Shielded or Not?

Projects General Guidance
1

I have 3 40 pin cables running from a control board to an input panel. Most of these lines are sensor wires ... the ones that are not carry very low end 5v power to switch relays on and off.

I have a 1000ft long 25 pair telecommunications cable which would work perfectly to make these connectors ... each wire is insulated but they are not shielded ... is there any need for shielded cables (I don't have them anywhere else)

Thanks for the help!

2

"Telecommunications cable" is likely twisted-pair. If all your connections through this cable are balanced current signals, then shielding is not necessary. (eg. a 4-20mA sensor or RS485.) If you run a power wire, or Serial or just a button, then you're working with voltages which will not be protected by the twisted pair. Then you might consider a shielded cable.

3

Be sure to match the pairs by their color. They will be twisted. All should be ok.

Paul

4

They don't look to be twisted ... also they are surrounded in a powder coating with what looks to be white frayed string

They are not all the same signal wires ... but the first 5ft or so on either end that travel between the input panel and its connector and the control board and its connector are made up of regular 22 gauge wire from radio shack

Some wires are 5v inputs to relays some are signals to and from sensors and some are power wires ... I think I need to go through and do a serious redesign as some wires should be larger gauge than others

I'll send in pictures tomorrow ... thanks

5

FrankyMonez:
They don't look to be twisted ... also they are surrounded in a powder coating with what looks to be white frayed string

They are not all the same signal wires ... but the first 5ft or so on either end that travel between the input panel and its connector and the control board and its connector are made up of regular 22 gauge wire from radio shack

Some wires are 5v inputs to relays some are signals to and from sensors and some are power wires ... I think I need to go through and do a serious redesign as some wires should be larger gauge than others

I'll send in pictures tomorrow ... thanks

Pictures are good! Certainly not standard telephone/communications wire. They all have standard color coding so pairs can be kept together.

Paul