Power Cable in IS Cable Tray Inside Cabinet

Vendor Siemens guys have complained that the Governor Control cabinets have IS cables in blue cable trays and along with it we have a 24 VDC 2 wire cable entering in it. Is it Ok? do we need sheathed screened 24vdc cables?

My experience has been yes, you will need shielded cable.

IS and 24VDC cable should also be separated within the tray. Simply put, do not bundle the IS and 24VDC cables together.

Have you contacted your Siemens rep regarding this issue?

The IS must be hypersensitive to those big ol' 24vdc signals, so indeed this is an issue of cable allergy.

5¢ please.

--Lucy Van Pelt Psychiatric Advice

"Governor Control cabinets have IS cables in blue cable trays"

Any first year cable tech knows not to run IS cables in blue cable trays. It throws the power factor off by multiples of 11.

Provided the cable and its terminations comply with the creepage and clearance parameters in BS5345 and its successors' Ex i section, then there won't be a problem.

Is it Ok?

Possibly, but only if a minimum separation distance is maintained between Intrinsically safe and non intrinsically safe cables and only if the electrical and hazardous area standards applicable to your site, and country allow it to be run in the same cable tray (requirements vary from country to country and can vary from application to application).

Guessing based on the information given it looks like a standards issue. I think the Siemens vendor perhaps has called into question the use of a non-intrinsically safe cable being used in a blue cable tray designated exclusively for "intrinsically safe circuits only".

Have a look at your applicable electrical standards. Screening the non-intrinsically safe cable may not be allowed, you may need to run it in a completely different cable tray, etc.

Let us know what you find.