[FUN] Cable Tray question

[Stephen Mitschke]

Is there a published spec or any user experience with running FoundationFieldbus Type A style cable (4 pair individual shield and cable overallshield) in a cable tray next to 120 VAC heat tracing wiring?As the heat tracing switches on/off, I would expect the possibility of somegenerated 'noise'. There is good engineering practice however, I am lookingfor something either written or some users experience that helps justify the'good practice'Appreciate all replies.Thank-youGlennFoxboro

[Stephen Mitschke]

I believe that I installed the cables in the same tray as the powerbearing in mind that all the cables had armour and that the insulationratings were the same. This was done at Gold Bar Wastewater TreatmnetPlant and I have not heard if they have had any problems. I had appliedthe same reasoning as the CEC for different voltages.Barry LundinTelematic

[Stephen Mitschke]

Glenn,Good Engineering Practice -Good engineering practice is to run them separately from ac loads,segregatedby at least 1m. The FF standards installation manuals give guidance onthis.If however you want to bend the rules a little, here is our experience -On the Filter Test Rig at BNFL Springfields we deliberately ran the H1cabling on the same tray and trunkings as devices such as 400v, 3-phasemotors and 110v solenoid valves. We have done no EMC measurements butneitherhave we experienced any EMC related problems in our H1 circuits. Thisindicates to us that FF is quite robust in EMC rejection problems.FF is capable of rejecting EMC corrupted messages. If the trace heatingswitch cycle rate is low, the odd missed data packet may not matter thatmuch.If you do get a problem -The H1 cable you describe seems very well shielded. Although it will lookcheap and nasty you can improve the shielding effects by simply runningit onthe outside of the cable tray as the intervening metalwork if the trayitself gives a surprising amount of additional screening.regardsTom NobesBNFL