4-20 mA and power 230 ac wiring in the same duct

Hi,

Is it allowable to lay down analog wiring and power 230 ac wiring in the same plastic duct or adjoining parallel ducts within control cabinet?

There are strong requirements to segregate instrument and power cables but what about wiring within the cabinet? The maximum lenght of mixed wiring is 500 mm in my case.

4 to 20ma is not so bad however i never run o to 10v in the same duct

In general inside panels the AC and analog wiring are run in parallel and adjacent wire duct, and to the extent possible wires crossing through one duct from another should do so at right angles. I haven't had any problems following this practice, but most of my panels are 120 VAC, not 230 VAC.

I try to put any three phase power wire in a separate portion of the enclosure for both EMR/RFI considerations and safety reasons. I am assuming your 230 VAC is 50 Hz single phase. You should be OK with the above. However, most European panels I've seen use 24 VDC for all discrete I/O and so have minimal 230/1/50 wiring to contend with.

"Within a control cabinet" is a special condition, since it is a termination point for diverse wiring. The rules for raceways can't always be maintained within a control cabinet. Still, it is best practice to maintain power and signal wire separation to the greatest extent possible. That being said, there is quite a significant difference between lightly loaded I/O wiring and actual power wiring. I'd be particularly careful with any AC circuits that have a potential to draw high amperage.

With a length of 500mm you won't have any problem, that is not a long enough distance for crosstalk at 50/60 hz.

However, as a good practice your 4-20mA wire should be shielded twisted pair.

All wiring in a duct should have insulation that is rated for the highest voltage present in the duct. Highest voltage is rated peak to peak, not RMS, so for 230V all wire in the duct should have insulation rated 300V or better.


Edit, just noticed your location. If your 230V is derived from a single leg of Y380/400 to neutral as opposed to a transformer then make sure the insulation rating of all the wires is 500V or better.

(As always, follow local codes over advice on the internet from some guy half way around the world )