Instrumentation Install

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gregwaits

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Hi,
I am looking for advice on the most economical way to get cable to instruments in the field from the I/O to a Marshalling cab to the devices.

I am thinking a combination of cable tray and conduit with flex to the devices. I am also thinking of MC cable for everything with TMCX connectors.

I think piping all the way is the most expensive.

Thanks for any help.

regards

GW
 
Most marshaling cabinets I have seen use cable tray for the main artery runs separate from high and low voltage then branch out from cable tray in pipe to flex to device. How many devices andhow long are the runs??
 
Cable tray would be my choice.Its the most common wiring method in the world, less so in the US.
I would use PLTC for the instruments. TC for power. Conduit from tray to devices with LT conduit.
Assuming this is not a classifed location.
 
Bump?

Bump?

Hi,
thanks for the replies. I apprecate the comments. This is pretty much what I was figuring on..

There are some classified areas involved.

I do not know what "Bump" means.

Thanks

GW
 
If you do the TMCX 's (very efficient by the way even at 45 minutes per termination for packing), make sure you order some extra "icky puck" (epoxy compound) packs, and that they don't freeze.
 
What exactly is the purpose of the marshalling cabinet other than to introduce an (possibly) unneeded splice into the system. I not knocking your question, just curious about what benefit a marshalling cabinet brings to the system.

Why not go from I/O cabinet-to-cable tray-to-conduit-to-flex-to-instrument? Is there a code rule that prohibits the cable from being installed directly into the conduit? If it's for instrumentation the wire will need to be shielded and that means a cable.
 
Marshalling Cab

Marshalling Cab

Hi,
Thanks for all the replies. I am inheriting a system install. The engineer before me put these marshalling cabinets in.

Why not go from I/O cabinet-to-cable tray-to-conduit-to-flex-to-instrument?
This my desired method.

There are about 4500 instruments.

The plan now is to PIPE everything then flex to instrument.

The company is trying to save some money on labor.

thanks

GW
 
Marshalling cabinets

Marshalling cabinets

Hi,
I forgot to add that these marshalling cabinets are placed strategically in the field to connect the field devices to the I/O.

It seems to be an economical way of doing it and providing room for future expansion.

Thanks

GW
 
I realize you are not the engineer or designer, but have they thought about remote I/O panels, DeviceNet, etc? Instead of a marshalling cabinet make it a remote I/O cabinet or DeviceNet drop. Any of those methods would cut down on the amount of pipe and wire required.
 
gregwaits said:
I do not know what "Bump" means.
Click to expand...

Bump simply means I'm pushing your thread to the top of the heap. You posted your thread at 9AM and had no responses at 5PM. Some times you need to throw a thread out to the evening guys, weekend guys, ect.

EDIT: What Jim said.
 
I did a DDC system in a multi phase project a few years ago. It was spec'd out in such a way that all the control wiring had to be in conduit. Wrapping pipe around air handling units to all the controls gets a bit crazy, buy lots of fittings and boxes and flex, or better yet, seal tight looks better than flex imo.
We grouped a lot of the i/o boards together because the engineering on the distribution of points on the i/o boards wasn't the best so it actually made it a bit easier for us. It made the final testing of the units a lot easier too.
 
Device Net

Device Net

Hi,
Yeah wireman that sounds very interesting. Could you elaborate a little more?

I am not the engineer but the construction manager.

I am also a Master Electrician.

I have not installed any of the field wiring as of yet so I am looking for the latest most innovative way to go..

Thanks

GW
 
Bump explained...

Bump explained...

Thanks guys...

I am new to the site and not too familiar with some of the slang.

Thanks for explaining it to me.

regards

GW
 
I have done several projects where we set distribution panels in the field and pulled 44 pair shielded and 36 conductor # 14 type TC cable to them. All of the wires were numbered and terminated during the initial phase. This allowed us to come back and add or alter instrumentation and controls with very little labor.
 
gregwaits said:
Hi,
Yeah wireman that sounds very interesting. Could you elaborate a little more?

I am not the engineer but the construction manager.

I am also a Master Electrician.

I have not installed any of the field wiring as of yet so I am looking for the latest most innovative way to go..

Thanks

GW
Click to expand...

First a question: Is this a PLC system? If so, then the PLC's processor will be in one location (panel) with some I/O modules for devices closest to that panel.

Remote I/O panels are then connected to the processor by a shielded cable using a specific comm format for that PLC. Most PLC's support more than one remote I/O drop, so you could have several of these R-I/O panels scattered throughout the area and individual instruments, solenoids, switches, etc. only need to be wired back to the nearest R-I/O panel. The distance allowed from the processor to a remote I/O panels varies, but it is up to the hundreds or sometimes thousands of feet.

Devicenet is a little complicated to explain here but google it and you'll find some helpful tips about laying out a Devicenet system. The end result is that you will run less conduit and wire than with a marshalling cabinet and possibly R-I/O.

Many DCS systems have similar schemes as PLC's and remote I/O panels. They just may name it something else.
 
Field Locations

Field Locations

They are claiming that they have had a lot of problems in the past from folks opening the cabinets and letting them get dirty and left open...

it looks as if I will go with cable tray, pipe, then flex...

we used to use tray cable all the way to an instrument without sealtite in unclassified areas...we just used cgb's on the intrument...

this job has some packaged skids which come with PLC's and I/O racks to boot.

The replies so far have been great. Thanks again...

GW
 
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