From the 2011 NEC
"300.11 Securing and Supporting.
(A) Secured in Place. Raceways, cable assemblies, boxes,
cabinets, and fittings shall be securely fastened in place.
Support wires that do not provide secure support shall not
be permitted as the sole support. Support wires and associated fittings that provide secure support and that are installed in addition to the ceiling grid support wires shall be permitted as the sole support. Where independent support wires are used, they shall be secured at both ends. Cables and raceways shall not be supported by ceiling grids.
Note that the 'extra' wire that is installed for electrical use, shall be supported at 'both ends'! That means that it has to be connected to the grid,
Caddy makes (made) a yellow item that clipped onto the grid to 'secure' the electric support wire.
As to the color of the wire, I do not know of a 'code' reference; I believe it is a local thing. Guys here use red, green, yellow paint.
The 'yellow' clips were touted as a means for an AHJ to determine IF the wire used for electrical support is for that purpose only.
FWIW, I have not seen anyone install conduit above a drop ceiling supported by wire. Not saying it is not done, but I have not encountered it.
Last edited by HotLine1; 02/19/14 11:33 PM.