Clearance Above Suspended Ceilings - Ref?

[smalltime]

Okay, I know that independent support needs to be provided/installed for plenum rated cabling installed in the plenum. Can't use the ceiling support wires, raceways, etc.
I've heard that the supported cables must have at least 3 in of clearance above the suspended ceiling and that the support must be every 4 or 5 feet but I can't find this in 800 or 300.11.
I looked at the ANSI/NECA/BICSI 568 dated 2001 and can't find a reference there either.
Is this Code, somebody's standard, tribal knowledge or what?

 

[mcclary's electrical]

Okay, I know that independent support needs to be provided/installed for plenum rated cabling installed in the plenum. Can't use the ceiling support wires, raceways, etc.
I've heard that the supported cables must have at least 3 in of clearance above the suspended ceiling and that the support must be every 4 or 5 feet but I can't find this in 800 or 300.11.
I looked at the ANSI/NECA/BICSI 568 dated 2001 and can't find a reference there either.
Is this Code, somebody's standard, tribal knowledge or what?

When you support cable with ceiling wire, you still support it at the intervals for that certain wire. AC cable support,,,,,and MC cable support,,,,would be 2' different.

As for the 3",,,,you cannot interfer with removing the ceiling tile, so 3" would probably be the minimum to accomplish that

 

[hbiss]

I've heard that the supported cables must have at least 3 in of clearance above the suspended ceiling and that the support must be every 4 or 5 feet but I can't find this in 800 or 300.11.

Assuming LV wiring, that's because there is nothing that specifies that. Workmanship maybe, but that's about it. Cables cannot rest on the grid or tile but as long as it's supported above them it's OK. Consider all the other stuff that restricts the removal of tiles. When was the last time you saw a ceiling change height below a beam so that you can push the tiles up?

-Hal

 

[smalltime]

Thanks for the replies, and yes, this is about LV wiring. And while I agree that 3 in is probably a good minimum, it still doesn't answer my question...

3 in and every 4 1/2 ft or whatever. Says who? Since I don't don't believe it's Code (or I've just missed it), who says it's 3 in? Why not 4 or 5 or 6 in?

I just have somebody that stated 3 in and I would like to know the basis for their statement. Is it a NECA Workmanship standard? BICSI standard? TIA/EIA? Krispy Kreme?

Just trying to find a published industry source other than, "Because he said so."

 

[Rockyd]

Okay, I know that independent support needs to be provided/installed for plenum rated cabling installed in the plenum. Can't use the ceiling support wires, raceways, etc.
I've heard that the supported cables must have at least 3 in of clearance above the suspended ceiling and that the support must be every 4 or 5 feet but I can't find this in 800 or 300.11.
I looked at the ANSI/NECA/BICSI 568 dated 2001 and can't find a reference there either.
Is this Code, somebody's standard, tribal knowledge or what?

Text revised to clarify that the accessible portion of abandoned coaxial cables must be removed.
New FPN alerts the Code user to a comprehensive standard that identifies what "installed in a neat and workmanlike manner" means. And section revised to that CATV cables must be secured in place and that the ceiling support wires or ceiling grid must not be used for this purpose.

From this link...




New FPN alerts the Code user to a comprehensive standard that identifies what "installed in a neat and workmanlike manner" means.


And revised text specifies that optical fiber raceways and cables must be secured in place and that ceiling support wires or the ceiling grid are not permitted for this purpose in accordance with 300.11

New FPN alerts the Code user that limiting the length of the grounding conductor should reduce voltages that may develop between the building's power and communications systems during a lightning event.
New subsections added to recognize the use of raceways designed for coaxial cables.

Yuppers, another link

Good possibility that National Electrical Industry Standards (NEIS) may have some verbiage committed to paper too(strictly conjecture on my behalf).

 

[smalltime]

I think I have it now.

800.24 Mechanical Execution of Work - Commentary
"Although this requirement does not contain specific supporting and securing intervals, it does reference 300.11 as a general rule...."

800.24 FPN (FPNs not being enforceable as part of the Code) refers to industry accepted practices as outlined in:
ANSI/NECA/BICSI 568-2006 (This is actually an ANSI standard)
TIA/EIA -568-1.1-2004
ANSI/TIA-569-B-2004 (Another ANSI Standard)


300.11 (A)
"Cables and raceways shall not be supported by ceiling grids."

So don't lay it across the grid.


And 800.21
"Access to electrical equipment shall not be denied by an accumulation of communications wires and cables that prevents removal of panels, including suspended ceiling panels."

"Accumulation" not being clearly defined and an argument for another thread.


So the bottom line is while there is no Code for clearance, there may be a Standard. So unless there is a standard that says 3 in, it's Tribal Knowledge and Verbal History.

FWIW, I ordered the ANSI/NECA/BICSI 568-2006. $30 from ANSI in pdf only. NECA was $40 hardcopy with free shipping. BICSI was $28 hardcopy but with $20 shipping.
NECA wins.

I do have Mike's 2008 NEC books. Great stuff. Just trying to make sure I wasn't missing something.

Thanks!

 

[Rockyd]

I do have Mike's 2008 NEC books. Great stuff. Just trying to make sure I wasn't missing something.

Well written, and easy "to get it", even for me

A lot of bang, for the buck!