Shielded Cat 5, 6

Three employers back where we were doing a bunch of automation in a coatings plant, all our comms (whether Ethernet, Modbus, Blue-hose, or whatever) was done inside EMT, so shielding wasn't really a consideration. Had we been hanging in free air, we probably would have used it simply as a matter of "At least that's one failure mode we can rule out without thinking too hard."
 
It depends on the high voltage situation. I wired a BMS into a battery plant with mostly 480vac service to lots of equipment. The runs of CAT6 were so isolated from the power service wires that shielded was not necessary.

However in a home where 240vac can be inches from CAT6 it might be necessary wiring into the walls. Shielding is to protect communications protocols from RF and noise from high voltage.

Rules: never wire communication wires (modbus, tcp/ip/Ethernet) in parallel with anything over 50v ac or dc. Don’t “pull them together” in a run.

If you have an intersection of high voltage wires, be perpendicular to the wires. All drains (grounding) of shielding should be connected in the middle of said run. Ground a 200’ run in the middle of possible, or on one end only. Do not drain on both ends.

www.advancedrooftopcontrols.com
 
FWIW, tech support from AD insisted that the cable from CLICK to a GS20 VFD must be shielded to prevent errors in communication. Maybe so for industrial but this is in my home and it had been error free for years. Nothing close to the Cat 6.

Hint. Do not upgrade the CLICK firmware to 3.70. Went back to 3.6 and all is fine again.

A real PIA when my first thought is usually operator error.
 
Good question. I always work in the industrial setting where most Ethernet is shielded and for some ready is always using grounding the shield on both ends.

Which makes no sense to me. We all know to only ground analog (4-20ma) at one end. Should be same concept for comms right?
 
Dsg319 said:
Which makes no sense to me. We all know to only ground analog (4-20ma) at one end. Should be same concept for comms right?
Click to expand...
Yup. Ground loops and AM radios are sooooo much fun (snicker). Though I seriously question just how much of a problem it really is, considering that our power strips are grounded, our server racks are grounded, and maybe one of every twenty or so customers even goes so far as to ground their IT gear to the rack. With so many grounds and possible loop/sink pathways, a modern data center probably resembles a plate of tossed spaghetti more than it does a well thought-out system. Yet it all somehow works...
 
ptonsparky said:
FWIW, tech support from AD insisted that the cable from CLICK to a GS20 VFD must be shielded to prevent errors in communication. Maybe so for industrial but this is in my home and it had been error free for years. Nothing close to the Cat 6.

Hint. Do not upgrade the CLICK firmware to 3.70. Went back to 3.6 and all is fine again.

A real PIA when my first thought is usually operator error.
Click to expand...
120vac to 24dc transformer on the table could be enough to make it noisy. I agree on shielding that cable.
 
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