CAT-5 Stat Wire?

[Big Unit]

I'm just curious as to why some manufacturers recommend using 3 wires out of a CAT-5 for their remote sensors instead of the standard 20 or 22 gage.

[xarralu]

I'm just curious as to why some manufacturers recommend using 3 wires out of a CAT-5 for their remote sensors instead of the standard 20 or 22 gage.

Thats weird. Where did you see that at?

[air2spare]

I'm just curious as to why some manufacturers recommend using 3 wires out of a CAT-5 for their remote sensors instead of the standard 20 or 22 gage.

probably due to shielding thats in the wire jacket, it keeps interference out of the communicating signals

[D1G]

There are many flavors of shielded twisted pair cabling. CAT-5 or better is probably specified to ensure sufficient twists per unit length.

One pair for signal and one conductor for ground. If that's not specified there's no point in specifying the use of 3 conductors of a CAT-5 cable unless it's just a CYA issue. That is, they don't want people to use the cheapest of the bare minimum which could cause problems so they spec the higher grade cable to cut down on hits to their tech support.

[Big Unit]

Thanks for clarifying.

Thats weird. Where did you see that at?

I want to say that it was a Carrier install, but i'm not 100% sure.

[Cagey57]

I have 2 guesses:

1. CAT5 is relatively common from most cable/wire suppliers and most people that run cabling won't cut a CAT5 cable.

2. Spare wires baby, spare wires ! If ya run a CAT5 that has 4 twisted pair and you only use 3 that leaves.... wait, let me get my calculator...... 5 spare wires. (I don't know but that's my guess)

[zinc22]

Still.....CAT5 is a real pain in the........to work with for regular screw terminal wiring.

My 2 cents

[chilliwilly]

Yes this is something that I have noticed over the past few years not just in voice and data, but also in basic circuits like stats/sensors, fire alarms, intruder alarms, and CCTV (baluns systems).

I've also heard that there is an international harmonisation document somewhere, you know the kind I mean. It's kept in a vault in an impregnable underground bunker, in a secret location under secured armed guard and surrounded by mine fields and genetically modified man eating dickheads (area 57).

And nobody is allowed to look at it unless your surname has at least 25 letters after it and appears in the lists of acknowledgements that appear in all electrical wiring regulations and electrical codes around the world.

It states that "CAT V" will be the minimum standard for signaling and for low to medium speed coms in the future. So if you wire low power controls in screened "CAT V," you won't have to rewire it in the future if and when the sensors and everything else have more gubbins inside them, and probably won't work unless they are connected to "CAT V"!

[Big Unit]

Yes this is something that I have noticed over the past few years not just in voice and data, but also in basic circuits like stats/sensors, fire alarms, intruder alarms, and CCTV (baluns systems).

I've also heard that there is an international harmonisation document somewhere, you know the kind I mean. It's kept in a vault in an impregnable underground bunker, in a secret location under secured armed guard and surrounded by mine fields and genetically modified man eating dickheads (area 57).

And nobody is allowed to look at it unless your surname has at least 25 letters after it and appears in the lists of acknowledgements that appear in all electrical wiring regulations and electrical codes around the world.

It states that "CAT V" will be the minimum standard for signaling and for low to medium speed coms in the future. So if you wire low power controls in screened "CAT V," you won't have to rewire it in the future if and when the sensors and everything else have more gubbins inside them, and probably won't work unless they are connected to "CAT V"!

Not big on CAT-5 for everything! Could this possibly be just in England?

[durussel78]

Last question - RFI.
Big thing in commercial other problem is running to close to high voltage with comm line the EMF screws with the signals.
I believe that they manufactured comm5 - 8 or 7 was just that manufacturing. Cheaping to build and more expensive to sell but a mandatory sell because everything calls for it.

[chilliwilly]

Last question - RFI.
Big thing in commercial other problem is running to close to high voltage with comm line the EMF screws with the signals.
I believe that they manufactured comm5 - 8 or 7 was just that manufacturing. Cheaping to build and more expensive to sell but a mandatory sell because everything calls for it.

I'm not trying to teach anyone to suck eggs but just in case you don't know, to prevent this you would have to segregate the circuits and allow at least 2" (50mm) of space between band 1 and band 2 circuits. (<50 volts, >50 volts).

Better still, run screened/sheilded "CAT V" so that where it enters any part of the system enclosure it still has segregation. If any transients are induced onto the internal cores and cause the signal voltage to rise, the action of the twisted pairs will in turn induce the same voltage increase on it's adjacent core. And in turn will maintain the signal integrety if the signal is modulated.

Just my tuppence ha'penny of thoughts.

[chilliwilly]

Not big on CAT-5 for everything! Could this possibly be just in England?

I've even seen it on commercial washing machines as a coms link between the main board and the invertor, with all the cores connected?

The older machines just have a belden screened 2 pair, but if you need to replace the invertor you need to install an upgrade kit so the new invertor can interface the existing main board.

[osiyo]

I'm not trying to teach anyone to suck eggs but just in case you don't know, to prevent this you would have to segregate the circuits and allow at least 2" (50mm) of space between band 1 and band 2 circuits. (<50 volts, >50 volts).

Better still, run screened/sheilded "CAT V" so that where it enters any part of the system enclosure it still has segregation. If any transients are induced onto the internal cores and cause the signal voltage to rise, the action of the twisted pairs will in turn induce the same voltage increase on it's adjacent core. And in turn will maintain the signal integrety if the signal is modulated.

Just my tuppence ha'penny of thoughts.

All essentially true, close enough.

Cat V specified for a stat is pretty much overkill. But what the heck? Why not? Saves the manufacturer from having to look up the specs on this or that cabling and then listing a bunch of "suggested" types of cable. As some do. And Cat V is readily available most anywhere.

I know that one of our system designers, who specializes in a line of controls I don't deal with, always specifies Cat V to be pulled to digital stats, even when the stats are simple ones that just require 2 conductors. His basic philosophy on the subject is that the Cat V will meet requirements, and as far as the extra conductors they could come in handy later if the customer wishes to upgrade the stat to one with more features that might require additional conductors.

Chuckle, a man after my own heart. I always have my installers pull some spare cables on any run that's significantly long or difficult.