Instrument Junction Box segregation (ESD/PCS)

[aranoche]

Hi there,

I have problem at my instrumentation wiring from field to marshaling cabinets.
because of some trouble at detailed engineering, we should mix instruments that role as PCS and ESD to one JB with two multicable out. (of course it is out of client spec)
data i got are:
1. all instruments come out/in the JB are analogue, with same cable type.
2. two multipair cables out/in are each for ESD and PCS. (@ 12pair-1.5mm2)
3. there are two column of terminal blocks inside, one for ESD and one for PCS (@ 40 terminals)
attached is my wiring draft.
Is there any problem to system if i mixed this two?

regards,

 

[itsmoked]

While it's not a great idea because of future confusion/maintenance issues, it should be OK. Hopefully you can keep the grounds straight and not have ground loop issues where one instrument is grounded thru the other system.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Are you saying that this is a requirement of the client spec, or that it does not comply with the client spec?

It's not a great idea to combine the signals in one box unless there is some over-arching reason to do so. Why can you not provide two junction boxes? If we understand the reason for the need to route both groups of signals through one box then it would be easier to comment objectively.

 

[wafer71]

Good morning "aranoche".

Clients state the requirements for segregation for reasons such as ease of maintenance and overall awareness with respect to what I/O in a given JB is used for. Thus clients will do everything from use red or yellow lamicoids on the front of a JB with SIS on it as well. Part of the intiention for the segregation is so the homerun cable will be routed differently from conventional DCS I/O, however the problem with most plants today only one route is possible. Plot plans are getting smaller all the time, and equipment is getting squeezed. As well clients are looking at ways to build these green field facilities at a lower price without jeopordizing safety.

In the end it is up to the owner. Is segregation manditory? No.

 

[icewannabe]

Is there a problem installing additional JB?

Client requirement on signal segregation should be followed.