twisted triad vs twisted pair

[buzzp]

Our electrician wants to use twisted, shielded triad (3 conductor) wire for an analog signal (4-20mA). I specified twisted pair, shielded but the question has been posed to me. My instinct says this will not perform as well as a twisted pair because the opposing magnetic fields of the two wires will not be 180 degrees apart due to the extra conductor in the twist.

Anyone try this before? Any feedback?

 

[IRstuff]

What does that 3rd conductor carry? The issue, seems to me, is that the 3rd conductor needs to be grounded, which means that you wires will see that much more capacitive load.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[buzzp]

Thats the problem, the third conductor is not needed and leaving it floating or grounding seems counter intuitive.

 

[IRstuff]

Floating is bad, period. Grounding would be preferred to floating, by far.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[buzzp]

I will make them use what I specified.
Thanks IR.