Instrument Cable Tray

In the UK it doesn't matter provided the requisite creepage and clearance distances are maintained for Ex 'i' circuits, which will be the case if using SWA cables on the IS circuits, and appropriate segregation of the instrument cables from the power cables.

Unless there is some standard in the Client's documentation that hasn't been shared here?

Hi there,

I think you should re-look at your countries regulations regarding intrinsic safety.

First of all download the following:

www.crouse-hinds.com/CrouseHinds/resources/

intrinsically_safe/insafe.cfm

Intrinsically safe circuits may be wired in the same manner as

comparable circuits installed for unclassified locations with two

exceptions summarized as separation and identification. These

wiring practices are simple and clear; however, they often are

overlooked and are the source of potential problems.

The intrinsically safe conductors must be separated from all

other wiring by placing them in separate conduits or by a

separation of 2 inches of air space. Within an enclosure the

conductors can be separated by a grounded metal or insulated

partition.

Personally, I prefere to seperate IS and non-IS signals. In most cases, I end up with <1% of the total signals being non-IS. In cases like this - I make every signal IS. This prevents confusion arising as to what is IS and what is not. It also eliminates the possibility of the local maintenace crew connecting a IS signal to a non IS input.

Regards,

Craig

As referenced in the information by Craigza the only other add to your comment is that when a signal is IS it does not matter if it is analog in or out or digital in or out. they can be run together in the same tray without separation of the IS cabling. Only in cases where there is analog non incentive and discrete cabling (120 vac and Higher) require separation in most facilities. This to eliminate induction from the higher voltages to the analog and low voltage signals.