ScTP Cabling project , unsure on grounding options 3

[rpearson]

Ive been hired to project manage a cabling project which will incorporate scTP Cat5e (w\shielded hardware) horizontal cabling in a high bay shop\warehouse environment. I currently do not have a current NEC or EIA\TIA codes\standards available to me for reference.

My hangup is properly grounding this cabling system , and making sure its done right. Would appreciate any feedback or links to information on this . THX

 

[Sleepsalot]

Not To be ugly how did you get the project managers job with out knowing what the specs are.

Wayne

Life is a big Roleplaying adventure.

Wayne

 

[franklin97355]

Properly ground the racks and the rest should ground through the equipent. (panels ground through the rack, cables ground through the panel, etc.)

 

[rpearson]

Well sleepsalot , judging by your post , explaining my position and why this and why that , may get a little complicated for you....Just a little cable guy humor is all.

 

[Sleepsalot]

Hi rpearson,

As I said it was not meant to offend you. But I'm sure a search on google or dogpile would give you the current NEC or EIA\TIA codes\standards. This has been the best source of info that I know. The MSI manager at my school even uses the search engines and he has had his job for the past 13 years. And has been an instructor for 20 years.

Again No offense intended
Wayne

Life is a big Roleplaying adventure.

Wayne

 

[DenneyM]

did rpearsons' question get answered? I could probably help if the need is still there. Let me know

 

[Kaycek]

I don't think it did...

rpearson, one thing I do know, if you are running cable through walls, the cable needs to have a plenum cover. Also, why do you want to use STP instead of utp Cat 5e

Kaycek
~~~~~~~~~~~~~~~~
Don't give up and Don't give in

 

[daronwilson]

if you are running cable through walls, the cable needs to have a plenum cover.

I'm not sure where you got this info, you might want to confirm it. Plenum rated cabling is required when the cable is in air handling spaces. Inside the wall is generally not considered an air handling spaces.

Good Luck

Daron J. Wilson, RCDD

 

[Kaycek]

I got that info from the Net+ book by Tamara Dean. The book is "The Network Guide to Networks", and since I didn't do too good a job from memory, let me quote her here, now.

"...If you run cable in the plenum, the area above the ceiling tile or below th subflooring, make sure the cable sheath is PLENUM-RATED [the plenum was my mistake] and consult with local electric installation codes to be certain you are installing it correctly. A plenum-rated cable is more fire-resistant than other cables and its sheath will not release noxious fumes if it does start to burn..."

What she doesn't say is that the plastics, not only of cable, but of all the plastic storage ware, and the insulation sheath give off cyanide when they burn.

I hope that will help, and clarify things... I've been saying plenum for 3 years and no one corrected me...I always thought that plenum was the name of the sheathing. I do apologize.

Kaycek
~~~~~~~~~~~~~~~~
Don't give up and Don't give in

 

[bkrike]

Kaycek-
You have two options for the sheath when dealing with inside wire: Plenum or PVC. Plenum was designed to be used in certain HVAC systems where the entire ceiling space above grid is part of the air handling system. If you stuck you head above the grid it would be the same temperature as below. You would still see duct work since air handling systems have both a supply and a return. I believe that the ceiling space is typically used as the return, and the duct work would be the supply pushing new air into the suite (but it may be visa-versa...I am not an HVAC guy and don’t know for sure.)

You are correct in the statement that it as designed because PVC jackets will give off toxins in a fire. Here lies the fact that has always caused me to think of Plenum cable as such a waste of money. I mean if there is actually a fire, does it really matter that some V-D cabling might give off some bad fumes? The fire itself, along with the CO and smoke produced by it are just as dangerous, besides the fact that you are going to get the heck out of the building before said fumes ever touch your nostrils. If you don’t make it out, there are a 100 other products of combustion to kill you just the same.

Some jurisdictions require Plenum for all commercial construction. Plenum cable typically costs 2.5 - 3 times as much as PVC.

 

[daronwilson]

"...If you run cable in the plenum, the area above the ceiling tile or below th subflooring, make sure the cable sheath is PLENUM-RATED [the plenum was my mistake] and consult with local electric installation codes to be certain you are installing it correctly. A plenum-rated cable is more fire-resistant than other cables and its sheath will not release noxious fumes if it does start to burn..."


Well thanks for quoting, i wasn't picking on your plenum or plenum rated terminology, just that the statement is incorrect. And man I just can't complain about your effort, you bought a book and read it! Unfortunately, the author did not do a very good job of explaining the details. I'm not familiar with the book or the author, always a good idea to find out if the author has actually done this type of work and what his/her background is.

The National Electrical Code 2002 Article 100 defines Plenum thusly: "A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system." The NEC Article 800.53(A) says (A) "Plenum. Cables installed in ducts, plenums, and other spaces used for environmental air shall be type CMP."

Now, in residential construction for example, often they select a stud bay, the void between two studs in wall to be a vertical plenum to get return air from one floor to the next. They usually paint that stud bay and we can't run wire through there unless it is plenum rated.

In commercial type construction, there are some common misconceptions. If there is a drop ceiling in place, that is NOT necessarily an idication that the space above it is a plenum space. IF you look above the tile and there are heading ducts AND return air ducts, then the environmental air is contained in that duct work, and that area above the tile is not a plenum space.

The same goes for raised floors, if they are ducting the air in and out, it isn't a plenum space.

