How To Ground Shielded Ethernet Cable

How To Fix a Ground Loop

Written by Don Schultz, trueCABLE Technical Sales Representative & Fluke Networks Certified Technician

Quite often I go questions about how to prevent a ground loop, or how to perform a ground loop prepare when using Ethernet cablevision. Information technology is great that people are reading Shielded vs Unshielded Cable. That is the starting point. Knowing yous could run into this issue is half the battle. Fixing or avoiding it is the other half.

What I did not item in that blog, even so, was to evidence how to avert a basis loop birthday. I promised I would do so, and here it is.

What exactly is a ground loop?

Footing loops may occur when you lot are running shielded Ethernet cable in the following scenarios:

● The shielded run is between two buildings that are on their own AC mains (meters), or have 2 or more different subpanels that are separately world grounded.
● The shielded run is inside the same building that has multiple Air-conditioning subpanels (a great example is a factory), and these subpanels are using dissimilar grounds.
● The shielded run goes to a WiFi AP or camera exterior, and there is a lightning protector involved that uses its own ground point. Then that same run is grounded nonetheless again to the Ac ground inside your house/building.

The abode installer is likely to run into the third scenario. Professional person installers are probable to encounter all three.

Practice you run into the overriding pattern? There are multiple points of grounding that occur in each installation. This has the potential (pun not intended) to create a state of affairs that has the following outcomes:

● Unexplained bit/transmission errors in your network. Worse even so, these errors are typically intermittent.
● Equipment damage (far less likely, but possible)
● Personal injury (extremely unlikely, but a remote possibility in extreme scenarios where very high Ac or DC voltages are involved). Fortunately, the conductors inside Ethernet cable are quite thin in comparison to electrical wire. The conductors will likely turn cherry red and melt before you become a charcoal briquette. Though, you might get a nasty fire or jolt.

How and why does this happen?

Electricity is your friend, but it can also harm yous. For reasons that only an electrical engineer can explain fully, having multiple points of footing tin crusade ground potential differences in your cable system. Those ground potential differences are then literally looped dorsum as common manner voltage, and go injected across your Ethernet cablevision. It'southward not voltage yous want--nosotros are non talking about PoE in this example.

What is the solution?

Never run shielded cable? No. That is not the solution. In my blog linked higher up, there are scenarios when you must use shielded cable. The main i, and one that I consider inviolate, is when y'all are running Ethernet cable outside in open up air scenarios. Air move causes electrostatic discharge (ESD) build-up on your cable, especially in the dry seasons. This ESD needs a way to drain off, and this would be via the cable shield/drain wire and your ground. I learned the hard fashion on this one. The toll? A dead $200 Ubiquiti outdoor Wi-Fi AP.

You can get away with unshielded CMX outdoor cable in directly burying scenarios, bold the cable is cached and making contact with dirt, and that cable is not in proximity to an underground Air conditioning line.

The solution is to exist aware this situation tin occur and mitigate information technology before yous have problem. Here are ii infographics showing common scenarios and how to wire stuff up:

Scenario #i. You are running shielded Ethernet cable between two buildings with multiple subpanels or AC mains involved.

Take notation in the to a higher place scenario, Building A. The patch panel should be a shielded patch console if ane is used. If the shielded patch panel has an auxiliary ground wire attachment (most practise) so either do NOT hook it up or hook information technology upward to your edifice's Air-conditioning basis wire. Practice not separately ground that auxiliary wire to another basis (like a ground rod). You will merely create another ground loop.

Scenario #ii. Y'all are running shielded Ethernet cable to a PoE device outside, like a Wi-Fi Access Betoken (AP). The AP is protected by a lightning/surge protector mounted exterior and is grounded directly to globe.

In the above scenario, absolutely none of the outdoor shielded Ethernet cable is grounded inside your construction. It is isolated to the exterior ground provided by your lightning/surge protector. This volition isolate your within network equipment. No, it will not protect you from a direct lightning strike, but some protection is better than zip.

So, there you have it. This is how to avert ground loops in two common scenarios. Of course there are more than scenarios than the two I described in a higher place. When planning your network, judicious use of shielded Ethernet cablevision volition serve you well. Be sure to utilise shielded where needed, and unshielded where needed. Both types of Ethernet cable have their identify. Happy Networking!

 trueCABLE presents the information on our website, including the "Cable University" web log and live chat support, as a service to our customers and other visitors to our website subject to our website terms and weather. While the information on this website is about data networking and electrical bug, information technology is not professional person advice and any reliance on such material is at your own risk.

Source: https://www.truecable.com/blogs/cable-academy/how-to-fix-a-ground-loop

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