iceworm
Curmudgeon still using printed IEEE Color Books
- Location
- North of the 65 parallel
- Occupation
- EE (Field - as little design as possible)
I'm caught up with an issue of is it okay to stand on a cable tray to perform a maintenance task - like say change a light bulb above the tray.
My first response: "Uh, well, No. There is a warning label on the tray that says, 'Do not use tray for personnel support'. "
Response: "For the past 30 years we have been putting a piece of plywood over that section of tray, climbing up on the plywood, and changing the light bulb. The tray has been holding us fine."
So, I estimate the weight of the cables in the tray, measure the distance between the supports, and do a structural calc. The tray will easily support an additional 250 lb point load with a 2.5 safety factor. Hummm - now what
Guiding regulation is (2008) 110.3.B.
I look up "Listed", "Labeled" (art 100), cable tray in the UL White book (CYNW)
Cable tray is "Classified". I did not find a standard. It is listed: http://database.ul.com/cgi-bin/XYV/cgifind.new/LISEXT/1FRAME/srchres.html?begin=10&collection=/data3/verity_collections/lisext&vdkhome=/usr/app/verity_sw_rev24/common&query=CYNW%3CIN%3ECCN+and+not+GUIDEINFO&SORT_BY=textlines:asc,ccnshorttitle:asc
Here is the guide info: http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?&name=CYNW.GuideInfo&ccnshorttitle=Cable+Trays&objid=1074080954&cfgid=1073741824&version=versionless&parent_id=1073985303&sequence=1
The only thing discussed is the bonding between sections:
For a comparison, if one were to look at the White book entry right above the one for cable tray, CYMX, Cable sealing fittings for use in hazardous locations, there are several references to look at the manufacturer's instructions included with the fitting. And there is a Ul standard referenced. In the CYNW entry, similar references to "manufacturer's instructions" are conspicuously absent. And there is no UL standard referenced either.
I did a Forum search on "listing + instructions:
http://forums.mikeholt.com/showthread.php?t=140731&highlight=listing+instructions
Don's comment in post 8 seems to fit.
So finally, the questions:
What exactly are the "instructions included with the listing or labeling"
What exactly does "classified" mean?
Yesterday I would have thought they were the instructions that came in the box with the equipment. Today - maybe I don't know.
Where am I going with this?
In general, I don't like the idea of standing on a plywood cover on a cable tray - me thinking that makes it neither unsafe or illegal.
In this particular case the tray contains low voltage instrument cables. The area is tight to where building a scaffold is a multiple day affair. I can do a structural calc showing an adequate safety factor.
So the Osha/AHJ rep comes in and sees the crew standing on a plywood cover over the tray, right above where a bright red label says, "WARNING - DO NOT USE AS PERSONNEL SUPPORT". How do I explain this is okay - with out turning red-in-the-face, mumbling, and eyes downcast.
I don't know if the response would be:
I'm interested in references, thoughts, opinions
the worm (continuing the search for wisdom and knowledge)
My first response: "Uh, well, No. There is a warning label on the tray that says, 'Do not use tray for personnel support'. "
Response: "For the past 30 years we have been putting a piece of plywood over that section of tray, climbing up on the plywood, and changing the light bulb. The tray has been holding us fine."
So, I estimate the weight of the cables in the tray, measure the distance between the supports, and do a structural calc. The tray will easily support an additional 250 lb point load with a 2.5 safety factor. Hummm - now what
Guiding regulation is (2008) 110.3.B.
Listed or labeled equipment shall be installed and used in accordance with any instructions including in the listing or labeling"
I look up "Listed", "Labeled" (art 100), cable tray in the UL White book (CYNW)
Cable tray is "Classified". I did not find a standard. It is listed: http://database.ul.com/cgi-bin/XYV/cgifind.new/LISEXT/1FRAME/srchres.html?begin=10&collection=/data3/verity_collections/lisext&vdkhome=/usr/app/verity_sw_rev24/common&query=CYNW%3CIN%3ECCN+and+not+GUIDEINFO&SORT_BY=textlines:asc,ccnshorttitle:asc
Here is the guide info: http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?&name=CYNW.GuideInfo&ccnshorttitle=Cable+Trays&objid=1074080954&cfgid=1073741824&version=versionless&parent_id=1073985303&sequence=1
The only thing discussed is the bonding between sections:
"Cable-tray assemblies have been investigated for bonding between sections using the minimum hardware provided by the manufacturer ..."
For a comparison, if one were to look at the White book entry right above the one for cable tray, CYMX, Cable sealing fittings for use in hazardous locations, there are several references to look at the manufacturer's instructions included with the fitting. And there is a Ul standard referenced. In the CYNW entry, similar references to "manufacturer's instructions" are conspicuously absent. And there is no UL standard referenced either.
I did a Forum search on "listing + instructions:
http://forums.mikeholt.com/showthread.php?t=140731&highlight=listing+instructions
Don's comment in post 8 seems to fit.
So finally, the questions:
What exactly are the "instructions included with the listing or labeling"
What exactly does "classified" mean?
Yesterday I would have thought they were the instructions that came in the box with the equipment. Today - maybe I don't know.
Where am I going with this?
In general, I don't like the idea of standing on a plywood cover on a cable tray - me thinking that makes it neither unsafe or illegal.
In this particular case the tray contains low voltage instrument cables. The area is tight to where building a scaffold is a multiple day affair. I can do a structural calc showing an adequate safety factor.
So the Osha/AHJ rep comes in and sees the crew standing on a plywood cover over the tray, right above where a bright red label says, "WARNING - DO NOT USE AS PERSONNEL SUPPORT". How do I explain this is okay - with out turning red-in-the-face, mumbling, and eyes downcast.
"Ahhh ... Here is the load calc showing it will hold the load. There is nothing in the White book saying we must heed the mfg instructions other than about bonding. The plywood is secured so it won't slip".:ashamed1:
I don't know if the response would be:
"*&^%$^#@$$ Morons" as she turns away.:happysad:
or"Here's your citation"
I'm interested in references, thoughts, opinions
the worm (continuing the search for wisdom and knowledge)