.  Alternatively you could ground the router with an Ethernet grounding adapter.

Our preferred way of handling things now when a groundable router with metal ports is used is like so:

1) Have the router grounded via either the cable modem (must be tested so we know that is 100% passing ground to the router) or via a desktop computer (this is a sure way) or via the Ethernet grounding adapter (also a sure way).  If NOT grounding  and testing to verify the router via the cable modem then use the isolator in between cable modem and router to be safe.

2) Use an isolator on each port of the router except for the port that is being used to intentionally ground the router

3) Ground each device (desktops are already grounded) at their location.  This would be laptops and portable devices.

4) Preferably use the Ultimate USB to ethernet grounding adapter to ground the portable laptop/other device AT the device AND ground the Ethernet cable at the device as well.  This is preferred rather than grounding it at a central location (the router or switch).

5) For adding switches to the network, I recommend using metal switches and hooking them directly to the grounded router.  Then as described above use isolators for each device.  You only want to bring "ground" to the router and in turn to all of the switches from one reliable location - never more than one location!

If you are 100% sure the ethernet port on your modem has no metal tabs or balls inside of it, then you would not need the isolator in between the modem and the router.


Hi Shaun,

 Thank you so much for your reply. If you must know, I plan to use shielded cables for all my connections. I have a few questions for the one of your preferred ways.

3) If I ground each and every device, are you saying the grounded router won't be able to pass ground to any device connected to it especially if there are switches with metal ports in between?

4) When it comes to using the Ultimate USB to ethernet grounding adapter, I was thinking of adding ground to my laptop through your USB grounding adapter instead in case I use the laptop without internet like this below,


 Would that work out or do I still need to use another grounding adapter such as the Ultimate USB to ethernet grounding adapter to plug to the laptop you mentioned?

5) I'll have you know I plan to daisy chain to 2 switches with metal ports in them. The first one will connect to a portable device. The second one will be connected to the desktop computer. The second one will also connect to a wired broadband router with plastic ports to it.

 If the desktop computer is connected to the second switch with metal ports by a shielded cable I mentioned earlier, will it still be able to pass ground to the router provided the second switch is connected to the first one by shielded cable while the latter is connected to the router by that same shielded cable?

 As for the ethernet port in my cable modem, the only metal part I see in it is just a couple of pin connectors that make contact with the connectors in any ethernet cable it gets plugged by. If you must know, the model of that modem is TC4300.E and it's a Technicolor brand.

Just to mention one other thing, this wired broadband router connected to the second switch, it will connect to a phone and a laptop. My laptop connects to the internet by a consumer USB to ethernet adapter (TL-UE300 sold by TPLink). It does not have a metal port in it. Does that make any difference in say, connecting an Ethernet grounding adapter in between this and the wired broadband router?

Please let me know what you think.

Thanks again,


In reference to point #4 above. Wouldn't grounding the laptop AND ethernet cause the laptop to complete a ground loop? Or would this only be the case if you were not using the ultimate USB to ethernet adapter? Or is it possible to have to do with the material of the laptop(mac vs pc)?

For example,  I'm curious if you can ground the laptop at the laptop and also grounded the ethernet at the mac laptop without having a ground loop. Keep in mind that the line is isolated from the switch already.


3) IF you have a router that only has plastic ports, then it is not possible to ground the router.  IF you have one of our routers, then it has metal ports and it is ground-able.  If you then ground one of our routers through any port, ALL ports will have ground.  It will therefore pass ground to all cables that you plug in.  This can be good OR bad.  We do NOT want to double-ground anything.

4) If you purchase the Ultimate adapter, you can use it without Ethernet.  You can still just plug the adapter in to the ground and use it as a grounding adapter.  Ethernet is not required.  But this is the preferred way we want to do it so that it grounds your Ethernet when you use Ethernet.  So this would be my recommendation.

5) Daisy-chaining switches is no problem, as long as you keep it I would recommend 4 devices max.  It is always better to home-run them so that they hook to the master switch/router.  I've done 3 devices such as router to switch to switch before.  It's not a problem - especially if you aren't running heavy traffic like work computers or advanced expert power users.

So what you would probably want to do here is use the Isolator in between the second switch and the desktop computer.  The second metal  switch will be getting ground from the first metal switch via the shielded Cat 7 cable.  The desktop computer is already grounded and will ground the cat7 cable you plug into it.  So therefore you need to isolate it from the switch.

That is how I would do it.

Your cable modem looks like it does not have a groundable Ethernet port.  It looks all plastic.  So the only metal you see inside are the gold plated 8 pins?  No silver-colored tabs or clips or anything?

The router has to be plugged-in directly to the modem.  You can't go through a switch or something for that.  That would not work.  So modem to router then router to switches or router to switch to switch.

Ditch the USB to Ethernet you have now.  The best way to do it is with our Ultimate adapter because we want that ethernet cord to be grounded at the same location as the computer.  This way you would also not need the Ethernet grounding adapter

Hi Shaun,

3) If I can't afford one of your routers and that I have one with metal ports, will this be able to be grounded from any grounded source whether it's by ethernet grounding adapter or a grounded desktop computer? The model of mine is an Asus RT-AC1900.

5) Even if switches have plastic ports in them, are they still useful enough for say, preventing ground from passing onto any other device to avoid ground loops unless I'm wrong?

Since you advised me to put an isolator between my desktop computer and the second switch, how is the first switch grounded? By an ethernet grounding adapter or from the grounded router?

Correct, my cable modem just has a yellow-colored plastic port with gold plated 8 pins. No metal tabs or clips.

Thanks for your answers once more.

Hi Shaun,

I am still waiting for your reply which I haven't received yet. Could you please get back to me as soon as you receive this? It has been a week.


OK so your cable modem is all plastic Ethernet port - therefore you don't have to worry about ground passing to the router.  Your router is metal and therefore ABLE to be grounded.  You could ground the router and the switches from one location using an Ethernet Grounding Adapter, and then isolate computers from this ground using the isolators.

If switches have plastic ports then yes they would be useful for isolation and isolators would not be necessary.  But I would still want to make sure each Ethernet run to such a switch would be grounded properly.

Hi Shaun,

This completely answers all my grounding questions. I appreciate all the help you've given me so far. Hopefully the products I've ordered from your website serve me well once they come at my door.

Thank you