cccp sparky

When should I buy the shielded cables?

If cable hanging above lighting ballasts?

Now residential construction having the compact fluorescent ballastings. Should I be install the shielded cables?

LARMGUY

Being a low voltage guy I use it only when the device manufacturer specifies using it or when I need communication between devices and controllers such as RS485 and Manchester protocols.

__________________
There are 10 types of people.
Those who understand binary and those who don't.

sarness

Unless it is spec'd, you font need shielded cable. Try to stay a foot away from power and other such things, run at 90 degrees to those if needed.

__________________
Thread shorter.

cccp sparky

I have a shielded wirings. Does this utilizing a green ground screw, or is the screw on corner of a 4 square box okay for the bonding?

jeffmoss26

All I can say is ?????

JohnR

Are you an apprentice? Your profile says nuclear power electrician. Does that mean you get your electricity from the local Nuke plant? Where are you trying to use this shielded wiring anyway? I am really getting a feeling that you are an apprentice or a handyman trying to pass as a real electrician.
If not, sorry but that is a strange question IMO.

rnichols

Are you talking like cat5? It depends on the cable, the device.. more information would give you a better answer

mikeh32

if you dont have the right ends, shielded cable doesnt do much too

CoopElec

You should always use a green hex head 10-32 ground screw. If not use the cover screw, just make sure you put the wire through the hole behind the screw, so you dont pinch the wire when you put the cover on.

__________________
There Is No Spoon, Huh

sarness

I don't think the op has any idea as to why.

One job I went to that they had run shielded cable with a grounding type patch panel, (even had a ground wire run and wrapped around the conduit) had the cable jackets under the bonding clamps, completely defeated the purpose using shielded cable.

__________________
Thread shorter.

mikeh32

I am really wondering why you guys are using ground screws on shielded cable....

especially since this is in structured cabling.

I mean i know i am only a dumb c card, but this whole ground screw is new to me

sarness

Anything I have ever installed and needed a ground, I would run a ground back to the panel and install a ground bar to tap from.

Your mileage may vary as to what other's do.

__________________
Thread shorter.

CDN EC

Depends on what it's being used for. Some automation gear calls for shielded wiring drained through a resistor but only on one end, while others demand it and have a terminal for it.

__________________
If you let the smoke out, you void the warranty. - NK

mattsilkwood

Most generally if you have a digital signal you don't need a shielded cable, if you have an analog signal you do.

I will go so far as to say most of the time you can run an analog signal over a non-shielded cable and not have any issues.

I am seeing more and more equipment calling for shielded cable for everything, motors included. The reason being that a lot of new equipment is ran in cable tray and it will cut down on noise.

I had one machine that spec'd parallell 3 conductor 4/0 shielded for the main drive motor. I don't care if I never see a piece of that stuff again.

There was another contractor putting in a machine where I was at that had to install paralell 3 conductor 500 shielded. I felt sorry for that poor sob.

__________________
A man that will not read has no advantage over a man that can not read.-Mark Twain

Jamuz

Just remember, the trick with shielded cable is to ground only ONE end of the shield. I see alot of amateurs connect both ends and it defeats the purpose and causes ground loops.

Speedskater

A consultant and author, Henry W, Ott is probably the lead authority on this subject.
http://www.hottconsultants.com/
If you have a lot of time on your hands, you might read his new $100, 875 page book.

Depending on the situation and which expert you read, you might connect the shield:
a] At both ends.
b] At the source end, with a hybrid connection at the receive end.
c] At the source end only.
d] At neither end. (see above book)

CDN EC

I've seen it vary from Schneider Electric stuff (either do not use, or drain on either end with a 470K resistor), to Delta (terminate to specific terminal on both ends) to to TAC (don't use at all for networking) to Johnson (both ends at terminal (IIRC).

It's all HVAC control stuff so finicky at the best of times.

__________________
If you let the smoke out, you void the warranty. - NK

Ridge

Where I work the engineers designate it to cut down on noise, there are a lot of cable trays and I have used it in I/O drive cabinets and other I/O devices where there are a lot of signal wires going on with low voltage stuff. I've also used it to sheild 24v dc cat 5 from 110v signal wire in the same conduit. The cat 5 had neat rj45 ends with aluminum cladding.

Pinoysparky

What are the methods used to shielded a cable and what are the benefit?

CDN EC

Wrap it in tinfoil - a few layers per foot of cable should do, and take a picture of it with your hand visible and the name "Cletis" markered onto your palm.

__________________
If you let the smoke out, you void the warranty. - NK