Cat5e for phone near Romex

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Joseph P.

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If you are snaking new Cat5e in a finished space that has Romex should you use shielded Cat5e so you don't get a 60hz buzz on the line if the phone wire comes in contact with Romex somewhere in the wall or ceiling?
- Do you have to ground the shielding foil for it to be effective or does the foil itself cut the field?
- + same question for Cat6 ethernet cable.
 
The shield will reduce electric field related interference whether it is grounded or not.
But it will not help much for the magnetic field.
Magnetic field interference will be reduced by the twisted pair design of the CAT5, and by keeping the cable away from the edges of the NM, where the field is strongest.

Tapatalk!
 
Baloney. If I had a choice I would maintain some parallel separation if the cable and Romex will be together for more than a few feet. But even with CAT3, in all my years I have never had a problem no matter how the cables were run.

Do you have to ground the shielding foil for it to be effective or does the foil itself cut the field? ... Same question for Cat6 ethernet cable.
Click to expand...

Do you even know that shielded CAT cables when used for data use special grounding plugs, jacks and patch panels? You don't just "ground" the shield. :happysad:

-Hal
 
It can't be a big deal...there is lots of non-metallic surface raceway installed with non-metallic dividers and data cables on one side of the divider and power wiring on the other side. The power and data are run parallel to each other with only a couple of inches of separation.
 
It is less of a big deal for digital signals on CAT5 than it is for analog phone signals on CAT5 where CAT4 is all that is needed.
As long as the audio circuit load is balanced, the twisted pair wiring should limit interference to an acceptable level.
But add imbalance, such as stray capacitance to ground on one wire of the pair only, or misidentification of which conductors form a pair and you will have trouble.

Tapatalk!
 
The electric field is directly linked to the magnetic field only in a photon. When we casually talk about radiated interference we are usually actually talking about near static E and M fields.
In that case the electric field is proportional to the voltage on the line while the magnetic field is proportional to the current.
Even a ferrous metal raceway does not provide as effective a shield for magnetic fields as it does for electric fields.

Tapatalk!
 
all depends on how much current is in the romex. low currents produce low mag field, etc.
also depends on the equipment connected to the cat wire. if its really sensitive then you might get noise issues, etc. lots of factors that play a role in the answer.

if worried, wrap the cat with mu-metal.
 
Joseph P. said:
If you are snaking new Cat5e in a finished space that has Romex should you use shielded Cat5e so you don't get a 60hz buzz on the line if the phone wire comes in contact with Romex somewhere in the wall or ceiling?
- Do you have to ground the shielding foil for it to be effective or does the foil itself cut the field?
- + same question for Cat6 ethernet cable.
Click to expand...

I have often run into a similar situation when fishing a wire in a finished wall for a telephone jack. Never even saw a hint of an issue with buzzing related to running parellel with Romex.
 
delectric123 said:
I have often run into a similar situation when fishing a wire in a finished wall for a telephone jack. Never even saw a hint of an issue with buzzing related to running parellel with Romex.
Click to expand...

the E/M coupling of wires will only be seen in very sensitive equipment. simply not enough gain in the generic electronics. something that uses opamp with say 1k gain, then maybe you'll start to see the noise, etc.
 
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