# Need Opinions



## dawgs (Dec 1, 2007)

I am looking at a job in an incinerator plant. THIS PLACE IS NASTY! Anyway the job consists of replacing about 200' of cable tray. The existing tray is rusted out from the burnt ash and cables are covered in ash. Most of the cables are instrumentation and control but one tray has 8 sets of about 350 mcm power cables in it. The engineer says all work needs to be done while they are on line. Im not comfortable installing temporary supports for those cable runs while they are hot. We will clean off the cables and inspect them prior to moving them around. Would anybody else work with these hot?


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## wildleg (Apr 12, 2009)

depends on the condition of the cables (you didn't mention the voltage but I am guessing 480). it may be possible to devise a safe system for handling (or not). If it's not, don't do it.


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## MDShunk (Jan 7, 2007)

If the cable tray is hung off something, I'm pretty sure you can devise something to temporarily hang the installed cables. Maybe work just a couple sections at a time? 

What's the chances that the new tray is any wider than the old? I'm thinking install the new right under the old, and lower the cables into the new tray as you demo the old? 

I'm not a huge fan of this whole idea, but I'm sure you can pull it off if you inspect the cable visually before you mess with it. I know ash is caustic, but it probably didn't screw with the insulation on the conductors much at all.


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## Zog (Apr 15, 2009)

dawgs said:


> I am looking at a job in an incinerator plant. THIS PLACE IS NASTY! Anyway the job consists of replacing about 200' of cable tray. The existing tray is rusted out from the burnt ash and cables are covered in ash. Most of the cables are instrumentation and control but one tray has 8 sets of about 350 mcm power cables in it. The engineer says all work needs to be done while they are on line. Im not comfortable installing temporary supports for those cable runs while they are hot. We will clean off the cables and inspect them prior to moving them around. Would anybody else work with these hot?


If I recall that is a task specifically listed in the 70E tables and therefore considered an "interaction" that could cause an arc flash event. So you need to justify doing them hot, have the engineer sign off on your EEWP and wear PPE to do this task. I bet he won't sign it and changes his mind.


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## dawgs (Dec 1, 2007)

The conductors are about 25 years old. The tray is all ate up. Non existant in some spots. We are going to replace with either fiberglass or stainless. I was thinking they could wear hot gloves while working with cables. Also the temperature up there will most likely be over 100deg. They will also be wearing respirators. Not a very good job.


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## MDShunk (Jan 7, 2007)

dawgs said:


> The conductors are about 25 years old. The tray is all ate up. Non existant in some spots. We are going to replace with either fiberglass or stainless. I was thinking they could wear hot gloves while working with cables. Also the temperature up there will most likely be over 100deg. They will also be wearing respirators. Not a very good job.


Oh, man. No matter how you look it this, that sounds like a really sucky job. Probably only 3 hours of productive work in an 8 hour day, with taking cooling breaks and such.


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## Southeast Power (Jan 18, 2009)

I would vacuum the cables and find out if I could at least meg the 350s before I started.
What elevation are the trays?


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## dawgs (Dec 1, 2007)

MDShunk said:


> Oh, man. No matter how you look it this, that sounds like a really sucky job. Probably only 3 hours of productive work in an 8 hour day, with taking cooling breaks and such.


Yea were just giving a budgetary price, the job will be T&M. Its by far the nastiest job we have been involved in.


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## dawgs (Dec 1, 2007)

jrannis said:


> I would vacuum the cables and find out if I could at least meg the 350s before I started.
> What elevation are the trays?


I wish we could the plant runs 24-7.


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## slickvic277 (Feb 5, 2009)

Depending upon the amount of "ash'' and it's make up you could be walking into a ticking time bomb. Is this a classified hazardous location? House keeping might be an issue with this place. I would think twice before doing any work energized in this place.


Maybe Zog will have more insight into this situation.


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## dawgs (Dec 1, 2007)

slickvic277 said:


> Depending upon the amount of "ash'' and it's make up you could be walking into a ticking time bomb. Is this a classified hazardous location? House keeping might be an issue with this place. I would think twice before doing any work energized in this place.
> 
> 
> Maybe Zog will have more insight into this situation.


They dont have it as classified. Its in clean up repair mode now, many years of not being kept up. It was just bought out and now they are spending a ton of money to get it right. This is our first job there and could lead into a lot of work for us, and put some guys back to work.


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## MDShunk (Jan 7, 2007)

dawgs said:


> They dont have it as classified. Its in clean up repair mode now, many years of not being kept up. It was just bought out and now they are spending a ton of money to get it right. This is our first job there and could lead into a lot of work for us, and put some guys back to work.


That's pretty motivating.


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## NEVERLATE (Jul 25, 2010)

Here is the way I see it. Regardless of what you are getting paid to replace the cable tray, it isn't going to be enough to cover the cost of replacing all the cables if something happens. I have little doubt that IF something happens to the cables while the tray is being replaced, the customer is going to look to you or your insurance company for the cost of repair and lost production. In my mind, there is no decision to be made. The customer takes a shutdown or I don't do the work. 

