# Analog field sensors. Shielded field cables?



## Breakfasteatre (Sep 8, 2009)

Gentlemen,

I have several analog field sensors. temperature, pressure, etc.

I have shielded twisted pair cable to a local JB and the sensors were supplied, not by the manufacturer of the sensor, but by the customer, with a standard, 4 wire sensor cable, non shielded.

We are still a couple weeks away from powering up, and Im wondering if the sensor cable should be shielded as well.

what has been your experience? 

the sensors themselves have a m12 female connector on the sensor body


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## gpop (May 14, 2018)

Ive never had a problem with that type of set up


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## JRaef (Mar 23, 2009)

It depends a lot on the environment, as in the presence or absence of other interference producing equipment or wiring. For example if you have any VFDs, electronic ballasts, UPS systems, PCs or anything with power supplies near the instrument wiring, those devices produce EMI/RFI that will affect unshielded cables and if you have 480V cable near by, you can get induced voltages. But if you can keep your wiring away from those things, you can be perfectly fine.


Until someone later on mounts something next to it...


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## glen1971 (Oct 10, 2012)

Ensure that you terminate the shields on your wires and cables properly and that is about all you can do.. If it doesn't work right, you should be able to eliminate from the junction box back to the source..


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## MDShunk (Jan 7, 2007)

I exclusively use standard M12 cables for the final few feet to analog sensors of every sort, in proximity to VFD's and VFD controlled motors with zero ill effects. These are going to analog input cards of every vintage from 1990 to 2018. Matter of fact, when you construct Rosemount and Anderson-Negele sensor part numbers to include an M12 connector on the instrument, they supply an unshielded M12 cable. I really only deal with 4-20 and Hart, but I'm not sure what you're dealing with.


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## splatz (May 23, 2015)

In my experience knock on wood the 4-20ma sensors have been immune to interference as the literature promises. 

Also IME twisted pair has been pretty resistant to interference, either factory made twisted cable, or adding the twist in the field. 

Interference is occasionally a problem, but imagined interference problems are much more common than real ones.


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## gpop (May 14, 2018)

I would suggest you use something like silicon gel on the connector before plugging it in as 24vdc when damp likes to corrode the pins.


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