PE conductor in Instrument tray

[ctpt]

Hi all,

With reference to an offshore project (IEC design), please inform if it is allowed to run PE (Protective Earth)Conductor on an Instrumentation cable Tray. The electrical power system is a 415V solidly earthed. The installation is an Instrumentation Technical room where it is required to run the PE conductor and also Instrument earthing conductor (IE)for eathing various instrumentation, SCADA penels etc. But there is no dedicated electrical cable tray available.

Thanks,

 

[7anoter4]

In my opinion the grounding conductor of 415 V power cable has to run along the power cable and closely to this power cable. I don't see any reason to put a grounding cable in an instrument cable tray- I suppose a metallic cable tray, well covered and well grounding-at the ends and all 100-200 ft through the building grounding electrode, for instance. The grounding conductor will return the short-circuit current to transformer and may convey stray current even if no failure is declared.

 

[waross]

A little more information will help. Is it instruments or power equipment that is being grounded? What is the size of the grounding conductor? In the event of an earth fault, what is the largest breaker that may trip, and what is the largest earth fault current that may be expected?


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ctpt]

Bill,

The grounding conductor is for grounding Instrument equipment (DCS, Fire & Fas Panel etc.).

Actually, a single core, 70 sq.mm. cable (EPR Insulated) runs across the room. Individual grounding conductor (16 sq.mm, EPR )from each Inst. Equipment is connected to this 70 sq.mm. cable.

A largest breaker that may trip in the event of earth fault is 32 Amps.

Now, could this 70 sq.mm grounding cable be run on the Instrument tray together with other Instrument cables?