Cable routing: Cable trays vs Power poles distribution

[wsbeih]

I'm working on a design of cable routing in a project within a water treatment facility. My suggested design is based on having tray routing (12"x6") Aluminum trays (one for power and one for Instrumentation), ~3000 foot total length.

The client has recently suggested to consider Power pole distribution for power and instrumentation cables instead of trays. Space wise, no issues.
However, for me this is unsafe installation in a facility due to many obvious reasons. But I'm not sure about the cost of such installation. This project is cost driven!

I seek the experts' opinions/thoughts to be able to provide their input about this installation from Safety and cost perspective!

Thanks in advance!

 

[gray.one]

What is wrong with safety?


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[gadfly56]

I'm having trouble visualizing this. Are the poles and trays indoors or outdoors??

 

[Ingenieur]

qty and size of cond/cables in each tray?
power feeders to pnls or motors?
are the control cables one for each instrument/control point or a comm link/addressable?
cable schedule?

 

[Julius Right]

If you have how to support 137 kg/m[20lbs/ft.] all 10 ft. for 3000 ft. the cable tray could be a less expensive solution. If you have not you have to install 300 poles in order to support the cable tray.
A catenary suspension for each power cable and for a bunch of instrument cables could be less expensive.[less poles-all 100 ft. one then only total 30]. The cable length will be- any way -20-30% longer and the pole higher. However, you have to cover the cables against sun radiation. See for instance:
http://www.cooperindustries.com/content/public/en/b-line/products/cable_tray_systems.html
and
http://www.dalekovod-proizvodnja.com/EasyEdit/UserFiles/pdf/kontaktne-mreze-hr.pdf

 

[wsbeih]

I am trying to route the followings:
4 MV cables (3/C 2/0 +G) each
2 LV cables (3/C 2/0+G) each
3 circuits for some lighting/small power.
Bulk of Instrumentation/control wires to JB's around the plant.

This is outdoor installation. There is currently overhead distribution (wooden treated poles) in the plan, but for MV main distribution and small lighting circuits, CCTV, etc.

My notes:
1- I have never designed overhead distribution for this munch of multi conductor cables.
2- I believe overhead distribution in a plant facility is not safe practice where you have people and personnel working/driving, cranes, all the time around.

 

[Julius Right]

For such a busy area may be a cable duct bank will be better. However it is very expensive and it should clear the way in order to dig the trench.
An overhead system has to be cheaper.

 

[gadfly56]

I am trying to route the followings:
4 MV cables (3/C 2/0 +G) each
2 LV cables (3/C 2/0+G) each
3 circuits for some lighting/small power.
Bulk of Instrumentation/control wires to JB's around the plant.

This is outdoor installation. There is currently overhead distribution (wooden treated poles) in the plan, but for MV main distribution and small lighting circuits, CCTV, etc.

My notes:
1- I have never designed overhead distribution for this munch of multi conductor cables.
2- I believe overhead distribution in a plant facility is not safe practice where you have people and personnel working/driving, cranes, all the time around.

How is cable tray going to be any less a collision target than overhead cable?

 

[Phil Corso]

... 137 kg/m[20lbs/ft.]...

Julius, regardless of your last name, in this case you ain't Right! 137 kg/mt equals ~ 92 lbs/ft!

Phil

 

[wsbeih]

Let me add one more question for the experts out there:

Have you seen such distribution for multi-conductor cables for MV, LV and I&C Feeders distributed on wooden poles?
Is this a normal practice?

I know it is common for transmission, and main power sources only, but not feeders!

Thanks in advance!

 

[gray.one]

Let me add one more question for the experts out there:

Have you seen such distribution for multi-conductor cables for MV, LV and I&C Feeders distributed on wooden poles?
Is this a normal practice?

I know it is common for transmission, and main power sources only, but not feeders!

Thanks in advance!

We've done this in an industrial plant before (outdoors).


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[Fnewman]

Let me add one more question for the experts out there:

Have you seen such distribution for multi-conductor cables for MV, LV and I&C Feeders distributed on wooden poles?
Is this a normal practice?

I know it is common for transmission, and main power sources only, but not feeders!

Thanks in advance!

Have seen this type of construction in industrial settings many times at voltage levels up to 15 kV. Never heard of problem other than a pole being struck by a vehicle, but that would be a problem with any above-ground method. Properly selected cable suspended from properly designed messenger cable is not unsafe, in my opinion. It will likely be significantly less expensive than cable tray because of the tray's support requirements.

 

[Julius Right]

Thank you Phil. My mistake indeed!:ashamed1: