Grounded RJ-45 connections 2

[johningram]

Where can i get the rj-45 plugs (the male piece) that have the ground connection for a good price. Im looking at only buying a few like 10 or less. Although for a good price i would buy more.

Also i have read on the net it may be better to only ground one side of the wire and not to both switches. Only one switch. Is this true and why? I would think most people would have just grounded both sides.

 

[robertjo24]

Try

http://www.digikey.com

(800-344-4539)

 

[Sphoneman]

For shielded station cabling- only 1 end is grounded. Usually in the closets, so that all equipment is bonded together- with no voltage potential.

For shielded distribution cabling- both ends are grounded & if between buildings, lightning protection installed.

Steve
tele-dataservices.com

 

[Servamatic]

For screened and shielded BOTH ends are to be bonded.
At the workstation it is accomplished with a screened equipment cord plugged into the NIC on a computer which is bolted to the chassis and grounded via electrical.

Whenever you install screened (ScTP) or STP cable you should be checking for voltage between the equipment cord and the NIC BEFORE you plug it in. If you have more than a 1 volt reading you need to find the difference in potential before you make the connection to a computer.

Richard S. Anderson, RCDD

http://www.servamatic.net

 

[johningram]

Im not so sure were talking about the same thing.
We have a gigabit switch in one part of our office and another gigabit switch in another side of the office. We are connecting them with 1 Cat-5e shielded cable. It has a small metal wire going through it and there is aluminum foil shielding wrapping the 4 pairs of cables.

Now on the switches there is metal connections on the outer part so that this shielded wire can connect to the switch or nic right where it plugs in. The end rj-45 plugs are special in that they are made of metal so that they will ground the wire to the switch or nic.

So do i connect it at both of my switches or at just one side or the other.

 

[Servamatic]

ANY time you run a Screened TP connect the drain wire and foil at BOTH ends. The cable you described is called Screened not shielded Twisted Pair. ScTP

Richard S. Anderson, RCDD

http://www.servamatic.net

 

[daronwilson]

I believe it might be more correct to say that anytime you use ScTP for ethernet, the shield/drain should be grounded at both ends.

There are a few other applications where we use shielded/screened twisted pair wire that require only one end to be grounded (mainly instrumentation).

Good Luck!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[Servamatic]

I spent 3 months doing Instrumentation at the Shell Oil Refinery. Since they wanted to control what happened to any stray voltage, if it had a drain wire it was bonded at both ends, period. All shields were bonded at both ends as well.

So I am not sure what Instrumentation you are referring too, but since the original question was regarding Ethernet I didn't feel it necessary to specify.


Richard S. Anderson, RCDD

http://www.servamatic.net

 

[daronwilson]

Our instrument engineers (the guys with EE or PE after their names) routinely design and install control systems for Georgia Pacific in their paper mill and process controls. Additionally, we have about 45 water treatment plants under our belts with a UL listed panel shop manufacturing control panels. I'm referring to instrument wiring, 4-20ma loop current, almost always grounded at the panel and floating at the instrument.

While the original question did refer to connection two switches, your response that I took issue with was:

ANY time you run a Screened TP connect the drain wire and foil at BOTH ends

While that may be applicable to ethernet, it is not blindly appicable to all wiring using screened or shielded twisted pair.



It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[Sphoneman]

Maybe I wasn't understanding correctly, or the specs have changed (I haven't used STP for over 5 years)

I thought by grounding STP on both ends it would create a ground loop.

I was trying to verify my thoughts previously after checking your posts. I found this info:

http://www.imcnetworks.com/faq/FAQ-ENET.asp

Steve
tele-dataservices.com

 

[daronwilson]

Grounding both ends certainly can produce ground loops. Years ago when I was doing broadcast audio, it was an absolute nitemare to have a radio studio with literally hundreds of shielded twisted pair wires and have a problem with a ground loop. Obviously we want things at the same ground potential, how we get there sometimes is a bit tricky.

Good Luck

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[johningram]

So bottom line......

Should i ground my ETHERNET Cat 5e cables to one switch or both switches?

Remember.... This is a connection between a switch and another switch. Both are gigabit switches.