One example of these types of space that we run into are some schools where there are 'tunnels' under the school hallways that contain piping. At many of them, there is a large air handler that pressurizes the entire tunnel area, and they have ducts and vents going to the classrooms. It's similar to a wind tunnel when the heater is running, but THAT area is all plenum space, anthing in that space needs to be plenum rated.

Hopefully that makes sense. Simply, if they are moving environmental air (HVAC breathing air, forced or return) through the space in question, you need plenum rated material.

This book looks like it covers the Net+ material from someone who has probably never been in the field and pulled wire. I would recommend if you are looking for cabling books, look for those by people who do cabling. This book appears to be a 'how to pass the NET+ exam' type book. Not the greatest reviews on Amazon. Sorry, it's frustrating when there is misinformation in something this widespread, but it looks like she missed the boat in a lot of areas. If i wasn't so busy, i'd get the book and challenge her on her mistakes

good luck!


Daron J. Wilson, RCDD

 

[daronwilson]

Actually there are a bunch of these books used for $2.19, go figure, maybe I will invest in it and see how off it is.

Another issue on the quoted statement, I don't believe that by default a plenum rated cable is necessarily more fire resistant than PVC; and it will release noxious fumes, but at a much lower level than PVC wire.

Daron J. Wilson, RCDD

 

[Kaycek]

I didn't take any offense I just was surprised that it was "plenum-rated" instead of plenum.

Y'all are right it is a 'how to pass the NET+ exam' book. I'm on the forum to learn the real world way vs the dry boring non-meaningful, sleep-inducing ways that are in her books.

According to the back of the book, "she has 12+ years or networking expertise, during which she has been a network engineer and a LAN administer, [just quoting the poorly written back of the book]and most recently the manager of network and data center options at a major Internet services firm in the Midwest"

All of that tells me she is a fancy pencil pusher who managed to get a way to write a book...

bkrike,

I agree with you, 100%, unfortunately, I live in one of those jurisdictions that code says plenum-rated cable is used in all construction.

You are also right about the duct work pushing heated air into the room, however warm air rises, and so the "cold-air returns" are normally in the floor.

They are also the nice little grids that you will see in a sidewalk (the little ones, not the big ones) that we women walk around when we're wearing skirts.


Hey, if y'all really want one of those books, give me a week, until I take and pass the test, then I have both a second and a third edition that I will happily give you. I've learned more about running cable here, then through the book... now if I can just get the kindsof the cable and the protocols down I'm made in the shade.

thank you everyone for your patience with me.

Kaycek
~~~~~~~~~~~~~~~~
Don't give up and Don't give in

 

[daronwilson]

Very good points.

Often on slab construction there is no way for the returns to be lower, so they just hang it all in the overhead.

Drop me an email if you don't mind and i'll see if can arrange a book sale for you. Should be one i can get cheap enough to put in the library.

daron (at) wilson (dot) org

thanks,

Daron J. Wilson, RCDD

 

[ISDNman]

Not sure if everyone here gets the intent though. Since the Plenum spaces are air returns, the rationale is that toxic fumes in the plenum space will immeidately be spread far and wide within a building - even to other floors.

Also, since in a plenum there is moving air, the cabling there would burn at a faster rate than simply in the open.

Now of course the air handling system will eventually suck in the smoke and blow it into other spaces, but these standards are concerned with maximizing the time to evacuate, particularly for those on other floors who may doubt there is a fire.

I don't know the HVAC implications of the NFP Codes. It would seem logical to have temperature or CO sensores in every return air plenum to SHUT OFF the HVAC in the case of fire but I have no idea if this is recommended or required since it it soutside my area of expertise.

My pet peeve is that IMHO frequent mandatory "fire drills" serve to reduce the odds of evacuation by training people to ignore fire alarms.

 

[franklin97355]

At our school district if there is a fire drill you will exit the building just like everyone else. No exceptions. If you don't you get to talk to the boss.

 

[daronwilson]

It's a bit off the topic, but the requiring of duct detection (i.e. smoke detectors in the air ducts) and fire dampers (closing off the air flow) is dependant on both occupancy rating and the size of the air handler unit. Smaller air handler units, and physical compartentization of the structure can eliminate the requirement for those devices.

Where they are required, the duct detectors generally close the fire dampers immediately to stop the flow of air. Depending on the system, the air handlers may be shut off as well with that signal, or often they sense the over pressure in the duct work with the dampers close and shut down that way. Many ways to meet this requirement depending on how you design the fire system.

As with almost all fire codes, they are knee jerk reactions to large loss of life and/or property. Not that it is wrong, but generally, they go a bit overboard to prevent that large loss from occuring again.

good luck!

Daron J. Wilson, RCDD

 

[Servamatic]

Just for the record....
Plenum rating has nothing to do with toxicity, it has everything to do with flame spread rate and visibility.
Plenum rated cables give off a whiter smoke to aid visibility so you may exit the area.
plenum rated also burns much slower than non-plenum. CMP type cable will extinguish itself quite rapidly if you remove the flame source, whereas CMR and lower type cables will continue to burn.
All cables are toxic if you breathe enough of the fumes when burned, regardless of the composition. Since CMP burns slower it stands to reason it will put out less smoke, but I sure wouldn't hang around to breath any of it.



Richard S. Anderson, RCDD

http://www.servamatic.net

 

[bkrike]

Servamatic-
What is your source / reference for the statements above?

 

[rpearson]

Unsure why this even became a PLENUM subject. In either case , Ive solved any and all of my dillema. Thanks all.