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#160097 05/20/05 11:50 AM
Joined: Dec 2003
Posts: 886
H
Member
I just looked at the installation instructions for the Siemens screened patch panel, I've never used one so I'm not familiar with them. If you can deal with the cost it should be fine although the shielded jacks won't be needed. I also don't see a provision for connecting the ground bus to an external ground- maybe I missed it.

Oops, there it is, right in front of me!

Two ground lugs are provided (one on each side of panel) for attaching 4.115mm (6 AWG) ground wire to ground...

-Hal

[This message has been edited by hbiss (edited 05-20-2005).]

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#160098 05/20/05 01:15 PM
Joined: Jan 2005
Posts: 135
M
Member
I agree that it is definitely more pricey to use the shielded panel oppesed to the non-shielded one, but this customer spec'd shielded cable where there is no visible need for it. Why not use the right product to terminate it at the centralized point??
If you need to save the cost ok, but if the customer is paying for it, why not use the right panel and make the install look professional, I don't want to offend you Hal but wirenutting all the drains is a sloppy installation to these eyes.

P.S. It is Siemon not Siemens. [Linked Image]

#160099 05/20/05 05:51 PM
Joined: Dec 2003
Posts: 886
H
Member
don't want to offend you Hal but wirenutting all the drains is a sloppy installation to these eyes

Come on, I know you could do it so it looks professional I know I could. There are lots of shielded cables and just as many times where they must be used (not necessarily like this particular situation). You learn to terminate the drains or shields in a "neat and workman-like manner" without help from factory assemblies because the don't usually exist.

-Hal

-Hal

#160100 05/22/05 12:59 PM
Joined: Jul 2004
Posts: 625
S
Member
As some have said, the correct answer is to terminate them to shielded RJ-45 plugs. Such plugs exist, and are what you use with shielded Cat 5. Don't take the shields to ground, because that in combination with that grounding connection in the equipment will create ground loops, which can create worse problems than the problems the shielding is intended to guard against.

#160101 05/22/05 01:32 PM
Joined: Jan 2005
Posts: 135
M
Member
I know I could make it look good by wirenutting the drains to a ground wire, but the problem I have with it is that as soon as something changes and things are moved around the clean job usually disappears, if it were all done on a patch panel the integrity of the "neat and workmanlike" installation remains after any changes were made.

#160102 05/22/05 03:02 PM
Joined: Dec 2003
Posts: 886
H
Member
As some have said, the correct answer is to terminate them to shielded RJ-45 plugs.

I only said that because the equipment that they plug into has regular unshielded RJ-45 jacks and I'm not sure if shielded plugs will fit into them. Also I'm not sure how unshielded plugs will fit on the end of shielded CAT5 either so you can take my advice as needing some validation.

I think this all illustrates the problems created when you try to second guess the manufacturer and do something they didn't think was necessary. If everything had shielded jacks you would simply use screened CAT5 and shielded plugs. Obviously this equipment was intended to be used with regular CAT5 and plugs so that is what you should be using. The manufacturer knows what the environment will be like where the equipment will be used and if screened CAT5 was needed they would have made provisions for it and included instructions on how to terminate the grounds.

Sometimes a little knowledge is dangerous.

-Hal

#160103 05/22/05 03:48 PM
Joined: Jul 2004
Posts: 145
C
Member
I would go with what gfretwell said as the first response. The 'neat and workmanlike' part could be achieved by stripping off ~12 inches of the sheathing, terminate into the plug at one end with the ground doubled back out of the plug, and use some sleeving and a crimp lug to attach the drain to a convenient ground. I have seen this done at patchpanels here in the UK on occasion, when cat5 has been used in an 'electrically noisy' environment, didn't seem to cause any problems at 10BaseT speeds.

#160104 05/22/05 05:52 PM
Joined: May 2005
Posts: 167
B
Member
Shielded RJ45 plugs will indeed fit into unshielded RJ45 jacks without a problem.

*MOST* Ethernet equipment (hubs, switches, and network cards) made in the last 6-7 years has shielded RJ45 jacks. Prior to that they had unshielded RJ45 jacks.

However, almost nobody (in the USA) uses shielded cable with that equipment, and it works just as well with unshielded cable.

I believe that the only reason for the prevalence of shielded RJ45 jacks on newer equipment is due to EC (European) regulations requiring them. (Screened twisted pair is a lot more common in Europe than it is in the USA).

Given that Ethernet was designed to run perfectly fine over unshielded/unscreened cable (and if you go back far enough, the 10 megabit variety was designed to run over standard telephone cable--cat 3 cable did NOT exist back then), I believe that screened twisted pair cable is a solution in search of a problem.

#160105 05/22/05 07:00 PM
Joined: Jul 2004
Posts: 625
S
Member
If the equipment doesn't have shielded jacks, then the correct answer, in my mind, is to ask the engineer who specified it this way just what, exactly, he wants.

I suspect the problem with that approach, though, is that he doesn't have a clue. (Otherwise, he already would have written very careful specs for what he wants.) I'm thinking this is a case of the guy thinking, "Shielded is better than unshielded, so I'll specify shielded."

#160106 05/23/05 12:03 AM
Joined: Oct 2000
Posts: 2,722
Broom Pusher and
Member
Just thought of a few things - conserning this Shielded Cable for Operational Equipment Networks (LON Cables)!

Don't confuse "COM 3" or "COM 5" STP Cables with "CAT 3" or "CAT 5" Cables - they are two completely different Animals!

Most Building Automation Networks & LONs use "COM X" type Cable for the links between Equipment and Controllers.

On a (common/current) Siemens Control System, the Cabling between FLNs (Floor Level Network controller{s} ) and TECs (Terminal Equipment Controller{s} ), would be COM 5 STP, and connect to these devices via an RJ-11 or RJ-45 Modular Plug (some simply Terminate to Terminal Strips).

The "COM X" Cable is constructed as follows:

<OL TYPE=A>

[*] COM 3 is a single pair STP, with an overall foil shield and tinned drain cable,
which is roughly the same diameter as RG6 COAX,


[*] COM 5 is also a single pair STP, with overall foil shield and tinned drain, but is physically around ΒΌ the diameter of the COM 3 Cable.
</OL>

COM 5 Cable is used on faster LONs, and has a much higher twist ratio.

Just wanted to mention this!

Scott35

BTW:
When I saw "Siemens", the name triggered this thought!


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
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