 

[daronwilson]

Is the rest of your cabling ScTP? Why are you using that for this link?

I would build it bonding the shield at each end and check for any difference in ground potential if it were me. Just be aware that now you have two ground paths between the devices, one on the screen/shield of the data cable, and one via the chassis and the power ground. Sometimes, this loop can be an issue.

Good Luck

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[Servamatic]

If everything is bonded as per the standard and you check for a difference of potential between the cable and chassis' you won't have a ground loop issue.

A ground loop in the power or video signal occurs when some components in the same system are receiving its power from a different ground than other components, or the ground potential between two pieces of equipment is not identical.

This is why we bond everything to equalize the ground potential.


Richard S. Anderson, RCDD

http://www.servamatic.net

 

[johningram]

Im not positve what the term Sctp means. Im guessing its the type of wire im using?

I have a gigabit switch in one part of our office. Another gigabit switch in another part of the office far far away. 200ft. The wire connecting the two together is a grounded/shielded cat-5e wire. WE MUST have full gigabit speeds between these 2 switches because we have 23 users using that single line to reach anywhere else on the network. They each have 10/100 and some even have gigabit nics. That means that if there all demanding full bandwidth (assuming there all 100m/bit connections) at the same time there will be a 2300 m/bit possible load. That is more than twice the gigabit speed and 23 times the 100 m/bit speed. Of course not everyone will be using it at the same exact time. But it would be pretty darn slow if it was only a single 10/100 line connecting our two switches together. We have a lot of graphic intense stuff and the files are large and stored on the servers. Some graphic files (pictures) are hundreds of megabytes in size.

I dont know what you mean by ground differences. How do i check for them and why doesnt the documentation on the switches speak of doing it?

Bottom line...
Connect ground to both sides or one side??????????????

 

[Sphoneman]

If you have knowledge of utilizing a multimeter. The safest way is at each end(forget about connectors & pairs for now).

First use your meter & verify your ground of your electrical outlet to your rack/cabinet/chasis in both equipment areas. Optimumly you should have no AC or DC voltage. If you do verify where your rack is grounded to building ground vs. the electrical ground.

Strip off your jacket at one end meter the shield & drain to your chasis.Optimumly you should have no AC or DC voltage. If that is the case, then attach to a screw down or bond.

Now follow the same procedure for the other end.

If that side is the same- then you should be okay to proceed with making your real connections.

Steve
tele-dataservices.com

 

[josepablomir]

1) Ground only ONE side, at the Switch in the wiring closet.

2) Grounding two sides will NOT be necessary from a communications point of view, and WILL create ground loops (temporary and/or permanents).

Regards,

Jose.-


_________________
Pablo Mir

http://www.pablomir.com

pm@pablomir.com
NJ, USA

 

[johningram]

Whats the benefit to grounding both sides? Can i just ground one side and be done with it? Or is that way inferior? I dont want to go as far as multi meter testing.

 

[Jtodd]

John,

ScTP is Screened Twisted Pair, as apposed to Shielded, or Unshilded (UTP).

Justin T. Clausen
Physical Layer Implementation
California State University, Monterey Bay

 

[Servamatic]

Lets put it this way....
If you are not going to bond BOTH ends, don't bother bonding either end.
Why even install something if you don't plan on following the manufacturers specs? The manufacturer most likely will not guarantee the installation either if you don't adhere to all specs for the product.
If you don't want to test for ground faults with a multi-meter you shouldn't be running shielded or screened cable.

As to Pablo comment that:
"2) Grounding two sides will NOT be necessary from a communications point of view, and WILL create ground loops (temporary and/or permanents)."

That is simply wrong.
#1 It may be necessary in certain environments.
#2 Manufacturers spend a large amount of time making sure there products will function properly and write the specs for them accordingly. I don't know of a single manufacturer that will agree with Pablo's blanket statement.
If you don't take the time to test for difference of potential on that drain wire or shield at both ends, then you are not installing properly and then YES you would be more likely to have problems.
It takes all of about 5 seconds at each end to test with a multi-meter.


Richard S. Anderson, RCDD

http://www.servamatic.net