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ethernet cable shielding?


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Many network knowledgeable folks gather around here, so hoping you can point me in the right direction.

 

I'm setting up a home gigabit network using UTP cat 6 cable. The cat 6 run from router to switch is 17 meters long and 12 of those meters run along and 10cm away from either flourescent tubes or LED strips. The runs from switch to clients are shorter and away from tubes/LEDs so these are of no concern (I think). Unfortunately, around here I'm not finding STP or FTP cat 6 unless I buy 1000 feet, which I'm not going to do. So I'm wondering if I should add any shielding to those 12 meters? I could wrap the cat 6 in aluminum duct tape, or slide the cat 6 inside copper tubing, or do nothing and live happily ever after.

 

What do you think I should do?

 

Thank you!

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Ethernet cables are balanced common mode noise rejection. Any noise is going to couple across the pairs that are 180 degree out of phase and thus they will cancel out.

 

Siemons published a paper called the antenna myth and they do a good job explaining how noise immune balanced cabling that is Ethernet is.

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+1 re Plissken's advice.

 

Also, a shield defeats the benefit of ethernet's ground isolation between components.

 

What AnotherSpin refers to is that a tell-tale sign of shielded ethernet cables is that the RJ-45 connector is metal coated, at least on its left and right sides.

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3 hours ago, Bob Stern said:

+1 re Plissken's advice.

 

Also, a shield defeats the benefit of ethernet's ground isolation between components.

 

What AnotherSpin refers to is that a tell-tale sign of shielded ethernet cables is that the RJ-45 connector is metal coated, at least on its left and right sides.

 

Yes, I guess metal coated RJ-45 connectors go together with with shielded cables always. I experimented once with a Supra Cat8 cables which were used to connect server to NAA endpoint - removed metal covers from RJ-45 connectors, it was easy to do. There was change in SQ, imo, and I like it. 

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Thanks guys. Some peculiarities of what I'm asking: I'm not using shielded connectors nor cable. Just plain plastic RJ45 and UTP CAT6 cable. The question is if I should build a shield around the cable for the 40 feet that run along the fluorescent tubes and LED strips (and 4" apart). What do you think?

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12 hours ago, plissken said:

Ethernet cables are balanced common mode noise rejection. Any noise is going to couple across the pairs that are 180 degree out of phase and thus they will cancel out.

 

Siemons published a paper called the antenna myth and they do a good job explaining how noise immune balanced cabling that is Ethernet is.

 

So UTP ethernet cables don't radiate any RF/EMI?

 

Also asking @Miska

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46 minutes ago, asdf1000 said:

 

So UTP ethernet cables don't radiate any RF/EMI?

 

Also asking @Miska

 

That's not what you were asking in your original post. If you are worried then just get CAT7 that will have foil around twisted pairs and overall shield. I don't recommend that however and others have already mentioned this.

 

BlueJeans will do CAT6 F (Belden stock) and leave the foil disconnected at each end.

 

The cabling standard at the health care provider I work is CAT6A U/UTP. The next campus we are doing will have 12,000 runs.

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2 minutes ago, plissken said:

That's not what you were asking in your original post.

 

Original post is not mine... 

 

I was asking a general technical query, perhaps not related to the discussion above.

 

But still - so UTP cables do radiate RF/EMI ? Or don't ?

 

 

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8 minutes ago, asdf1000 said:

 

Original post is not mine... 

 

I was asking a general technical query, perhaps not related to the discussion above.

 

But still - so UTP cables do radiate RF/EMI ? Or don't ?

 

 

 

Any thing that transmits will radiate something.

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5 minutes ago, plissken said:

 

Any thing that transmits will radiate something.

 

For cables around (potentially) sensitive analogue audio gear, Blue Jeans Cable Cat 6A stuff (Belden) has the 'floating' shield. So you get a shield and no ground loops.

 

Might be a good option to consider?

 

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1 hour ago, asdf1000 said:

 

For cables around (potentially) sensitive analogue audio gear, Blue Jeans Cable Cat 6A stuff (Belden) has the 'floating' shield. So you get a shield and no ground loops.

 

Might be a good option to consider?

 

 

I prefer just routing cabling properly initially then go to something like BJC 6A if I can't get it optimized. It's affordable so no big deal either way. My DC-1 is fully balanced also so going balanced all the way through mitigates most of this.

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I don't seem to able to explain myself: I cannot get anything that's not UTP around here. I'm not concerned with CAT 6 emissions into analogue gear. I'm concerned with fluorescent tubes and LED strips running along the cable and close to it injecting noise into the cable or otherwise harming the signal or gigabit capability. Hence the alternatives to add external shielding to the cable such as copper tubing or aluminum foil tape wrapped around the cable. If nonsense because noise/RFI/EMI doesn't get into the CAT6 UTP, then that's ok. It's different from what I read online, but maybe I misunderstood.

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1 hour ago, LewinskiH01 said:

I don't seem to able to explain myself: I cannot get anything that's not UTP around here. I'm not concerned with CAT 6 emissions into analogue gear. I'm concerned with fluorescent tubes and LED strips running along the cable and close to it injecting noise into the cable or otherwise harming the signal or gigabit capability. Hence the alternatives to add external shielding to the cable such as copper tubing or aluminum foil tape wrapped around the cable. If nonsense because noise/RFI/EMI doesn't get into the CAT6 UTP, then that's ok. It's different from what I read online, but maybe I misunderstood.

In @plissken first response, he basically said you don't need to worry about it - UTP is fine.

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3 hours ago, LewinskiH01 said:

I don't seem to able to explain myself: I cannot get anything that's not UTP around here. I'm not concerned with CAT 6 emissions into analogue gear. I'm concerned with fluorescent tubes and LED strips running along the cable and close to it injecting noise into the cable or otherwise harming the signal or gigabit capability.

 

You don't need to worry about it with common mode noise rejection. Lookup the Siemons Antenna Myth and do some reading.

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On 5/14/2020 at 9:03 AM, LewinskiH01 said:

Thanks guys. Some peculiarities of what I'm asking: I'm not using shielded connectors nor cable. Just plain plastic RJ45 and UTP CAT6 cable. The question is if I should build a shield around the cable for the 40 feet that run along the fluorescent tubes and LED strips (and 4" apart). What do you think?


The most important thing is to use twisted pair. Belden’s “mediatwist” is bonded which means that the pairs don’t untwist at bends — that’s the single biggest way noise can get into the cable. 
 

The problem with shields is that noise from the transmitter can be projected into the receiver (and then loop back on common ground). The coupling can be capacitative.

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