i have had several questions given to me in ref. to the use of gfci to supply a 120v 20ampere circuit receptacle and the way i saw the code the protection had to be at the origin of the circuit not at the end as some have told me , where they install a gf receptacle in the outlet box,

please explain for us, thanks roger

According to 645.(D)(2) Branch-circuit supply conductors installed in rigid metal conduit, PVC conduit, intermediate metal conduit, electrical metallic tubing, electrical nonmetallic tubing, metal wireway, nonmetallic wireway, surface metal raceway with metal cover, surface nonmetallic raceway, flexible metal conduit, liquidtight flexible metal conduit, liquidtight flexible nonmetallic conduit, MI cable, MC cable, or AC cable are permitted in the raised floor space.

And the branch-circuit wiring methods must be securely fastened in place in accordance with 300.11.

However, power, communications, connecting, and interconnecting cables part of listed information technology equipment aren’t required to be secured in place [645.5(E).

Here is an informative presentation of difficulty implimenting of Article 645. http://www.bicsi.org/Content/Files/PDF/link2006/Stanitis.pdf

I have had this argument with insectors for years. It is good to have it brought out in the open like this. I also liked the option of watching Mike tell us about it via the internet. Thanks Mike.

should have mentioned that it must be installed 1 1/4" back on the stud

Other than "Caddy-clip Bat wings" for #9 ceiling support wires, what else is a listed support for the same application ?

Mike, I don't have the Building Code Books readily availible where I am currently located. I may be completly wrong in my posting, if so I apologize.

I have had a little time to look at NEC Article 645. Here are some references located there as to room occupancy.

645.4(4) The room is occupied only by those personnel needed for maintenace and functional operation of the installed information technology equipment. 645.4(5) The room is seperated from other occupancies by fire-resistant-rated walls, floors, and ceilings with protected openings. 645.4 FPN For futher information on room contruction requirements, see NFPA 75-2003 Chapter 5.

i use a lot of mc cable here at work. the cable is very easy to work with and gives me protection and a 20 amp feed for power

On a semi related issue, could you address cable support for a manufacture wiring system when applied beneath a 16" to 24" raised floor that occurs throughout an entire office building (not a server farm, co-location site, or data center). Code indicates that the cable shall be supported in same manner as required for product used in manufacture wiring system, which is mainly MC cable. MC cable can be routed through studs at 16" spacing or greater and be considered supported. Beneath a raised floor the manufacture wiring system is laying on a concrete deck. Some locations require the system to be strapped to the concrete at 6 foot intervals. What is your understanding of the code here? For Informational Technology Rooms Art. 645.5(E), power branch circuiting is not required to be secured under the raised floor. How and why is an office application different? To secure cables of a manufacture wiring system defeats the flexibility of the system.

Since 320.30D allows: "fished through concealed spaces in finished buildings or structures, where support is impracticable;" providing a cut-in box, with AC fished to accessible ceiling is code compliant, right? Any additional requirements for this technique? -Jamie Fox