STP grounding help

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Lekro44

Lekro44

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Oct 28, 2015
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Hello,

I have a little problem.

I have a modem router combo with ungrounded plastic rj45 sockets. My pc has a grounded metal rj45 socket. Both the modem-router and my pc is connected to the same UPS.

I want to connect my pc to the modem-router but I only have cat5e STP cables.

Questions: I heard you only ground one end of the cable (I heard the opposite too) to avoid ground loops(even though both devices are on the same main). If I plug this cable in, would it be grounded correctly by my pc and would the shielding provide interference protection correctly?

If not, can I use this cable as a normal cable without the shielding capabilities or it is worse than a simple UTP interference-wise?

Thanks!
 
Solution
B
Your best best is to use normal unshielded cable and avoid these issues. The twists by themselves in ethernet cable provide enough protections. Interference coming into the cable is extremely rare and mostly a problem in industrial installations.

It really does not matter what kind of end the cable has. The equipment you have likely does not have the tabs internally to ground the cable. In the vast majority of the cases the grounding is done to the wall jack/ patch panels not the short patch cable between the equipment and the wall.

Ground loops are a concern but they do not occur when this is properly installed. You never connect it to the power grounds partially because you can actually get interference from other stuff...
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bill001g

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Aug 9, 2012
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Your best best is to use normal unshielded cable and avoid these issues. The twists by themselves in ethernet cable provide enough protections. Interference coming into the cable is extremely rare and mostly a problem in industrial installations.

It really does not matter what kind of end the cable has. The equipment you have likely does not have the tabs internally to ground the cable. In the vast majority of the cases the grounding is done to the wall jack/ patch panels not the short patch cable between the equipment and the wall.

Ground loops are a concern but they do not occur when this is properly installed. You never connect it to the power grounds partially because you can actually get interference from other stuff plugged into the power grounds. Also grounding in electrical is for safety because a short circuit can transfer power to it which will cause massive damage to communication equipment. You must install a totally separate grounding loop. This is fairly common in data centers where you connect every rack to this ground.

Now you really should ground both ends to avoid the shield acting as a antenna and picking up interference. You will not get grounds loops when the grounds are correctly installed even between buildings....again you are not suppose to use the power grounds.

The good news is the twists in the ethernet do such a good job of stopping interference that even if the shield acts as a antenna added interference will still cause no issues in most cases. This is why so many people brag they have STP even though they installed it incorrectly. Almost all the gains are in their head because they never had a interference problem to start with.
 
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