There are alot of variables here but here is how I see it being done. Run new cable tray and install new conductors without disturbing the old ones. Take a short plant shutdown 10-15 hrs and switch over to the new cables. Once the switch has been made, demo the old cable tray and cables.


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## dawgs (Dec 1, 2007)

NEVERLATE said:


> Here is the way I see it. Regardless of what you are getting paid to replace the cable tray, it isn't going to be enough to cover the cost of replacing all the cables if something happens. I have little doubt that IF something happens to the cables while the tray is being replaced, the customer is going to look to you or your insurance company for the cost of repair and lost production. In my mind, there is no decision to be made. The customer takes a shutdown or I don't do the work.
> 
> There are alot of variables here but here is how I see it being done. Run new cable tray and install new conductors without disturbing the old ones. Take a short plant shutdown 10-15 hrs and switch over to the new cables. Once the switch has been made, demo the old cable tray and cables.


Well there are hundres or control cables so thats not an option and the customer will know that we wont be responsible I will make sure of that.


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## MDShunk (Jan 7, 2007)

I don't think you have much to worry about with regard to the control cables, but the 480 feeders worry me some. There even much slack in this tray to help you out?


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## NEVERLATE (Jul 25, 2010)

dawgs said:


> Well there are hundres or control cables so thats not an option and the customer will know that we wont be responsible I will make sure of that.


 
That then, just leaves the safety issue at hand. Me, I'm not touching them especially if they haven't had a insulation test. Good luck with it. I say push back on the customer on this one. There are 2 types of plant shutdowns, scheduled and unscheduled. Which one do you think they would prefer?


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## MDShunk (Jan 7, 2007)

I thought that all incinerator plants took regular scheduled shutdowns for the boilermakers to do PM work?


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## oldtimer (Jun 10, 2010)

Blow the residue off the cables and tray.

Give them a good visual inspection. 

If cables are safe, hang some temporary support, Unistrut or whatever.

Hang cables on temp supports.

Remove and replace one section of cable tray at a time. 

P I T A, but if cables are in good condition, it will be worthwhile.


B T W, what kind of cables are they? Armored, pvc jacketed armored?


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## MDShunk (Jan 7, 2007)

oldtimer said:


> B T W, what kind of cables are they? Armored, pvc jacketed armored?


I've got money on THHN or RHW.


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## NEVERLATE (Jul 25, 2010)

oldtimer said:


> Blow the residue off the cables and tray.
> 
> Give them a good visual inspection.
> 
> ...


 
Eyeballs won't tell you if the cable is in good condition. A megger and a hipot on the other hand will. 350KCmil 25 yrs old in an incenerator plant, carrying current? No thanks.


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## dawgs (Dec 1, 2007)

Yea I am going to push for some down time for the feeder cables portion.


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## oldtimer (Jun 10, 2010)

I M O, it's still a good idea to visually inspect. The residue may not be as damaging as you think. When I used to work at an iron ore mine, the cable trays in the Pellet Plant had to be blown off regularly. That was iron ore dust!

Another potential problem was, the cables couldn't dissipate heat as freely when thy were covered with dust, and the dust played hell with the contactors of the overhead crane.


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## MDShunk (Jan 7, 2007)

oldtimer said:


> Another potential problem was, the cables couldn't dissipate heat as freely when thy were covered with dust, and the dust played hell with the contactors of the overhead crane.


What's the fix for that? Tear the contactor apart and clean it with 2-26? Replace it? Sounds like a heck of a thing.


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## oldtimer (Jun 10, 2010)

MDShunk said:


> What's the fix for that? Tear the contactor apart and clean it with 2-26? Replace it? Sounds like a heck of a thing.


 We would lock out the power feeds, remove the covers of the contactors etc, and blow them out. A real dirty, dusty job.


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## Shorty Circuit (Jun 26, 2010)

dawgs said:


> I am looking at a job in an incinerator plant. THIS PLACE IS NASTY! Anyway the job consists of replacing about 200' of cable tray. The existing tray is rusted out from the burnt ash and cables are covered in ash. Most of the cables are instrumentation and control but one tray has 8 sets of about 350 mcm power cables in it. The engineer says all work needs to be done while they are on line. Im not comfortable installing temporary supports for those cable runs while they are hot. We will clean off the cables and inspect them prior to moving them around. Would anybody else work with these hot?


If the cable tray fails structurally while the temporary supports are being installed, the results could be a disaster including risk of severe injury or even electrocution.

The incinerator does not fall under the OSHA criteria for a continuous industrial process.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25559

IMO is that repairing it hot is not only a bad idea, it is a violation of OSHA's _Selection and use of work practices_ standard, 29 CFR 1910.333, as it relates to "continuous industrial processes" and the infeasibility of de-energizing equipment under certain circumstances.

The definition is not what it may seem to be at first. The criteria is that shutting down the equipment would have to create a hazard or increase an existing hazard for hot work to be permitted. And then only if the work is deemed safe to perform, the procedures clearly spelled out, and signed off by all responsible parties concerned. Loss of production, profits, or inconvenience does not constitute justification under this statute.


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