shielding in conductors

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charlie b

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Please stop asking us to do your homework for you. Tell us what you think the answer is, and let us take it from there.
 
this isnt my homework. I have about 25 questions that i was studying for an optional test and there were about 4 i was unsure of. but i do appreciate your response. by the way, i think they come sheilded @ 600 volts.
 

Smart $

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this isnt my homework. I have about 25 questions that i was studying for an optional test and there were about 4 i was unsure of. but i do appreciate your response. by the way, i think they come sheilded @ 600 volts.
Shielded conductors are manufacturered at most all voltage ratings. Mostly what separates them is the type of shielding being referred to, such as shielded single conductor, [twisted-] pair, triplex, quadplex, etc. and the common sizes.
 

steve66

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Shielded conductors are manufacturered at most all voltage ratings. Mostly what separates them is the type of shielding being referred to, such as shielded single conductor, [twisted-] pair, triplex, quadplex, etc. and the common sizes.


Agreed, but if your study question is more like "At what voltage are shielded conductors required?", then I think you will find your answer in Article 310.

Steve
 
at what voltage do wires come shielded?

II. Installation​
310.10 Uses Permitted.
......
(E) Shielding.​
Non-shielded, ozone-resistant insulated conductors with a maximum phase-to-phase voltage of 5000 volts shall be permitted in Type MC cables in industrial establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation. For other establishments, solid dielectric insulated conductors operated above 2000 volts in permanent installations shall have ozone-resistant insulation and shall be shielded. All metallic insulation shields shall be connected to a grounding electrode conductor, a grounding busbar, an equipment grounding conductor, or a grounding electrode.

 

Smart $

Esteemed Member
Location
Ohio
Agreed, but if your study question is more like "At what voltage are shielded conductors required?", then I think you will find your answer in Article 310.

Steve
Yes. Adding or changing words can make a BIG difference...!!!
 
Yes. Adding or changing words can make a BIG difference...!!!

Yes, but that is not the problem in this case.

The problem in this case that the same word is used for two functionally distinctly different construction. Ones functionality is to control voltage stress phenomena that exist at all voltage levels but causes problems only above certain voltage levels, and the other is used to mitigate EM and RF interference with low power signal wiring.
 

Smart $

Esteemed Member
Location
Ohio
Yes, but that is not the problem in this case.

The problem in this case that the same word is used for two functionally distinctly different construction. Ones functionality is to control voltage stress phenomena that exist at all voltage levels but causes problems only above certain voltage levels, and the other is used to mitigate EM and RF interference with low power signal wiring.
I must need special glasses to read and get what you're saying out of the OP ;)
 

gar

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Location
Ann Arbor, Michigan
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EE
101118-2343 EST

I probably need electrostatically shield cables for a microphone, or a straingage transducer, or EKG work, and many other low level signals.

May need them to minimize radiated EMI.

.
 

gar

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Location
Ann Arbor, Michigan
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EE
101119-0930 EST

weressl:

What is a microphone cable but a cable? The word cable is used in a lot of ways.

An electostatic shielded, by this I am referring to a conductive type shield vs a magnetic material shield, does reduce EMI transfer from within to outside, or outside to within. Its effectiveness will vary with shield design, geometry, and frequency.

If I make an antenna with a single copper wire 25 ft above ground and 100 ft long parallel to ground and connect this to the non-ground input of an AM radio (550 - 1600 KC), earth to the radio ground terminal, then I will get pretty good AM reception. This was what was done in the old days when transmitter power was low, and maybe the receiver was a crystal set.

Now replace the antenna wire with a coaxial cable or even Belden 8723. Connect the shield or drain wire to the radio ground terminal and still keep the radio connected to earth. Connect all wires within the shield to the radio's non-grounded input, then reception will be next to non-existent.

.
 

rattus

Senior Member
Fwiw:

Fwiw:

Once I was making leakage currents in microamps with shielded cable, but the tech had not connected the shields to ground. Corrected that omission, and we were measuring picoamps!
 
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